a eet a ~ >" > m4 ‘ ty tet tee “yet t : ; : ' : ‘ ' A soehed po okt Ay Uae oe Bu fe BRE BN eh oe on H is PRPS E SRE | +449 ‘ o> ig ; FetaeRAIER 8, bef CAD bott balk By ° a teed i bas THE UNIVERSITY OF ILLINOIS LIBRARY SN26 » M42 Me Return this book on or before the Latest Date stamped below. A charge is made on all overdue books. University of Illinois Library I eyt F Por M32—30715 i ee " Stee > eee tee a “ - « coe r- : lat o . s 2 Bet ar Gs d MEASUREMENTS OF MECHANICAL ABILITY BY Joon L. STENQuIsT, Pu.D. TEACHERS COLLEGE, COLUMBIA UNIVERSITY CONTRIBUTIONS TO EDUCATION, NO. I30 PUBLISHED BY Teachers College, Columbia Aniversity NEW YORK CITY 1923 Copyright, 1923 | : é By . 4 JOHN L. STENQUIST G Was hard law etter te es F180 Cr AT, WG Jt +2We. Pbcee+ ACKNOWLEDGMENTS To Professor E. L. Thorndike, who is at once the inspiration and guiding genius of all who are so fortunate as to be associated with him, is chiefly due whatever merit this study may have, and grateful acknowledgment is here made of my great indebtedness to him. Very great credit is also due Professor H. A. Ruger for his unfailing personal interest and constant helpful counsel. Professor W. A. McCall has given much help in the statistical treatment of the data. To the principal, assistant principals, and shop teachers of Public School No. 64, Manhattan, credit is also due for codperation in the giving of many tests. Ajai ue Digitized by the Internet Archive in 2022 with funding from University of Illinois Uroana-Champaign Alternates https://archive.org/details/measurementsofme0Osten IV. VII. VIII. CONTENTS PART | A DESCRIPTION OF THE TESTS * . INTRODUCTORY . TESTS OF GENERAL MECHANICAL ABILITY— Definition of Terms; Nature of Tests Used : ae Pome OF ASSEMBLING T&sTS—ORIGINAL SERIES [ . Models Included in Original Series I 2. Method of Giving and Sagringy 3. Results with Original Series I MEASURES OF 697 CHILDREN IN > eee eee ABILITY Scores of Normal Children. en oe . RESULTS AND Conct.ustons FROM. THE FIRST EXPERIMENT VI. Sune ae OR ASSEMBLING Test—Orictnat SERIES II . Models included in Sefies II 5 2. Method of Scoring ¥ 3. Results with ae Serie el 4. Conclusions ke Re RECOGNITION OF Mecuanican, DEVICES OR MECHANICAL INFORMATION TEST— * # 1. General Nature. #.2.% 2. List of Mechanical Devites i in NRecneniion Test 7 3. Results with Recognition Test 4. Correlations 5. Relative Gaminenness? A Rach Device 6. Conclusions SINGLE MODEL SERIES . I. Single Series I . 2. Models Included in Shiela ae ar Preliminary Trials with the Single Model Ste 3. Single Series II ENS 4. Models Included in Single Sho IL Preliminary Trial of Single Series II with Sidoie Series I 5. Correlation of Each of 20 Models with Criterion . 31 33 33 33 * The Mechanical Assembling Tests herein described may be obtained from Chas. Stoelting Co., 3037 Carroll Ave., Chicago. The Picture Tests of Mechanical Aptitude are published by the World Book Co., Yonkers, N. Y. v Vil is XIII. XIV. eV XVI. XVII. Contents Vigan : . . A New Method of Sealine: The McCall Method . Advantages of the Method hea 2. Relative Difficulty of Each Model . 3. Old Order and Final Order of Models 4. Difficulties in Obtaining Certain Models : 5. T-Scale Values for Each Raw Score of Series I and Setes lie ree EM §, Tk ee a) The Binal peoane a 2 b) The Adult Norms c) Grade Norms d) Girls’ Records . FORM OF DISTRIBUTION OF MECHANICAL ABILITY . THE PARTIAL SCORE FACTOR The Short Form Test . SERIES III, ASSEMBLING TEST, FOR LOWER GRADES . Models of Series III for Grades 3, 4, 5 and 6 SUPPLEMENTARY MODELS RELIABILITY . CORRELATIONS 1. With General Latellivences ; 2. With Other Criteria of General Mechanical Ability ; SUMMARY OF ASSEMBLING TESTS . MEASURING MECHANICAL APTITUDE BY MEANS OF ILLUSTRA- TIONS; PICTURE TESTS OF MECHANICAL APTITUDE 1. Aim and Purpose . . Description a) Selection of Siibece Matter b) Scoring; An Improved Method 3. Picture Tests 1 and 2. Jipree a) Scale Difficulty Values . ; b) T-Scale Values for Each Raw Store : 4. Reliability of Picture Tests 5. Correlations with Assembling Tests bad with Ehon Regis 6. Summary of Picture Tests of Mechanical Aptitude NS PAA I LeeeL THE NEED FOR A BROADER DEFINITION OF GENERAL INTELLIGENCE XVIII. ILLUstrRious SCHOOL FAILURES XIX. THe LARGE PERCENTAGE oF ‘‘Low INTELLIGENCE” XX. WHAT IS GENERAL INTELLIGENCE? 76 78 79 XXI. ¥Y XXII. ¢ XXIII. XXIV. XXV. XXVI. XXVII. Contents OTHER KINDS OF INTELLIGENCE stapes INTELLIGENCE AND MECHANICAL ABILITY . The Intelligence Tests . /2. The Mechanical Tests . ; ‘ a) Analysis of Total Peecnhition é 4b) The Trustworthiness of the Meagure mente /c) The Validity of the Measurements . THE RELATIVE IMPORTANCE OF THESE Two KINDS OF ABILITY FICTITIOUS STIGMAS . SUMMARY OF ParT II APPENDIX ASSEMBLING TESTS—DIRECTIONS FOR THEIR USE . MECHANICAL APTITUDE TESTS—DIRECTIONS FOR THEIR USE Vii PAGE 81 82 82 82 86 86 87 89 90 gI 92 99 XIII. XIV. XV. XVI. viii TABLES . Frequencies of Scores Attained by 432 Children in the Original Series I Mechanical Test . . Illustrative Results with Original Series I . . Distribution of Scores for College Students for Each Model— Original Series IT . Time Per Model—Original Series II . Distribution of Scores in Case of 100 Eighth Grade Pupils . . Coefficients of Correlation Between Recognition and Con- struction Tests and School Subject . Percentage of Right Scores for Each Model with S. D. Equivalents . . 5S. D. Distances of a Given Per Cent Above Zero . T-Scale Scores for Each Number eae Series I, with ey Distributions . T-Scale Scores for Each Number esi Series II, with Age Distributions . Correlations Between Scores When Counting Only Models Perfectly Solved, and When Counting Partial Scores . General Scale Values in Terms of S. D. for Grades 6, 7 and 8 . Average Difficulty of Each Element of Picture Test I Average Difficulty of Each Element of Picture Test II . T-Scale Scores for Each Number Right for Test I with Age Distributions age UC mo, Get ih. Ue ee eae T-Scale Scores for Each Number Right for Test II with Age Distributions EUS LT REREAD OR CMs! 2 PAGE 9 13 19 19 20 24 38 44 45 46 53 55 67 68 79 71 FIGURES Cut showing Original SeriesI . . . . . . +. . . facing Gut showing Original Serieslie.. 4. a) ee ee Cut: showing’ Recognition Test. 6. ks Gk eens) . Cut showing Single Series I—Final Form. . . . ._ . facing . Cut showing Single Series [I—Final Form... . . facing Scale Difficulty Distribution of Models for Series I and Series II Form of Distribution, Series I, for Grades 6, 7 and 8 Form of Distribution, Series II, for Grades 6, 7 and 8 Form of Distribution, Series I, for Grades 7 and 8, Individually Form of Distribution, Series II, for Grades 7 and 8, Individually . Form of Distribution, Series I, Men in Army . Cut showing Series III for Grades 3,4,5 and6 . . . _ . facing Form of Distribution, Picture Test I, Grades 6, 7, 8, Combined Form of Distribution, Picture Test I, Grades 6, 7, 8, Individually Form of Distribution, Picture Test II, Grades 6, 7,8, Combined . . Form of Distribution, Picture Test II, Grades 6, 7, 8, Individually Correlation of Four Intelligence Tests with Four Mechanical Tests Correlation of Four Intelligence Tests with One Assembling Test Correlation of Four Intelligence Tests with Picture Test I ! | . | r ; } a tv ON ae wil sie vale ie av Vieoure de " 76! " : f 7 iia | et. Fe y) ig iy Jee AR! ey } Ne arpa ae OP Sa Ye # ae . LK da? aa the, in Mi AY ie y eS Pe , ‘ : ’ a v . . wa ' t ‘bh eee a: a Ra MS |S Ani SAE Ma ag nays ay 4) ‘ 1 ’ Coa) : hh y ‘ Ne y ' \ , id re! 1 Ps f A at " is i J orw : , ¥ in, ‘ Feat “a ¥) ij vy oy - NF. 94 { t vA ! CAN? ea Ritise j ‘ 7 * é ~ * 7% ; . > te " \ ; { Avy ‘ er Lara hs s eta Uailieg a y are ALN ‘ iv ee ’ : 4 + P ; , P a. socuh'® i f re 7; x ‘nia Yin eee Ae Tes AS? ‘. : os) omer e = i’ mers | : an ah | ! Hi » daa ERAN ae ae i . yi %A fi. : : us io ty, al . Bie byrae. | | i Bae That & Wr cule) Bo is eek a, iy ry Jr): ~ 4, > } , * ivi, iM i; at Sa a i ‘ pai ey Ms PAR Dict SECTION I INTRODUCTORY Tuis study presents descriptions, results, and conclusions resulting from experiments with mechanical tests carried on over a period of four or five years. The important feature is probably that it deals mainly with a new type of test material, namely, common mechanical articles of everyday life adapted for use as tests under standardized conditions. In addition to this, how- ever, are the results obtained in the use of picture tests dealing with similar mechanical objects, and mechanical situations, designed to test mechanical information, aptitude and ability. Little has thus far been done to make mental tests less aca- demic and verbal, despite the great interest that has sprung up in the general field. Yet it is well known that a large percentage of the population is ill adapted by nature and by training to excel in the verbal, pencil-and-paper tasks that are imposed by the aver- age mental test. By general agreement many of these are called measures of general intelligence, but it is certain that many abili- ties which could well be termed general are not measured by them. Any means of examining into the more or less unexplored abilities otherwise not reached is therefore important and this has been the guiding notion in the present research. e The tests described touch but a small portion of mechanical ~ activities that can be tested, but within their range they are believed to be significant. They deal specifically with the world of objects,—real things, as distinguished from words, and involve , both mechanical skill and abstract mental ability. While their nature is essentially mechanical they are in no sense trade tests, but should rather be considered tests of general mechanical in- telligence and manual aptitude. The picture tests do not, of course, test skill in the sense of providing objects for manipula-_ tion, but the ability to answer the problems correlates well with such skills. 2 7 Measurements of Mechanical Abtlity But the use of actual objects or mechanical devices as test material involves disadvantages as well as advantages,—disad- vantages in that physical objects are always more cumbersome to handle and to manage than printed forms. They are more expensive and require more time to use; they involve various minor difficulties, such as differences in supposedly identical ar- ticles due to minor details; such, for example, as the differing tension or stiffness of supposedly identical springs, etc. Models also wear out, are broken, bent or otherwise spoiled. The importance of measuring this ability, however, far out- weighs the obstacles met in the mere nature of the materials. It is well to keep in mind that modern life is permeated with ma- chines and mechanical devices on every hand, and that the ability to handle them is daily becoming more and more important to every one. We should also keep in mind that while but a small fraction of the population is engaged in the manufacture of this multitude of devices and machines, every individual in modern civilized life is concerned directly or indirectly with their uses. Ability in this direction is therefore of increasing importance. The past two or three decades have forced recognition of the importance of the general field of manual or industrial education and there is now scarcely a school that does not make some provision, no matter how inadequate, for manual work. An in- creasing number of elementary schools also now provide so-called prevocational courses for pupils above the 6th grade. The choice or rejection of mechanical courses by the average boy is apt to be on the flimsiest grounds, and it is here that standardized tests of general mechanical aptitude will be useful. Enormous differences are found among children of the same age or grade and it is believed that tests, such as those herein described, will prove useful in more intelligent, educational and vocational guidance of pupils. No claim is made that the whole problem of measuring me- chanical ability has been solved,—only that a small but specific contribution has been made. In the use of these tests, as in the use of all others, it is necessary to continually counsel the need of careful interpretation of results obtained, liberal use of common sense, and due consideration of all other factors involved. SEcTION II TESTS OF GENERAL MECHANICAL ABILITY DEFINITIONS OF TERMS; NATURE OF TESTS USED The term Mechanical Ability as here used means general aptitude in the management and manipulation of things me- chanical. It implies a general knowledge of mechanical princi- ples and usages, but does not imply any special trade skill. The tests described have been designed to measure the general me- chanical ability of young people of school age, who have learned no trade, but who may have much or little potential ability of this kind. Possibly it would be more appropriate to designate these tests by some_other name for they are mechanical only in a limited sense. The only mechanical skill involved is that of assembling, and this is, as every one knows, but a small part of the multitude of mechanical skills. -On the mental side they call for the ability to recognize parts of ordinary mechanical devices, for the ability to make judgments as to the reasons for the particular size, shape, weight and nature of the parts,—in short, for the mental ability to think through in some degree the same steps as those employed by the designer of each machine. Manually, they call for the dexterity required to put parts together to form the completed machine or device after it has been decided how they should go. Much of the performance of a typical child is, of course, mere trial and error manipulation, in which he hopes somehow to make the thing work. But the nature of the various models is such that only a very low score is possible for the individual who depends merely upon thoughtless manipulation of the parts. A generous amount of the best kind of thinking is thus required to make a high score. It involves accurate perception, reasoning and judg- ment, applied to each model, In so far, therefore, as these mental processes are of general importance in everyday life the ability demonstrated in assembling these models perfectly could well be called general intelligence. But since this term has been largely 3 4 Measurements of Mechanical Ability accepted as meaning a more abstract ability, it is not thought advisable to refer to these tests as general intelligence measures, but rather as tests of the general mechanical ability here de- scribed. Two general kinds of materials have been tried: 1. Assembling tests, in which actual disassembled objects are put together. 2. Picture tests, calling for judgments as to what parts belong together, and including questions on mechanics and machines. The idea of presenting a disassembled actual commercial article, such, for example, as a bicycle bell or mouse trap to be as- sembled, was first suggested by Professor E. L. Thorndike as a promising method of reaching certain capacities more or less un- touched by the more common verbal pencil-and-paper tests. In order to make them practicable as group tests in schools only such models as can be given to whole groups of pupils have been in- cluded. To meet this requirement it has been necessary that all models be relatively small, light and unbreakable, so that they can easily be carried about and used over and over, as well as that they be of such a nature that they can be readily disassembled or assembled. The final Single Series herein described probably represents the best types of models. They can be quickly and positively scored, and easily disassembled by boys after taking the test. While it would be desirable to include other operations besides assembling, this one activity was chosen as representative of many mechanical tasks and calls less for special trade skill than most mechanical operations. Thus, assembling is of a more general nature than, e.g., chiselling, chipping, filing, sawing, soldering, forging, etc., all of which require at least some trade training. The picture tests, however, cover a much wider range of ob- jects and operations, and include questions pertaining not only to simple and small objects but to large and complicated machines and processes. . "[ SOLS [PUISUQ ‘I ‘OT SEcTION III DESCRIPTION OF ASSEMBLING TESTS—ORIGINAL SERIES I The first test tried consisted of seven very common mechanical contrivances placed in a corrugated cardboard box, 16 by 16 by 2 inches, which could be placed on an ordinary school desk. This has been generally called the “‘Stenquist Construction Test,’’ Original Series if Fig. 1-shows-its-essential nature. I. MODELS INCLUDED IN SERIES I The objects placed in the box were: 2 Carriage bolts with nuts, 2 by 3 inches. 2 Pieces of safety chain containing Io links. 2 Small bicycle monkey wrenches. 2 Round wooden mouse traps. 2 Models made of three angle irons bolted together with Screws. 2 Small rim locks. 2 Bicycle bells. In the upper compartment was placed one complete set of the models, fully assembled. In the lower half was placed an exact duplicate set, completely disassembled. The task consists in assembling each model as rapidly and perfectly as possible. 2. METHOD OF GIVING AND SCORING Twenty-four children were arranged, one in a seat, in an ordinary classroom. After a record blank had been filled out, the following instructions were given: ‘‘Lay the paper which you have just filled out on top of your desk near one edge where you can get it easily later.’’ The twenty-four boxes containing the test materials were then distributed. Holding up one of the ' This test is described also in Stenquist, J. L., Thorndike, E. L., Trabue, M. R., ““The Intellectual Status of Children Who are Public Charges,’’ Archives of Psy- chology, No. 33, published by Department of Psychology, Columbia University. 5 6 Measurements of Mechanical Ability boxes before them, directions were given as follows: ‘‘Turn the box which you have on your desk so that the letter ‘F’ is toward you.! Do not look into the box till I say go.? ‘‘Each of these boxes is divided into two parts (indicating by gesture how the partition extended across the middle of the box). In the compartment or part farthest away from you there are seven mechanical models, i.e., seven mechanical things; one of them is a bolt with a nut on it; another is a small wrench; another a small chain; and there are four other things. ‘‘In the part nearest to you there are seven mechanical things just like the others except these are all taken apart. I want you to take all the parts in the compartment nearest you and make seven mechanical things exactly like the ones in the compartment farthest away from you as quickly as you can. As soon as you have finished them all, raise your hand; and we will write on your record sheet just how long it took you to do them all. ‘Begin with the one that looks the easiest. ‘“‘If you want to take apart any of the models to see how they are made you may do so, but you must put them together again. Screw all the nuts up tight; don’t leave them half on, but don’t use the wrench to tighten them with. Do you understand?” (Repeated if necessary.) “You will now get ready. Grasp the sides of the box so that you can take the cover off quickly when I tell youto. Are you all ready? Go!” The instructions being somewhat long, we found it necessary after the children began to work to give also the following in- structions. This was done after three minutes: “Do the ones that you think are the easiest first. Screw all nuts up tight with your fingers but do not use the wrench.” We found that two examiners could manage twenty-four sub- jects. Assoon asa hand was raised, the examiner noted the time from his stop-watch, walked over and entered it on the record sheet of that pupil. The pupil then replaced everything in the box and put his record sheet in the box ready to be graded. ‘At the end of 30 minutes all children were required to stop work. 1“*F’’ means front. '2 We found it necessary to be very vigilant in keeping the subjects from opening the boxes before the signal was given, as the pressure of curiosity became very great. A Description of the Tests 7 3. RESULTS The pupil’s achievement with each of the seven models was graded on a basis of 0 to 10, by an arbitrary schedule of partial score values. All perfect scores were given 10 points each. All seven models assembled perfectly in the full 30 minutes then gave a score of 10 X7,or 70. An arbitrary value of I was given every “‘gain-minute,’’ i.e., for every minute of the 30 that remained after the pupil had completed the test. For example, if the sub- ject completed the test in 16 minutes, I2 seconds, 14 points were added to his score. Fractions less than one-half minute were neglected. Fractions of more than one-half minute were counted as I. We found that after a little practice, and with skilled manage- ment of boy helpers, one examiner and four boy helpers can grade the twenty-four sets in about 40 minutes. We had then for each child a record like the following sample: Score Attained with Each ge Model Credit for | Total Br PPPS PP Te yy OP RT Ea FC Eee Time Score Pie Ge a lo ARC Sau Ca Waid ic ee tach atl Ee ED hd: 3 e) co a 9 e) 27 Path ay fe arc at FOr Ae (LO [LOW rel 10 3 fe) 63 ac ae ee een 10 | 10] 10 | 10 | 10 | Io | Io 8 78 SECTION IV MEASURES OF 697 CHILDREN IN MECHANICAL ABILITY Although the results obtained with this series, Original Series I, have, as already indicated (page 5), been reported elsewhere, the essential facts are here repeated for the sake of making this ac- count complete. SCORES OF NORMAL CHILDREN The test was first given to 432 unselected children in a New York City public school, and the scores tabulated. as shown-in Table I to yield age norms. From these norms true norms were estimated to be as follows: Age 6 7 8 9 10 II ue 13 14 15 to to to to to to to to to to | 8 9 Io II I2 13 14 15 16 Median Score..... SAMS AAS eS) (RAs A Shoes eS OLGn | O2e50100875 | 76.4 | 77.5 | 82.5 Estimated True SCOPES «cuss busbers 20 32 42 50 ef 63 69 75 19 82 The discrepancies between the obtained and estimated medians are due to the allowance made for especially bright six- and seven- year children. Having these norms the real work of the first experiment was begun, namely, to measure the ability of 265 children who were in institutions for dependent children. Four tests were given— Binet, Trabue Language, Thorndike Reading, and this mechanical test. By utilizing the median score for ages 6, 7, 8, etc., and inter- polating the scores for each intervening month, a table of age norms was built up.. It was then only necessary to read the table to determine the degree of over-ageness or under-ageness of any child subsequently measured. (Since the test in this original form has been discontinued the table is not here reproduced.) 8 | A Description of the Tests 9 TABLE I FREQUENCIES OF SCORES ATTAINED BY 432 ORDINARY CHILDREN AS TESTED IN A PuBLIC SCHOOL OF NEW YorRK CiTy—ARRANGED BY AGES 6=6.0upto7;7=7.0 upto &, etc. Age Score | |, es | | eS _ _ = _ pb = me NH WN IN) LS) tN a | on A s NW & & WD tN — O i) _ NS Ww WwW No om = ~~ = WD = =» me WD _ Ww Ww NO NON No oN -~ - wW _ _ ioe) ‘© ~ on 10 as eo * Sse 6.2 4) oom, @ 6 oP. e = 60s ae 3S é 8 bp a % Cla Pay Sito mC we yale |. Ce ie Ce ele ee » oe! 9,6 eee ee Rs ak ee 6 we le aye wie aie! weve Se. er Ge hk ape we CP ae ie o/ ce. tape Measurements of Mechanical Ability TABLE I—Cont#'d. Age a i | | | | | I I I 4 I I I 2 3 2 I 5 I 5 I 2 2 I 4 I I I 2 3 I I I 2 I I I I I I I I I 2 2 @ * I 2 2 2 I I I ee 2 r I I I I a. 6 I I I 2 3 2 I I I I I I 2 2 I I I I I I 3 I I I 2 2 I I 2 I 2 I 2 2 I 3 I I I I I I 2 I I I I I 3 B 2 I I 3 2 I I I 4 2 2 I 4 I 3 I I 2 I I 2 3 I 2 I I I I I 2 I I 3 2 I I I I I I I 2 I 3 I I I 3 I I I I 3 I I 3 s°e) 6m '% a A ps “re @ A Description of the Tests II TABLE I—Cont'd. Age I I I I 2 2 3 I I I I I I 6 2 I I I I I I I 2 2 I I 2 I I I 2 I 3 - I I I SECTION V RESULTS AND CONCLUSIONS FROM THE First EXPERIMENT As'a measuring device the experiment demonstrated the practicability of utilizing such materials as have been described. The interest displayed by the children was intense, and even those children who were almost complete failures at it were anx- ious to try. The test as a whole proved too easy (the more able finishing within 10 minutes with perfect scores) and hence was probably unreliable for individual deductions, but general averages are sufficiently reliable. The marked differences be- tween the type of ability measured by the mechanical test and the abstract intellect tests is significant. The records of 50 boys and 50 girls selected at random from the total results for all the dependent children are reproduced in Table II. The results show that the dependent children are as a group about 12 years behind in mechanical ability, but considerably more so in abstract intellectual ability. The 11- and 12-year- olds are about 2 years behind; the 13- and 14-year-olds about 23 years; and the 15-and 16-year-olds about 43% years behind. But the pupils behind in abstract ability are not always behind in mechanical ability. The percentage of unlike signed deviations is for the cases cited about .31, which is equivalent to a correlation of but about .5. Pupil 29, e.g., is 1.8 years behind in abstract ability but 3.3 years ahead in mechanical ability. Correlations with subsequent and more perfected mechanical tests show that the true correlation between intelligence tests and the mechanical tests is seldom over .4. Thus it is confirmed that a pupil may be inferior in academic school work and yet have marked ability in manual activities. But there is no evidence to support the popular notion of a law of compensation,—which assumes that low abstract intellect signi- fies high mechanical ability, or vice versa. Our correlations are low—but always positive—between the two abilities. .. If we know that a pupil is above average in abstract ability all we can predict with regard to his mechanical ability is that he is more likely to be I2 ; A Description of the Tests 13 TABLE II ILLUSTRATIVE RESULTS WITH ORIGINAL SERIES [| Boys Under-Ageness in ; Age Used in Com- | Three Tests of Ab- | Under-Ageness in puting Under- ___|stract Intellect Com- Mechanical Test. Identification Number Ageness Estimates | bined. (+ Equals | (+ Equals Over- Over-Ageness) Ageness) tA hte Mit cain. e abies eee snare’ ease TA —2.7 —8.7 TPA cic le dPibiens s+ o's a Wf AE ate Kee Tait — .I +2.1 a: ee ER 8 Ses len 10.0 —1.3 +4.5 hs SR ee arm oping Ai dd 13.8 —3.0 —3.0 = tes Sor eirtqcc merece 10.4 + .1 —1I.5 PIE Rae ow oie aera Ay 10.2 —I.I —2.9 ae ee ee aE ee Abe a P 9.8 + .4 +3.4 set & Me ce die ace ae etee hates 14.? — .8 ae NS ee Peg ae tis, SV Pe tea 9.8 —1.8 —3.1 fet oe Ee at i RR) S8 eee 12;2 20 +1.4 ny Eee eee Rte. = Ted — .8 ee eMac wae Me O:Slosdis as 14.0 —3.1 —2.2 SAM oe Te ee Se, eee e TAsa: —1.6 +1.1 SURiaAe WAGE ai ON oiehe ig tea a oe 3433) —I1.2 +2.3 a te eat, oe eet ar ee aia T2a0 —2.7 wate gc Ae Ce ES ay 13.0 + .2 sie ee 5 ey ee ee CRASS, 13.8 +1.8 —1.3 fe AR An ee, eee ie! 10-7 —1.6 —I1.4 AEE de Re, 2 oad ns Tait —2.7 —1I.0 So Re ee Ea we r27 —I.1I + .3 tr Oe OO ee ces 10.3 + v1 +1.3 eer renee te Oke ce ies Sea eA 13.6 — .3 +3.4 SNES Sd aunt essa) ake tion Siamiteere es 9.9 + .I +3.5 Cie) RONR nes, ara aes ah 4 eee Md, # — .9 — .4 np 20 RO on ER he Ca Ee 12.8 =2):9 WERE Sn ct! St ERR SA Peer 12*4 —2.4 ae POM Ee canes, Maciek e. 14.? —3.0 ae Bes Pos 6 Bll eae ae Gee ee TIZ0 — .3 —3.4 ER a SNE ara, 2. 0 «ois stecale si'ehe wes 13.0 —1.8 +3.3 98S ok re eee A ESP —3.9 —3.1 Payee Aa ticle oss Chee hes 14.3 —2.5 oa ot piet ie “ie eek et age aie SESE Ee a a 13.9 —3.3 a: Bet 1 de OO ee 16.6 —3.3 + .7 Nei ine Mirycioe Pa Py aa 10.? —2.1 Stat ein, ade ete erate at eee cs. BBecees ae 10.9 — .5 + .4 ad Sale a feokrn she Seeletae ate ne ats Tie + .3 — .9 APP Oe nce eerie os oe 12.0 +1.3 +2.3 } hglgne Wiel eels, oe Aa she ies os oes 10.5 —1.0 —3.6 SU ee re She Meee 9.8 —1.8 —1.5 AG ee ic > 2 Bos cbr 10.0 —2.5 —2.7 BIN i gal ol ok, « CR a eke eer T3i +1.9 —1.5 eee te Sh) as ied ch Nous Ate OE I4.3 —2.4 —1.3 hid Sha Pain SAR ater 10.5 — I —2.7 “lacs daly, Sateen Saeeaeaeaes oe! 12.4 —2.1 —2.1 1 A EMAL dies yp: Cae SPR ape dale oe 14.0 + .6 —I1.2 (1h 3 ae eee T4 nf — .4 ide “ha: 3 A, ean 10.4 “52 —2.6 a A re 13.2 —3.9 —1.6 Men OES Ieee ee ee 10.9 —I.5 —2.2 STEPS 26 ss apis ds es cee ee i023 —I1.2 — .6 Measurements of Mechanical A bility Identification Number Ge 6 a Fee 64 eS bl © Letra wb re © a wT we a a6 we & © to 6 eo eh ee is Wels ed @ 6 0 Oo 810m 6p Wie e 0 Bw o's ele one C40 6 She B® © iw Ste B06) 6 a ere mie « Bw eo 6) ve 6 6 fee © DS Be me 16 0 6) 6 6b a 10) 6.16, 6. O.6 Siw ie em Ae te. Be ale means ays © 6 a OG 6h e 6 #06 (sc 8) a oF el «ecm 6 & (7) bh .0 6 lelGre 6) 616) 6 fe 6.0 Ue) © 6 bln ie volte oo (© 6 @ B10 a Sb 616660 eo 000. © 2.8 0 oS ela Beale, & We. ee 6 OOM RS hel ee Uae e660 @ 08810) O06) © 0! Gia eke tae © 676 ve ® ele v6 6)0'0' #.6 O10:6. is \eimle we 8 + o 16 * (6 428 6 0» 6,e eye 6) 6)01 6 4.” & <0 0:8 Ww 6 ie 8 60 8 6 8 wee) 0 ie a8) 0 4 wl 8s ele, 2/00 * © 00e 6 6502 0 0 8ine 0 6m © a6 oF @y'e bes be 6, Big, 0 sic aww fe wees coe eeceareeeeeouereeecee Swe lee o Glee ard) we (lee a) @@ (0 6.618) 6 oe ye) 6) fh V6) ware Bete Ay. .& fee else 616 eee er ee eeeeer es eee evrevens 6 eels @ © oe 6 6) eos & ne Oe 8 0 eo Sigel rh Oe 6 @. Wh6 oO eW@ Le eee! ere je, a 6,0 Be 4 6) © 4 109) 6 en! lee ele 6 616 » ee ee ey O95. ave) we 16; 018 ee (9 ef) e..8/8w ee eee bie \¢)'e. 9 0'@ ‘pi 0m /0 4u a wie! wie) e018) 2 Cie) 1c. S 8 6 PB) Cl 0 6 ew sere eis) & bie sims eh BMC ©. © 6) w6\ ee 6m Oe) 6.0, 6 #8) \ 6, oS lal Se in eel eo ws sie /b.6 ed, 2 pis id! (¢/, 8) 18 (9) 9S 6 Be # 6 658 1018 (8 ew 6 a © uae! eco 6 8s, 0 6 es» Cig 610 0 pee ce See) ee ww Oe ea he wipe oO) & 0) '6 Ve 6.4) id. 6. @ fo @ A) SO. 8 10-19), bie 0 6 O68 OSES .e bh SB, Fs BOW eels @felg av) ene aye 6b. Vb) ae 60 eae Rie ele lols bo Oy See! 0 oe War @ 476) e.e wine je) site) » te o. 6 0 4) ole el 19, O10. (h Ol 8 6 16 wisielle. ap o 40 B86 SP SLs oe @ 3 ec bie ele (> «0 6 aime Whe w bie 618 Sie 9 ‘0 oie. A Sem ie) © (e o 2 ©) e @ 6 Ge) 618 Ace, Se 1 ee a e186) Bitte 6° m 8 OFO O10 e 66) e/etenere i@ 6.0 sb © ee eke (2 0) 6.9) ©, © oes ae el ele a als $y ewe (6:4 6) \0 0.0 ee) mw ate, ele mb me ee © a) 6 6m 6 O90 dee ec he a 48 Se Sie 3 lols 5) dS 8) 6.6 0 6) 8.0.6 61s lela ee) = We 6. 8 10 p16 S 8 he © Be 6 we \plenetp ie fol Bie wiley aE Sep (9) O10 6 © ele oie) 0) oa! ee BO eee a Oe O66 6) 818) Sica tee wae 6 ae % 6 0.8 6) ©) om 6.9) 8) 6 0.6.6 ir pe 19) « ele TABLE II—(Cont?'d) GIRLS Age Used in Com- puting Under- Ageness Estimates Lal La] NnNOoOCnUW © NUOhwW i ha °o .) Ve) - lo He -Romome -) MW CwNH wOOWR wih oO lo meat NRHN OW © HO ORN Lan! Lal OR NV Y Under-Ageness in Three Tests of Ab- stract Intellect Com- bined. (+ Equals Over-Ageness) | LI ONDOnD | ONAUNDA N AKUMA Awo~ar.8 a: | | | pe Perc ae? a Bags eee weg ey OM Roa) CORWE WRUNG BWRHACR BSHHND CHIHD 4: Ans ow Under-Ageness in Mechanical Test. (+ Equals Over- Ageness) | >) RO HH Ob ~I MOISCA Annan | peed NWR H | | ies) . HUAAWW += RWON | sheath > WO: hy =P cel ICNP hROHD | woo! | A Description of the Tests 15 above average in it also, but there are many chances for him to be below. It is clear that mechanical ability is not measured by ordinary paper mental tests and that it is worth while to further develop the type of test materials here tried out. With this in mind a second series of models was accordingly designed and tried out. This series is called Original Series IT. SECTION VI CONSTRUCTION OF ASSEMBLING TEST—ORIGINAL SERIES II Experience with Series I indicated the need for a series of more difficult models, in order that the test might be extended upward into high school and college grades, and also the desirability of more substantial boxes. Accordingly, after much search for suitable models six considerably more difficult than Series I were selected. These are shown in Fig. 2, together with the improved box. I. MODELS INCLUDED IN SERIES II The models are: Model H. Two straps buckled together in a complicated way with two buckles, four slides and two rings. Model I. A wall electric switch. Model J. A large rim lock. Model K. An ordinary electric bell. Model L. The works of a pendulum clock. Model M. An electric light socket. As in the case of Series I, a duplicate model not fully assembled was included so that the problem here, as in Series I, was frankly one of copying each model by building up a second model from the parts. In this series each assembled model, together with all the parts of one disassembled model, was placed in a separate com- partment provided in the special reversed box, and not mixed as in Series I. : This improvement eliminated the miscellaneous sorting of parts, although, of course, it also eliminated that feature of the test which called for identification of the particular parts of each model out of the entire mass of parts. But this sorting process, while no doubt a valuable test in itself (later tried out in a different way—see Recognition Test, page 21) was not the kind of reaction which was sought, besides it is wasteful of time. The object 16 ; ‘[][ SOMas [eUISIIQg *% “DIY A Description of the Tests 17 here was to test more strictly for manipulative skill. The cover of the box was designed to open toward the person being tested, to form a tray in which to work to avoid losing parts. A large and small screw driver and a pair of tweezers were included in this set. The test was given in the same manner as the preceding Series I, except that at least 50 minutes were found to be necessary. 2. METHOD OF SCORING The credit given for each model, when perfectly or partially assembled, is shown by the standard score sheet below. After the test the scorer examined each model and entered the score on record sheet which had been signed and placed inside the box by each person examined. The models were then disassembled to be used again. Boys who scored high in the tests were found to be ideal helpers. CONSTRUCTION OR ASSEMBLING TEST—ORIGINAL SERIES II STANDARD SCORE SHEET Grade All Models on a Scale of 0 to 10 Mover H (Strap) Score or Deduct BERET TONNE Pe tucson) Os Vie BR sk feed hens a < oom, peatiier tran Tevereed 01,5 «dU AMEE uh o's 5. ee e's sees 8 RATIO DAR VOTE Ct SOE ak ties UK a rice 6 SeuErOHCIe Wie Il aly WAY 20). 047 ec es. Alcw ne a ded: a Eee ILL Or, Wrong, fOr CACM (ant poh iis ne ae + 5s 2 IRE ee eI ok.) oc Son ee tied Sik gee es cde: ITO Mope I (SwitcH) INO Sitters 7c na. aie Biioe cee ee ob sO. we oO One contact wrong or omitted... Both contacts wrong or omitted. .... Bracket Wrong ci pchea cea ee ee es die oe eee oes 3 SRELIOCE ST, Vy 3. «1s SG EE TE Gi antes din eh hi ins se Wiltewrada lL oor MopeEL J (Rim Lock) No attempt. Seats Spring loose, Nae Over tepicttea helt GE rare a oe. Ae er Spring all wrong or omitted. ali. Be gee BRN st, 5 Revolving cam not oa, in eaietting ath carck i ihaien elS OD et EE RR ES SEA REO Bs ee ena ys ORE ee eRe? 10 18 _ Measurements of Mechanical Ability MopeE.L K (BELL) INO AEDES DE. Aksiooe & ae Meine alan peice iets Gop e Ser Wires wrong with respect to washers, for each.... For each washer omitted or misplaced. . For omitting or misplacing small square nocierione each. For each case of wrong screw used...............0..00- The whole thing about half solved.................... MopeEL L Nair No attempt. ae a 21.6 wo For works parity Assembled Allow for Beh Binion in nalace We Works all assembled but top frame not in place..... PReteet (ORO aa ni A ns 1D ceberanars (eee ibe eRe Novattempti. ay as neste eis GMD nian Senn tery ante Lower disktinvertede ux irc ons see ee eae ae Upper disk invertedtes (0) GA ae ee a ae Small nut omitted or misplaced... For omitting small black center pin bearing........... All properly assembled but no tension in spring... . This model frequently occurs in a very mixed-up condition; in such a case judge as to whether the whole effort represents that the problem is one-half, ee a i” one-fourth or three-fourths solved and grade accordingly. NotE—There will be cases where the degree of achievement does not cor- respond to any of the values given. In this case the obvious procedure is to judge it in terms of the case most like it. TimME.—The standard time is 50 minutes, although this has been varied. 3. RESULTS Records were obtained from the following groups, the highest score possible being 60: No. Freshman engineers, Columbia (1915)... 35 Teachers College graduate students (1915) 29 Efficiency men, silk factory (1915)....... 30 Freshmen, Mass. Institute Technology (1916).. es 40 Freshmen and econ year, Moy encanart Tastitute (1996) calhy Wawa ae 58 The results soon demonstrated that the idea of utilizing these Too Av. 43-4 48 very difficult models is impracticable for school purposes. much time is consumed in both giving and scoring the material. It is too bulky and awkward to handle in classrooms. = Nom ms m= WH WH It is also A Description of the Tests 19 difficult to assign proper partial scores to a model that may re- quire 30 minutes and be greatly affected by luck. This series was accordingly never extensively used. The distribution of scores for 190 cases is shown in Table III: TABLE III DISTRIBUTION OF SCORES FOR EACH MODEL [ORIGINAL SERIES II, IN 190 CASES OF COLLEGE STUDENTS AND OTHER ADULTS} Score Model rrr 1 Otal fe) Iv 6-9 10 FISCSIOE) Ge ah ek as ee 3 7 47 133 190 PRS osteo) OY a eae Oe ca ar & 14 16 14 146 190 LIC Res ha neti oe 15 12 62 101 190 Rethiectria’ Bell igs aces Ss 19 32 65 74 190 EAECIOCIE) odbc ids Gas a ee 56 24 17 93 190 M (Electric Socket)........ 120+, |) ~29 15 26 190 The order of difficulty is shown to be approximately the order in which the models were arranged in the box, i.e., the order in the table. The frequency of zero scores is exactly in this order. The scores indicated above cannot be taken, however, as entirely re- liable for models L and M, asa large number of persons worked so slowly as to leave little or no time to try these models. The average time required by 35 freshmen engineers per model was as shown in Table IV: TABLE IV TIME PER MoODEL—35 FRESHMEN ENGINEERS H I J K i M Strap | Switch | Lock | Elec. Bell} Clock | Socket Av. minutes.... 7.4 12.5 7.4 12.8 9.2 8.3 A further group of 100 8th grade boys were later examined by Mr. Hazen Chatfield in a New York City public school. From these cases the distribution of each partial score was as shown in Table V: 20 Measurements of Mechanical Ability TABLE V DISTRIBUTION OF SCORES FOR EACH MODEL, IN 100 CASES OF 8TH GRADE Boys OF 11 EXPERT TEACHERS ” H I J K L M Score Strap | Switch | Lock Bell Clock | Socket hs 7 St, See 8 II 10 16 58 79 Ree Mp 19> Le pate 3 3 I a 3 5 7 MRR 5 Siding Cnc ae 10 12 6 ‘3 fs 5 2 to Ty cia, NG I I a 8 4 I PRAM vents eo) icy Sp ie 5 5 6 8 5 3 Rha! eee eee I O 6 5 4 2 PER 1h a See I 4 3 4 O I Tce Sere e re ys.§ 10 6 j I2 2 fe) BNE Cele, Be I2 4 7 I2 I fe) a Wray adel» Robs 9 2 29 13 I oO TORI eee ae 40 52 22 12 I5 4 100 100 100 100 100 100 Approx. Median SCOres hear: 8.8 10.0 9.0 6.7 O. aye This table shows that 58 per cent did not reach Model L, and 79 per cent did not reach Model M in 60 minutes. The total scores reported for each class are therefore largely the result with four models tried, which is a meagre basis for drawing conclusions about relative mechanical ability. The time for 8th grade boys should be extended to, say, 90 minutes, to obtain the benefit of all models. r) 4. CONCLUSIONS This series requires more time than is generally practicable in school testing, and apparently does not yield as valuable (per-unit -of time-spent) diagnosis as sets composed of longer series of easier models. It seems doubtful that as good a measure of this type of ability is obtained in 60 minutes with Original Series II as in 30 minutes with Single I or II (developed later). The labor of scor- ing is also greater in the former. ‘JSaT UOTTIUSOIDY «LOI i Bn ee Section VII RECOGNITION OF MECHANICAL DEVICES OR MECHANICAL INFORMATION ‘TEST I. GENERAL NATURE Following out more specifically the idea of identifying me- chanical objects and mechanical parts by name, a series of small mechanical objects ranging from the very simplest obtainable to those comparatively technical, e.g., from a common wood screw to the parts of a spark plug, were fastened on an 8 inches by 15 inches stiff cardboard, to fit into a flat cardboard box about 14 inches high. Fig. 3 gives a general idea of the appearance of this test. 2. LIST OF MECHANICAL DEVICES IN RECOGNITION TEST I The list of names which follows was given to each person to be tested. The subject was instructed to find the name of each article in the box and to write its identification number opposite the name: a. Bushing for packing nut of t. Fuse wire spark plug u. Gasket or washer for making b. Cabinet door hook hose coupling c. Carriage bolt v. Gimlet d. Catch for cabinet door hook w. Glazier’s point for fastening e. Central insulation for spark plug glass f. Center punch x. Glass cutter g. Common ten penny nail y. Hack saw h. Common washer z. Hinge 4. Curtain rod fixture at. Insulating plug for electric light j. Cotter pin br. Jam nut or first nut for top of k. Coping-saw blade spark plug 1, Cut nail c1. Lock washer m. Dowel screw dit. Machine bolt n. Drive hook et. Main body of spark plug o. Drill fi. Nail set p. Eight penny finishing nail gt. Packing nut for spark plug q. Expansion lug nut hit. Patent box or mitre frame r. Flat head harness rivet fastener s. Flat head wood screw 41. Picture nail 21 22 ‘Measurements of Mechanical Abthty ji. Pipe reducer bushing ut. Stove bolt kt. Plumb bob vi. Tar paper cap to prevent paper lt. Roller skate wrench and key from tearing m1. Round head rivet wt. Thumb nut ni. Saw screw x1. Wedge for tool handles o1. Shade fixture for nonrevolving yi. Wedge to prevent window from end rattling pi. Shelf stop or support z1. Trunk caster qi. Set screw a2. Window sash fastener ri. Small hasp b2. Window lift st. Soft solder c2. Window shade fastener, non- t1. Staple for small hasp revolving end 3. RESULTS WITH RECOGNITION TEST This test was given to 205 pupils of the Forest Park School, Springfield, Mass., in codperation with Mr. J. L. Riley, then principal, and Mr. W. R. Cole, in charge of industrial arts courses. The pupils had been divided into selected classes as indicated below. The average scores and average deviation of each, ob- tained in 30 minutes, were as follows: Average Score Out | Average No Grade Group of a Possi- | Deviation ble 55 20 ori OB upoys Regular TAcT Ses LOnsiy,. oe) 7B i Practical Arts 20.7 7.5 porcine Mehr ee Muy de. u Regular Manual Training 16.4 G27 By fig MEADS sy 9: i Especially Bright 19.8 4.9 22D AC eR STs Regular Manual Training 20.0 8.0 89 .......| 9B and 9A | Boys, Regular 28.0 6.5 60 ne plies Oeitas Regular 9.4 5-5 Of these, the Practical Arts group were boys who had elected to take the maximum shop work available, spending much more time in the shop than any other group. The Regular Manual Training group spent much less,—14 hours per week in the shop, —while the Regular group spent even less, and was composed of undifferentiated pupils. The Especially Bright class ie composed of pupils selected by teachers as able to progress faster than the others, being promoted at shorter intervals. The average scores for each group given above show that the ~ A Description of the Tests 23 task is too difficult for pupils of all these grades. Even the 9th grade has an average score barely over 50 per cent perfect, while the others fall much lower. As is to be expected, the Practical Arts group score slightly higher than the others of same grade, The grade progression from 6th to 9th appears to be constant, suggesting that the experience needed to recognize these 55 ob- jects and their names is gradually gained more and more by all as they become older. Judging from these data the average 9th grade boy knows about twice as many of these objects and their names as does the 6th grade boy. The Practical Arts 7B grade group scores slightly higher than the Regular Manual Training 8B grade,—a gain of one year. Original mechanical interest and ability, as well as the extra training, no doubt contribute toward producing this result. The girls’ scores show that the test is entirely too hard for 6B girls. But only very limited inferences can be drawn from averages of a single unstandardized test. To obtain checks on these scores the assembling test, Original Series I, was given to a number of the same groups. The number who took this test and average scores were as follows: Average Average ; ie. Fata: Sgn Score Deviation 2 ee eee 7B Practical Arts 73.0 7.9 By ae ee eo 7B Regular Manual Training 68.9 6.4 Li 7B Especially Bright 72.8 eee 29 thy, Reoeeorae 7A Regular Manual Training 65.2 14.9 The Practical Arts group again scored higher than the Regular Manual Training group of same grade, and were again followed by the Especially Bright group. This test, however, was found to be much too easy for these grades. The scores are therefore largely a comparison of the speed with which each pupil could assemble the models. 4. CORRELATIONS To obtain a still further check, teachers were asked to rank their classes in several school subjects. The order of merit in algebra, geography and literature was combined (tentatively weighting all equally) into one composite ‘‘school subject”’ rank. 3 24 Measurements of Mechanical Ability a From these three measures a number of coefficients of correlation were computed. These are shown in Table VI below. Since each group was unavoidably small, and ne essarily ranked by a different teacher, the identity and number in each group is indicated to avoid giving misleading figures. TABLE VI | COEFFICIENTS OF CORRELATION BETWEEN RECOGNITION TEST, CONSTRUCTION TEST ORIGINAL SERIES I, AND SCHOOL SUBJECT No. of Boys | Grade Group r= 19.2% Mute 9B Recognition and School Rank ~.08 20. oe ek 8B Recognition and School Rank — .39 Wy eee ey St ys 7B Especially Bright Recognition and School Rank .02 FO eee anata 7B Practical Arts Recognition and School Rank aat 16) eps 6B Regular Recognition and School Rank .O1 ZO 2vohnd eaR 7B Manual Training (Regular) Recognition . and School Rank A Tos acu feat 7B Especially Bright Construction Test and School Rank 12 TORO OTe: 6B Regular Construction Test and School Rank .08 TOM saute. cas |e Practical Arts Construction Test and School Rank — .08 ZO Deh cE ant: 7B Manual Training Construction Test and School Rank .24 DON an tien 8B Recognition and Rank in Manual Training — 31 by Pa ae a AV a 7B Especially Bright Recognition and Con- ’ struction Scores 55 TOF eRe ee 6B Regular Recognition and Construction Scores .42 LO othr sneenaeon 7B Practical Arts Recognition and Construc- tion Scores .22 Oras diate eae 7B Manual Training (Regular) Recognition and ; Construction Scores .19 TS eee, ee se 7A Practical Arts Recognition and Construc- tion Scores .49 BT owe es 6B Regular Recognition and Construction Scores .47 ZU cts uted 7A _| Manual Training (Regular) Recognition and Construction Scores ‘7k Kate ar Sarak ae 6B Girls Recognition and Construction Scores .26 A Description of the Tests 25 The groups being in each case small, the probable error is large, but the agreement between similar group correlations tends to obviate this. While the data are inadequate and the measure- ments crude, there is evidence that the true correlation between rank in school subjects and the Recognition Test is near zero. Between the Construction Test and school subjects the correlation is alsolow. Other data not here available indicates that it is not generally over .40. There is, however, some evidence of correla- tion between the two mechanical tests, but the coefficients are too low to be significant, the average of the coefficients here re- ported being 41.4. But while it is probable that there are similar elements in the two tests, mere inspection shows that the two tasks are of different character. A boy may assemble a dozen devices without knowing the technical name of any of them. 5. RELATIVE “‘COMMONNESS”’ OF EACH DEVICE One other tabulation is of interest, namely, the relative fre- quency of right answers for each of the 55 devices, or the degree of ‘“‘commonness”’ of each. On the following page is a tabulation of the numbers of right answers for each device—for 57 boys, arranged in order of dif- ficulty. The results are somewhat surprising in several cases. The hack-saw blade ranks second, while the coping-saw blade ranks forty-second. The roller skate wrench and key is the easiest of all, and the first one on the list, bushing for packing nut of spark plug, is the hardest of all, while the jam nut or first nut for top of spark plug is no more difficult than the window lift. The cotter pin is no more difficult than the glass cutter, and so on. RELATIVE FREQUENCY OF CORRECT ANSWERS FOR EACH DEVICE IN RECOGNITION TEST ARRANGED IN ORDER OF DIFFICULTY 57 Boys. 7th to 9th Grade Forest Park School, Springfield, Mass. Number Name of Device Correct ermeeccer: SICAte Wren aris Bess 5 tale al alba at eat 3 oe 50 MERSOCORTw DIAG eo ae auton ic ntna Gael tert orate ss 48 OE Set The gee BSD oy Ee Pom PR eA e Rename RAN 47 2 OE A i ARIAIRESS OS Coes tba REAP gt gk RA 47 26 Measurements of Mechanical Ability Name of Device . Cotter pin. . ae lees wae . Tar paper cap to apres paper ween tengene Pe ee 4 lst head wood ecrew eo ca, op ie ee ee ey ee ee > Common washers ts bac: oa ic eee ee ee ee ‘ Curtam tod Ireture ves oe ys eee a eee ee . Common ten penny nail. . 0 PRE TOEE, PEL SORRY Phe 2 . Window Imit.64 oho RA ee eee 2S ee J Hight penny finishing naile. J... peseacres )\ demas aa . Picture nail. ; : . Glazier’s mee for Fastening ee Window: sash fasténer’..34) ko tea ee ae eee gee . Gasket or washer for making hose coupling. ............ . Window shade fastener, nonrevolving end. . rey op Mette OTB hi tat Nl A dee eahis (Oh cet Nae es ~ Wedgeitor tool handles. 25. Syn. vain ce amet ee cee . Insulating plug for electric lighta22 os) 07 nee SPT DOD Sune Re er cae ee ee cee ee Ree pi FOUSCSW IEE. 727, 3.2L Tp eine A ee ee ee a CENTEr DUNCD ie Bak Rk oot ere noes Reno aoe eae mC abinet COOL MOOK, (225. sid hottest wonadesixtire 1Of NONTeVOLVING .ef1d y chose ee ee ee AUCSITIMIEL, Age BR coerce Se eles We cc vis Bae ot ERY CT a eet ee . Central insulation for spark plug....... Piekae Rata. wiGarnage Bolts. 207 Wes ei, os em nes rane Pelee SOTAPICU Gi SIAM RAST oe ric Me ee eee. Seren ee eee Wai bodyor Spark pltig 4. isc. wee otters. Ge eke cee : Catch for cabmet door hook: & eee 2s ee . Jam nut or first nut for top of spark plug... 4 REARS » Pott Soldering cAPee se ca cca oem ieee: TL ee re « Coping-saw: bladel/./ccy Gon) oo ee i ee ee BSW BCL OW or). ele aay Uk Una dans ee eel) pee dr SO SUDSEE SCTE W ics cde eae nek mee Unt Al eRe) ce ee ee Ry OtOVE: DOME 2 226 eV 2/2 ae at. cle ne ed g shelf stop Or SUPPOLts = wow lp lce see wa een eee ae Na chines boltei 2) on vce See Rgee hte ee ree ee mi DILL DAS vate ie-'a eo sits a nies heii, cote ee ee Number Correct 47 46 46 45 44 44 42 42 41 A Description of the Tests 27 Number Name of Device Correct AieLemrent. Dox Or mitre frame fastener. coon as ks ae ae a 9 q. Expansion lug nut. Pe oe 9 yt. Wedge to prevent wihiow Ere Patines 7 ji. Pipe reducer bushing. . i gt. Packing nut for spark ie ' 4 a. Bushing for packing nut of sore Bing 2 6. CONCLUSIONS While the results of the Recognition Test are interesting froma research point of view, they are of doubtful value in practical educational testing work. The experiment was largely to determine the practicability of the method, and while there is no doubt but that there is a certain value in this sort of a test, it has serious limitations, the most im- mer nek {Tb portant of which is that it does not give promise of measuring | general mechanical ability of the kind in which we are most in- terested, such, e.g., as is measured by the assembling tests. It is purely a test of certain technical information and, moreover, it seems very probable in the light of later results with picture tests that this kind of measure can be obtained with infinitely less labor and expense by the use of pictures,—and these can be increased in range almost infinitely, which is not possible with actual objects. The incidental educational value in the handling of actual me- chanical objects, of course, is higher than that in looking at their pictures, and for any purpose, misperceptions will be less frequent. Actual objects also afford a better basis for what may be called mechanical reasoning. But the range of objects is limited. It is extremely difficult to cover a representative field without having at the end an impossible collection of large and heavy objects, impracticable to manage. Its usefulness is therefore largely con- fined to the laboratory. SECTION VIII SINGLE MODEL SERIES Experience with the Original Assembling Series I and II showed that such sets must be made more convenient and more workable, if possible. It was accordingly decided to attempt the develop- ment of a series that would eliminate as many as possible of the faults of the former sets and add possible improvements. The faults were in the main as follows: The Original Series I was too easy, being adapted only for the lower grades, and was exclusively a copying test. There was no way to insure beginning with the easier models and progressing toward the more difficult ones, as all parts were mixed in one large compartment. Moreover, the boxes were of an awkward shape to handle, and being made of cardboard were not sufficiently strong. : ‘ The models of the Original Series II required an average of from IO to 20 minutes each for most persons. Thus in one hour less than six models could be tried. The element of luck entered into this arrangement, and it is particularly difficult to give just and proper credit for a few partially finished difficult models. The ° sets were also cumbersome to handle and the models difficult to disassemble. The boxes as designed were about 8 by 43 by 20 inches. ~ I. SINGLE SERIES I x After much search and experimentation ten models were se- lected,—each one simple enough to be solved by an average 7th grade boy in approximately 3 minutes. From the Original Series I those models which had proved most satisfactory were taken, and these supplemented by others, better chosen in the light of past experience. A smaller, narrower, though longer box was next designed,—a group of eight of which when strapped up for carrying are not materially larger or harder to handle than a suit case. In selecting models all that were not ‘‘fool proof,’’ easily scorable, and easy to disassemble were rejected. It was also 28 A Description of the Tests » 29 decided to eliminate the extra assembled ‘‘copy”’ model in each case for the reason that even simple objects would then im- mediately become sufficiently difficult to constitute a test. Moreover, it eliminated mere ‘“‘copying”’ and introduced what was believed to be a somewhat “‘deeper’”’ sampling of the kind of ability it was desired to measure. It also cut the cost nearly in _ half, made the test only half as heavy, and easier in every way to manage. The idea of using the cover as a tray was retained, but all tools except one small screw driver were eliminated. These purely physical features may seem irrelevant and unimportant, but after a considerable experience with this type of tests it seems clear that if any such test is not perfected mechanically so that it is easily workable by any competent examiner,—and is also eco- nomical of time in scoring,—it defeats its usefulness and is, for practical purposes, valueless. . The chief improvement hoped for in Single Series I, however, was increased measuring power, through a wider range of samples, better control of conditions, and the elimination of copying. The reduction of time to 30 minutes, as against 50 to 90 minutes in the Original Series II was also important since it made it possible to give the test conveniently within an ordinary school period. 2. MODELS INCLUDED IN SINGLE SERIES I The models selected were as follows: / Ordinary cupboard catch Six links of safety chain Three-piece Hunt paper clip Bicycle bell Wire bottle stopper Clothes pin Shut-off for rubber tubing Push button Small rim lock Mouse trap SOMO O WD The general method of scoring previously adopted was retained, in which each model perfectly assembled was scored 10 points, and partial scores assigned each model according to an arbitrary schedule of values ranging from I to 9. smerce 30 Measurements of Mechanical Ability Thirty minutes was found to be sufficient for at least 80 per cent of 6th grade children, and was adapted as standard. A perfect score in 30 minutes was accordingly scored 100 points. In addi- tion a speed bonus of one-half point for each minute under 30 which was not used was added. (This, however, occurs but seldom.) Fig. 4a shows this series in its final form after the models had been scaled. The instructions which are printed on the cover of each box are as follows: DO NOT) OPENRIUHIS BOX sUNTILATORD ODO RSG Directions In this box there are some common mechanical things that have all been taken apart. You are to take the parts and put them together as they ought to be; that is, you are to take the parts and put them together so that each thing will work perfectly. Do not copy what your neighbor is doing but work absolutely by yourself. Turn the box so that the hinges are towards you. When opened in this position the cover forms a tray in which to work. Do not break the parts. Everything goes together easily if you do it in the right way. Begin with Model A; then take Model B; then C;andsoon. If you come to one that you cannot do in about 3 min- utes, go on to the next. The person who gets the most things right gets the highest score. Preliminary Trials with the Single Model Series. Experience with this series quickly demonstrated it to be an improvement over the earlier ones. The extended range of models, each of which can be solved in a comparatively short interval of time (averaging from I to 5 minutes) was found to offer a better chance for mechanical ability to show itself. It afforded a better sam- pling of a pupil’s ability since he had ten chances instead of four or less (as was the case with the Original Series II) in a period of 30 minutes. The advisability of continuing the “single’’ model idea, that is, the eliminating of the extra assembled copy model was considered both on the basis of the administrative advantage, and on the basis of the resulting efficiency of the test. In order to test the “ULIO EEG why Ts IMIS OSU “DV. “OI + / ‘ Sy Vw 44 ul re FAR 5 7 A Description of the Tests 31 latter point a group of 62 pupils were given a special test as follows: From the twenty models later available, ten, which were of such a nature as to lend themselves advantageously to being dis- assembled as well as assembled by the pupils, were made up into a first series, called the ‘‘disassembling-assembling criterion set.” Here the pupils were first permitted to take apart each model, and, after this operation had been scored and boxes inspected, the pupils were immediately required to assemble the models which they had previously disassembled. This probably constitutes a more thorough test than either the assembling with, or without a copy model alone, but is of course much more laborious and costly in time. A single series of dif- ferent models was then given the same pupils, to afford an op- portunity for comparison. The correlation between these two tests was estimated from these results to be between .6 and .7, indicating a fairly high correspondence. In order to afford an- other check, shop teachers’ ranks were obtained for the groups in- cluded. Fortunately, it was possible to obtain the independent rankings of two such shop teachers, the intercorrelations of which averaged .g1, justifying considerable reliance in these ranks as criteria by which to judge a test. The correlations between the shop rank and each of the tests was then computed. Between disassembling-assembling and shop rank, r= .58+.06, and between assembling only and shopwork, r=.61+.06, indicating that the single series probably is at least equally as good a measure as the disassembling-assembling series. More experimentation should, of course, be carried on to establish more precisely these points, but it was not practicable in this instance. From the administra- tive standpoint the single model series are in every way advanta- geous,—unless it be that the opportunity for cheating is somewhat greater. But by ordinary precautions this factor was easily controlled. On the whole, therefore, it seemed justifiable to continue the further development of the single model series. 3- SINGLE SERIES II Following out the success with Single Series I, the next task undertaken was accordingly to form: a second similar set supposedly about parallel in difficulty with Single Series I. 32 Measurements of Mechanical Abithty This was called Single Series II. Here the attempt was again made to select only models which in the light of past experience seemed thoroughly practicable for this purpose. This means they must be sufficiently difficult to present a real problem, and yet be workable. They must be of such a size and nature as to fit conveniently into a series,—must not demand too much mere physical strength, nor special assembling tools, must represent considerable variety, and must correlate fairly well with the same criterion. | Particularly only those which can be very quickly dis- assembled should be included. In the preparation of this series one further step was taken than before in the search for suitable models. Certain stock commercial articles were partially remade in such a way that they can with this modification be disassembled and assembled; for example, a rivet may be replaced by a re- movable pin without destroying the identity and essential char- acteristics of the article. A screw may replace a rivet in the same way. This makes available many more models. As previously pointed out, one of the difficulties met in employ- ing physical objects of this kind as test material, as opposed to printed problems which can be produced at minimum cost, modi- fied ad infinitum, and reproduced at will, is that the former are lacking in just these characteristics. Thus, while the models selected seem commonplace when found, the task of finding ob- jects that will meet all requirements is considerable. A trouble- some point has been met repeatedly in the fact that articles of this - character are continually disappearing from the market, so that it frequently happens, after a model has been standardized, that it is ‘ unprocurable except at the exorbitant expense of buying new dies “6 or patterns, for ‘“‘making it up special.’”’ The most practical method of overcoming this circumstance has been to continually standardize new models in terms of old ones, so that a com- paratively large number of known difficulty are available. In ad- /dition a practice has been made of selecting fairly staple articles. One reason each model must be standardized individually is to af- ford units or models of known difficulty to be used as substitutes for articles unprocurable after they have been standardized. This introduces difficulties, but cannot well be avoided. Fig. 4b shows general appearance of Single Series II in its final form. ‘WAOY [eULT ‘[] Seles asurg “qh ‘Oly A Description of the Tests 33 4. MODELS INCLUDED IN SINGLE SERIES II The list of models as first tried out was as follows: A. Elbow catch F. Calipers B. Rope coupling G. Rubber stopper C. Toy pistol H. Four-piece paper clip D. Expansion nut ' JT. Double acting hinge E. Sash fastener J. Lock Preliminary Trial of Single Series II with Single Series I. Preliminary trials of this series indicated the models all to be serviceable. Preliminary scaling indicated also that they were of a slightly better ‘‘spread”’ or distribution as regards relative dif- ficulty. The two series were now given to some 300 pupils and on the basis of these data the further refinement of the material was undertaken. Asa preliminary it was thought advisable to check up the question of the contributory value of each new model. 5. CORRELATION OF EACH OF 20 MODELS WITH CRITERION The criterion here adopted was the total raw score in 20 models. With this each model was correlated with results as shown below for 50 thirteen-year-old boys. First SINGLE SERIES I A. aden CALCH aL. cake tes ores. Bes Clothes, Tith.:.janind ae eee .68 B. Chain. Seu eat emo Ram aa, (ECODEr NOSE yo). ie) tn eee AS C. Hunt paper ine ei Fee ee Ry ee CE Ee Tiett: LILCONLs a tira cae ee ah SE Dithirycie pel... seo. ee HON be SOCK ONG, 1a. oy vaeme Wee en ee AS E. Exp. rubber stopper....... TOU tie VWVITEIBLODDCE by is cau cet set he FirsT SINGLE SERIES II Fit RADOW CALEY ox nc! aia att Ce PD) EA Os 75 «USDA IMC on i Eeiraba (21 ig, W By ROPE COUDUINS ss. oi bes OO MILA RA OSCE cure lt Crime Gah 7 C. Pistol. be elo ya Ue inane de TOM Sepa ah ai A ats | .68 D. Bansrinien ant Mea Ahh ta Gee .64 I. Doublehinge. . 32 Sage ea i! Sash fasteners. Aewis,) tds CePA Zs SGN C2 Br), a Nea eee .48 While it might be theoretically desirable to retain only models correlating very high with this criterion, the practical considera- tion of the difficulty of obtaining suitable models made it seem advisable not to discard any model which had been found to work well in the series. Moreover, a low correlation with this criterion is no evidence for assuming a low correlation Pe other equally valid criteria. SECTION IX SCALING As in the case of Series I,! arbitrary, partial and perfect score values were assigned in Series II? for various degrees of excellence in attempted solutions of each model. Each model correct was counted 10 points, as before. Thus with the models roughly in order of difficulty within each set, and with these partial score values, a working method of scoring each individual was es- tablished. But at best this procedure is crude. The difficulty- distances between models are by this method unknown,—that is, the exact difficulty of each model, as compared with any other, is undetermined, and no account is taken of the form of distribution. However, in dealing with this special type of problem a large part of the task consists in the experimentation necessary to discover and perfect models, as well as in the special technique involved in managing them. A series of mechanical objects highly perfected, in so far as finesse in scaling and theoretical treatment is con- cerned, might still be impracticable and largely useless for actual work. But having previously taken up these points, and having selected material so as to meet these requirements, the next logical step is the refinement of the mathematical technique. I. A NEW METHOD OF SCALING: THE MCCALL METHOD In the matter of scaling each individual model to determine its relative difficulty, and in the scaling of each series as a whole, a number of methods were possible. The theory of scaling material of this type is not different from verbal material, except for pecul- iar items such as the short series of problems necessitated by physical limitations. But these are incidental. The literature of test making contains abundant examples of ways of scaling. In fact, it is the variation in methods and technique that is now most disconcerting, for since much of the procedure is arbitrary 1 See sample score sheets in Appendix. * For sake of brevity, and since previous series have been discontinued, the term ‘“‘Single’’ series will henceforth be dropped, all series being single unless otherwise specified. 34 A Description of the Tests 35 it becomes more and more confusing as each scale comes out, based on some new modification in procedure. Fortunately, at the time of this research a growing movement, fostered by Pro- fessors Thorndike, McCall, and others, has developed for the standardization of technique in the scaling process. Even > though that standardization be based largely on mutual agree- ment to adhere to an arbitrary procedure, the important thing is the agreement on some one definite method. In the interest of uniformity, therefore, as well as on the basis of the advantages incident to it, the McCall method of scaling has been adopted.! Advantages of the Method. As has been suggested, the chief advantage lies in the direction of adopting uniformity of method, making possible direct comparison of final scores for tests of vari- ous abilities. Just as a series of Fahrenheit thermometers used respectively for measuring the temperature of one’s bath, blood, room, automobile radiator, baby’s milk, etc., etc., will record the final results in comparable and meaningful units ¢(which-we-call ‘““degrees’’), just so it should be possible to compare units of any number or variety of mental abilities. Adopting a uniform procedure involves at least three important items: 1. The agreement as to a basis for scaling, that is, what grade or age should be used in determining scale values. 2. The agreement as to a common unit. 3. The agreement as to a uniform zero point, or point of reference. Scales have in the past been constructed on the basis of this grade or that, or on the basis of several grades combined. Units have been of all kinds,—the number of right answers, per cent right, probable errors or standard deviations of various grades and ages. Zero points have been located at practically as many dif- ferent points as there are scales. Professor McCall’s method proposes to standardize these points as follows: a. The basis of scaling adopted by mutual agreement by a number of investigators is the total distribution of children whose ages range from 12:0 to 13:0 years—no matter in what grades found. The reason for the choice 1Wm. A. McCall, How to Measure in Education, Macmillan Company. Also Teachers College Record, March, 1921. 36 Measurements of Mechanical Ability of 12-year-olds in preference to others is that it has been found through researches by Thorndike, Kelley, and others, that with this group a more normal distribution is found than for any other age, since this group is least affected by the factors of school elimination. b. The standard unit adopted is one tenth of zr S.D. of the 12-year-old distribution, which unit McCall proposes to call ‘“‘'T”’ in honor of Professors Thorndike and Terman, early advocates of some such standard practice. c. The standard point of reference is to be the mean 12-year-old, with the zero point arbitrarily (but apparently reasonably) located at 5 S.D. below the mean. Scale values thus defined will henceforth in this report be referred to as “T-Scale”’ values. d. Each test scaled as a whole. The important departure in this method is that the test is scaled as a whole. Each possible “‘number right”’ on the whole test—no matter which elements are included—is given a difficulty value, first in terms of “per cent of 12-year-olds who exceeded plus half those who reached”’ that partial, and then, to take account of the form of distribution, this percentage is converted into the corresponding S.D. value of 12-year-old by means of a table. Sucha table appears on page 44. The two extremes of this table, it will be noted, represent such minute percentages that in practice the ends of the scale are never actually reached. The table will, of course, be recognized as a representation in round numbers of the normal surface of frequency, whose two extremes are infinite, but are here arbitrarily placed at —5 $.D. and +5 S.D. For most scales the table range will lie between, say, 15 to 20 and 75 to 80, and this is a sufficiently large range to provide adequate differentiation. McCall has thus adopted the methods employed by Bucking- ham, Trabue, Woody, and others, for determining the difficulty of each scale element, to the determination of the difficulty of each possible percentage of right answers for the test asa whole. This ignores the relative difficulty of each individual element as stressed by previous scale makers,—except for the general recom- mendation, advising placing the elements in the general order of difficulty for all grades to be tested, to best insure that the pupil will attempt all the problems which he has any chance of solving. The method takes advantage of the fact that because: a given element is most difficult for the greatest per cent of pupils in general, there is no certainty that it will be most difficult for any particular pupil. Some other element may for him be the most difficult. 7 | The method avoids the more or less precarious and especially laborious procedure of measuring inter-grade distances which is based on assumptions which have never been adequately sus- tained. It is also much simpler than the former methods, and A Description of the Tests 37 makes it possible to standardize easily many achievement tests in terms of T-Scale values. It avoids the other laborious and somewhat involved 20-80 per cent method used by Thorndike, in scoring the Alpha Reading test or the 50—50 per cent method used by Kelley in the scoring of the Kelley-Trabue Completion Ex- ercises. 2. RELATIVE DIFFICULTY OF EACH MODEL The next task would then logically be to determine the T-Scale values of each possible number right for Series I and for Series IT. Before doing this, however, it is necessary to examine more closely whether the order in which the models were at first placed in each test is in accordance with their real difficulties. To enable us to observe this point the percentage of correct answers for each model for grades 6, 7 and 8 were computed with their S.D. equivalents. For convenience all the models, that is, both Series I and Series II, were thrown together and all the results tabulated in Table VII. A glance at this table shows at once that the most striking fact is the similarity of difficulties for all of the 20 models, for any given grade, or on the average for all the grades. It means that the 20 models,—selected on the basis of personal esti- mate as being of a variety of difficulties, are really not very dif- ferent,—the total range of either series being (on the basis of the average difficulty for the three grades) only about 2S.D. Fig. 5, showing this fact, also shows that there are ‘gaps and bunchings’”’ of the models of each series, with Series II a little more difficult on the whole. Theoretically, it is desirable to have a larger range in scale values, but in this case we must keep in mind that there are but ten elements, and to spread ten problems out over a long range of, say, 4 to 6 S.D., results in a very ‘‘thin”’ scale, with great unreliability at any one point of the scale. There is, therefore, a justification for accepting the series as . they are, rather than beginning again and substituting, say, three models much easier and three much harder than any at present included, to produce a larger range of difficulties. Ten scale elements grouped fairly close together tend to eliminate mere “luck’’ scores, since the opportunity is provided to try more than once, at about the same difficulty. So long as the number of zero or perfect scores for the whole test is negligible or small it is likely that the final score is more reliable when based on such a group of 38 Measurements of Mechanical Ability models than it would be in the proposed long and thin scale. While the range of difficulties is short, the ten tasks are by no means identical in difficulty, and less so in their nature. We might actually have a scale of ten elements of identical difficulty and identical nature and yet obtain a measure by considering the speed score. This, of course, is not our purpose here, although account is taken of the speed, and hence the score is partially in terms of it. The differing nature of each model makes it TABLE. VIE PERCENTAGE OF RIGHT SCORES FOR EACH MODEL wITH S.D. EQUIVALENTS Zero=—5 S.D. N=Sertes I: 452, Series II, 459 8th Grade 7th Grade 6th Grade pela Ah IE PBS aa a Aver Model Per Per Per Se 5.D. 5.D. Cent 5.D. Equiv ee ee Eee AS Re Cupboard catch .| 665 457 714 443 560 485 | 462 Catia ye.) 286 557 220 wer 203 583 572 Hunt paperclip..| 340 541 300 553 252 567 554 Bicycle bell.....| 243 570 || 9422 577 185 590 | 579 Expansion rubber Stopper: hey wich 182 591 134 611 147 605 602 Clothes pin..... 445 514 | 464 509 318 547 523 Rubber hose....}| 231 574 249 568 34 611 590 Push button ....| 206 582 131 612 096 631 608 Lock Nati... 142 607 114 621 062 654 | 627 Wire stopper....| 231 574 168 596 086 637 602 Elbow catch ....| 525 494 | 562 484 | 380 531 503 Rope coupling...| 695 449 592 477 202 583 503 DIStolee sche 61 472 615 471 386 529 | 491 Expansion nut ..| 51 497 | 562 484 | 228 574 | 518 Sash fastener....| 251 567 266 563 189 588 573 Gahiperso. i. Pte ly, 128 614 146 605 ae: 632 610 RP TAD eo ae yams 105 625 115 620 028 690 645 Paper clip No. 4] 146 605 115 620 | 050 665 | 630 Double hinge....| 073 646 | 094 632 027 693 657 BOEKING! 20 h7F 1050 665 023 700 a: 741 683 Totalace vor 11,201 EE,323 12,136 AVETAIE) 201 Vane 560 5 ack 566 ome 607 A Description of the Tests 39 particularly hazardous to attempt to say that the mechanical ability of a certain boy is, say, 30 in Series I, because he can assemble the cupboard catch, clothes pin and Hunt paper clip, but not the other models. In Series II he may score 60 because of special experience, and the accidental nature of the particular objects included. It very frequently happens that three difficult (as by this determination) models are solved and many easier ones (as by this determination) are not solved. This, of course, occurs in other scales as well, such as reading scales and language scales, but not so frequently because there is greater uniformity and continuity in the nature of the scale elements. It was partly to provide some statistical method of interpreting such scores that the 20-80 per cent and 50—50 per cent methods previously referred to were devised, and partly to provide a simpler method for ac- SERIES I SERIES I1 n * 462 n #459 Lock #2 } ; Trap Double Act. Hinge 4 \ Lock #1 Push Button Wire Stopper Shut-off Bicycle Bell Chain Defiance Paper Clip Calipers Exp. Rubber Stopper Sash Fastener ak Exp. Nut Hunt Paper Clip Clothes Pin Rope Coupling & Elbow Catch Pistol Cupboard Catch i V Fic. 5. Scale Difficulty Distribution of Models for Series I and Series II. Av. S.D. Difficulty Values for Each Model for Grades 6, 7 and 8. 4 40 Measurements of Mechanical Ability complishing the same purpose that the McCall method was proposed. Before going further into this, however, the matter of the order of the models within both series should be settled. Fig. 5 shows that the order of difficulties is not the same as that determined in the beginning by the preliminary trial with a few cases. On the other hand, the differences are not very great. 3. OLD ORDER AND FINAL ORDER OF MODELS Following is the old order again repeated with the final order for both series: SERIES | OLD ORDER FINAL ORDER A. Cupboard catch Cupboard catch ™ B. Chain : Clothes pin « C. Hunt paper clip Hunt paper clip ” D. Bicycle bell Chain-{ E. Wire bottle stopper » Bicycle bell \ F. Clothes pin | Shut-off , G. Shut-off | Wire stopper H. Push button” Push button 4} I. Lock No.1 Lock No. 1 } de LraO ae Trap SERIES II OLD ORDER FINAL ORDER A. Elbow catch Pistol B. Rope coupling Elbow catch , C. Pistol Rope coupling D. Expansion nut Expansion nut E. Sash fastener Sash fastener F. Calipers Expansion rubber stopper G. Expansion rubber stopper Calipers H. Defiance paper clip Defiance paper clip I. Double action hinge Double action hinge J VLOCK No, aan Lock No. 2 It will be noted that the shift in position is slight in terms of scale distances, as shown in Fig. 5. The question now comes up whether to leave each test as it was originally, in order to preserve its identity, which is desirable in the McCall method of scaling,— or to rearrange the models in terms of the final values obtained. It seemed best to do the latter. Shifting the position of scale A Description of the Tests 41 elements, however, introduces an error in that the difficulties have a tendency to change when placed in a different position on the scale. But the changes here made are so slight that it is believed no serious change in difficulties will result. In comparing the two scales in Fig. 5, it is clear that the spacing of both the scales would be improved by shifting models from one series to the other, and this could be done since all twenty models were given to the same pupils. But there is an objection to destroying the identity of Series I in that all other records ob- tained with it then would be lost. The chief body of data col- lected with this series was that obtained in the Army, where 14,000 cases were tested. This seems sufficiently valuable to justify preserving the identity of Series I, and doing so automati- cally preserves that of Series IT. 4. DIFFICULTIES IN OBTAINING CERTAIN MODELS In this connection an unfortunate circumstance, illustrating the ‘annoyances incident to working with this type of material, may here be considered. After all the records of the Army experiments — were completed for the 14,000 cases, with Single Series I, and the task of scaling and establishing norms for age and grade was taken up, it was discovered that two of the models used in that series were unprocurable because they have been discontinued by the manufacturers. The two articles in question were (1) a small bicycle wrench and (2) a coin safe for holding pennies, nickels and dimes. It was therefore impossible to preserve the exact identity of the series used in the Army, and the only possible alternative was the substitution of other models. Accordingly, this was done. For the bicycle wrench, which was Model A of the Army series, the cupboard catch of our present series was substituted, and for the coin safe, Model E, the wire bottle stop- per, as of probably similar difficulties. These substitutions must therefore be kept in mind when considering the Army series. In order to evaluate them the dif- ficulties were carefully compared. From data in hand the fol- lowing comparisons were made. For a group of 7th and 8th grades (supplemented by adults, as shown) the difficulty values of the discarded and of the new models were found to be as follows: 42 Measurements of Mechanical Ability OLD (DISCARDED) MODELS A. Bicycle Wrench No. Group Per Cent Right S.D. Equivalent 95. 7th and 8th Grade Boys ...... .516 220, ,, ooldiersiy (jae tr ee eke .525 A Verace saa Ghats okt 5200 Cah RESUS B. Coin Safe 95 7th and 8th Grade Boys ...... .408 220) Soldiers faa. gab es ibd a ea! .440 LS” Con, Rea ee 42d) osc a ae ge s 2” Average Difficulty of Old Models... .. . . 50.0 ef New Mopets - A. Cupboard Catch 544 7thand 8th Grade Boys ....... .689 .450 ‘ B. Wire Bottle Stopper 544 7thand 8thGrade Boys....... . 196 586 Average Difficulty of New Models............... 51.8 Difference int Diflicult ye. ey iets ot ec LO-LOte tao) Thus it is seen that the average difficulty of the two new models exceeds that of the old discarded ones by .18 S.D., or 1.8 points on the T-Scale. From Army scores obtained with the series, including these two easier models, this amount should be subtracted to make them comparable with the scores herein re- ported, which were obtained in the final series. This correction is of course only the most probable one. To substitute one model for another without altering the scale values as a whole would require perfect correlation and identical difficulties. All we know here is that the difficulties are reasonably equivalent (we have the estimated differences). The correlation of the four models in question with the total score was found to be for fifty cases as follows: Wrench with Total Score, 10 models..............7=.5I Coin Safe with Total Score, 10 models............r=.49 Cupboard Catch with Total Score, 20 models......r= .67 Wire bottle Stopper with Total Score, 20 models . ..r= .48 A Description of the Tests 43 5. T-SCALE VALUES FOR EACH RAW SCORE OF SERIES I AND SERIES II Having determined the scale difficulties of the elements of these two tests, and having arranged them in what seems to be the best order, we may now consider the matter of scaling each instrument asa whole. This is done by calculating from the distribution of the 12-year-olds the percentages exceeding plus half those reach- ing each possible raw score value, and then converting these per- centages into T-Scale equivalents, in the same way that elements of scales have been treated by other investigators.! The distribution of scores for the two tests as rearranged and scaled is given in Tables X and X. Because of the small number of cases of 12-year-olds, it was decided to utilize as a check upon them the scores of ages 13, 14 and 15. By computing the dis- tances between the median of the 12-year-olds and that of the 13-year-olds in terms of the percentage of one group which reaches or exceeds the median of the other group, and transmitting this into an S.D. equivalent, and then correcting all of the 13-year-old values by this amount, the 13-year-olds may be utilized as 12- year-olds. This of course assumes a normal distribution for all age-groups thus utilized. Ordinarily it is inadvisable to thus make use of neighboring age-groups, especially those more than one year removed from the 12-year-olds. In this case, however, no marked differences are discernible in the form of distribution for ages 13, 14 and 15, and since the number of cases is small it was thought best to utilize all of the data. The exact method followed in Tables IX and X is as follows: The S.D. scale values, with —5 S.D. as a zero point, were de- termined for each age group exactly as for the 12-year-old group. The distances between the 12-year-old group median and the median of each other age group were then calculated by the per- centage of overlapping method. Thus the percentage of 13-year- olds who fell below, plus one-half those at the median of the 12- year-olds, was found to be for Series I, . 26. Reference to Table VIII shows the nearest S.D. equivalent in round numbers to be 56.55.D. Subtracting this from 50, the midpoint of the 12-year- olds, gives a difference of 6.5 T. That is, the difficulties of at- taining each of the various numbers of models right for the 13- * Buckingham, Trabue, and others. 44 Measurements of Mechanical A buity year-olds is on the average 6.5 T less than for the 12-year-olds. Similar differences have been computed for each age-group and utilized as a ‘‘correction.’’ Adding this correction to the S.D. values of each age group we obtain the 12-year-old equivalents. That is, the older groups are thus utilized as 12-year-olds in order to increase the reliability of our data. By taking the averages of TABLE VIII S.D. DISTANCE OF A GIVEN PER CENT ABOVE ZERO; EACH S.D. VALUE Is MULTIPLIED BY 10 TO ELIMINATE DECIMALS The Zero Point Is 5 S.D. Below the Mean S.D. $.D S.D S.D Value Per Cent Malge. 4 hon GeDt | ervatyen [ener Cent Value Per Cent oO. 99.999971 25. 99.38 50. 50.00 75. 0.62 0.5 99 .999963 25.5 99.29 50.5 48.01 75-5 0.54 TE 99.999952 26. 99.18 flee 46.02 76 0.47 1.5 99 .999938 26.5 99.06 51.5 44.04 76.5 0.40 2. 99 .99992 27. 98.93 52. 42.07 77 0.35 2.5 99 .99990 27.5 98.78 52.5 40.13 Lie 0.30 Zi. 99.99987 28. 98.61 te 38.21 78 0.26 3:5 99.99983 28.5 98.42 53.5 36.32 78.5 0.22 4. 99 .99979 29. 98.21 54. 34.40 79 0.19 4.5 99 .99973 29.5 97.98 54-5 32.64 79.5 0.16 5. 99 .99966 30. 97.72 55. 30.85 80 0.13 5.5 99 .99957 30.5 07-44 55.5 29.12 80.5 oO.11 6. 99 .99946 31. 97.13 56. 27.43 81 0.097 6.5 99 .99932 83045 96.78 56.5 25.78 81.5 0.082 P(e 99.999I5 32. 96.41 tty 24.20 82 0.069 7-5 99.9989 32.5 95-99 S75 22.66 82.5 0.058 8. 99.9987 33. 95.54 58. 21.19 83 0.048 8.5 99.9983 33-5 95.05 58.5 19.77 83.5 0.040 9. 99.9979 34. 04.52 59. 18.41 84 0.034 9.5 99.9974 34.5 93.94 59.5 17.11 84.5 0.028 Io. 99.9968 35. 93.32 60. 15.87 85 0.023 10.5 99.9961 ake 92.65 60.5 14.69 85.5 0.019 Poe 99.9952 36. 91.92 OI. T3a57 86 0.016 Ers'5 99.9941 BGa5 QOI.15 61.5 I2.51 86.5 0.013 I2. 99.9928 sti ie 90.32 62. II.51 87 O.OII r2.5 99.9912 37 25 890.44 62.5 10.56 87.5 0.009 DSi 99.989 38. 88.49 63. 9.68 88 0.007 L325 99.987 38.5 87.49 63.5 8.85 88.5 0.0059 I4. 99.984 39. 86.43 64. 8.08 89. 0.0048 14.5 99.981 39.5 85.31 64.5 7-35 89.5 0.0039 15. 909.977 40. 84.13 OB 6.68 90 0.0032 I5.5 99.972 40.5 82.89 65.5 6.06 90.5 0.0026 16. 99.966 41. 81.59 66. 5.48 QI 0.0021 16.5 99.960 41.5 80.23 66.5 4.95 91.5 0.0017 Lig 99.952 42. 78.81 OF 4.46 92 0.0013 17.5 99.943 42.5 77.34 67.5 4.01 92.5 0.O0II 18. 99.931 43 75.80 68. 3.59 93 0.0009 18.5 99.918 43-5 74.22 68.5 3.28 93-5 0.0007 IQ. 99.903 44 HLA 69. 2.87 94. 0.0005 19.5 99.886 44.5 70.88 69.5 BAT) 94.5 0.00043 20. 09.865 45 69.15 70. 2.28 95. 0.00034 20.5 99.84 45.5 67.36 7025 2.02 95.5 0.00027 Gh Os 99.81 46 65.54 7 Ree I.79 96 0.00021 21.5 99.78 40.5 63.68 7 feel Ix5S 96.5 0.00017 22% 99.74 47 61.79 yee I.39 07 0.00013 2275 99.70 47.5 59.87 72.15 L422 97.5 0.00010 234 99.65 48 57-93 73. I.07 98 0.0008 23.5 99.60 48.5 55.96 7325 0.94 98.5 0.000062 24. 99.53 49 53.98 TAs 0.82 99. 0.000048 24-5 99.46 49.5 51.99 74-5 0.71 99.5 0.000037 Brapanel SAEED Gatet eke Peak Nat MMT Ane Secs. 2) | Uae T OR ets RS Aan Cad CVn 100 0.000029 A Description of the Tests 45 TABLE IX ASSEMBLING TEST—SERIES I T-SCALE SCORES FOR EACH NUMBER RIGHT. WITH PERCENTAGE OF EACH AGE Group WHO REACH OR EXCEED EACH SCORE Total Number of Cases—1,361 Ageiz2 | Ager3 | Agerq | Age 15 Pkeayy No. of Problems T-Scale Right X10 Score Per Cent | Per Cent | Per Cent | Per Cent | Per Cent Exceeding | Exceeding | Exceeding | Exceeding | Exceeding + One-half} + One-half} + One-half} + One-half} + One-half Reaching | Reaching | Reaching | Reaching | Reaching TCO ES ere ae hee 24 99.6 fe) re) 00 100 REO Sirk late he eters 30 98.7 r¢) 99.8 r¢) 99 ASUOs Sihcisiaie ts oes 31 97.3 99.6 06.8 te) 99 ORTON Pace oe ieee a O50 i 98.8 95.6 99.5 99 STO 30 ae iiges s copes 35 91.9 97.6 94.8 99.5 99 TOSCOAT Ec iron nia 38 88.8 94.0 93.6 07.4 98 ESOC DS i wee, eens 40 85.2 90.8 OI v2 94.1 97 Tt. COu Loe tate. es 42 81.6 88.7 87.9 Oras 96 50 (GL EFE as cee 43 78.9 85.9 85.1 890.8 95 TS tOutOr. fois. sh 44 7Sind 82.3 82.3 88.2 95 20 tOPSIe so eee 45 Ghee. LIAS 80.3 86.6 94 SCO; BSE eerme ene 46 O72 77.9 78.3 85.5 93 BAy CONES e sive ee woe el 47 G25 73.8 75.8 83.4 92 20 COUA7R ee ote 48 58.1 TA ane 81.2 QI 28; COndOU a tes 49 55.0 69.0 67.8 Out 90 SO tO8STe. ee 50 49.6 62.9 65.4 95.9 88 PICO eae re eae 51 43.3 57.7 63.7 ays 87 SALONS S i Oe ea ee 52 sO 54.9 60.6 68.5 87 SGRCOT SUE Was eo acted ig 32.9 51.6 56.9 65.6 87 SERLO” 40%": antas asians 54 28.4 48.0 54.9 63.0 87 AONUCG) Alas cs ele iter 55 23.9 45.6 51.6 61.3 78 AP AOCAS Re. os fe 8 56 20.8 43.2 40.8 58.1 75 AATUG AS es sd t= CO Py | 18.5 38.7 42.0 54.4 72 AOLCOBA GT Oe 5 acces 58 16.7 Baar 37.9 52.2 69 BSLLOMAQ) ca ar- 5 cs 4.54): 59 14.5 28.7 35.9 Raghie 66 SOSLOES Cte cs actos 60 ba ae 25.4 33.9 47.9 63 Ere Wh te eras epee ae 60 9.0 22.6 STEE 44.7 60 RANCORG Sere eae. ca cnths 61 9.0 19.8 20515 42.0 57 BROMO Sif te mae ete aie a 62 742 Wee 28.3 42.0 54 SSutGeSOu cee wrcite my: 62 7 hor: TOMs 2erh 38.2 51 GO tOLOTE: cece kus: 63 Eee. 14.5 22.6 35.0 47 OP ICO OS ate a eine 64 SA I2.9 22.6 31.8 44 OARtOROS cer. oe cee: 64 5.4 Lies 19.0 26.9 4I OGGEOL0 7. ore ee: 65 sat 9.7 19.0 22.6 38 OSi:t0 CO 9 sn 2. eyes 66 4.1 8.5 16.2 20.5 35 A Yast 0 tr ty Gey 3 oe ee et a 67 ee | 7 hak TQ7 E723 31 721 OR 73h ae Cols 68 232 HaR 1H ONY 13.5 28 SA LOFFS 2 ae re 68 ye | Oat TOnr 10.8 25 AO SCOm 97) eta. cena 69 Baw 6.1 8.5 S7, 22 9S 5tO. 70. aot eee 70 2234 Sas ery Sea 19 SO. t0uST2 2. renee 72 r34 5.3 257 6.0 7 82.:£0' 83's eis Sek oie 74 A Chay 2.9 3.8 14 S43t0/ 85556 - stad 74 Pan a7 2.0 3.8 II BOOB 7s dee ee ee 75 2.4 Le 3.8 9 BS tO S03 4 on8 sei ce 75 AY} Tia Bind 7 DOLCOL OL keisha aan? 79 8 ree ne 6 MEZA AiG les i a ciate 80 8 afl Ue 5 SP ETO INR AS & Ae tele 80 fies 4 OOLEORO Fi. «chide aac 81 3 GOEL OO saan ec. 81 2 cou tele toe CA sae Renae Rae 82 I EGAtOP LOS 25s + wes 82 snete PO ALT HIOS oy aes esis 83 PAMINGOLLOT 5 Winis es 4). 83 TOG7107100 «25h. 50's 84 IN a VEN RG 46 Measurements of Mechanical Ability TABLE X ASSEMBLING TEST—SERIEsS II T-ScALE SCORES FOR EACH NUMBER RIGHT, WITH PERCENTAGE OF EACH AGE Grouprp WHO REACH OR EXCEED EACH SCORE Total Number of Cases =450 Age I2 Age 13 Age 14 Age 15 No. of Problems T-Scale Right X10 Score Per Cent Per Cent Per Cent Per Cent Exceeding Exceeding Exceeding Exceeding + One-half | + One-half | + One-half | + One-half Reaching Reaching Reaching Reaching 0 to I 27 99.6 99.6 te) (9) 22tONS yore ars 29 98.7 99.6 00 (3) A» CONS ner: 32 97.0 98.8 99.6 99.0 6) toe7. 35 94.0 97.6 98.8 96.9 BtO Oey ee ee eee ay 91.0 97.6 98.0 O5 ea TO: CORTE Shae ee 39 87.5 94.8 06.4 O37 12 tOMLS VL eee 41 84.1 91.6 93.6 OS TALtONIS LEY ode ee 42 80.2 91.6 Ola 92.2 16. tO3072 4 ee 44 ao 890.5 88.3 90.0 T8touLos 45 fits) 86.2 85.1 87.9 20 \tOM2 Tia sepshaaie ae 46 66.0 Bens Srey 86.9 22° tOG23\ tone 47 60.8 83.1 76.6 86.9 24 1025... 48 56.1 fetes EO 85.8 20: tO02 7). aes 49 50.5 74.6 Oa 82.2 28 tO820.. ci een 50 43.0 73.8 68.2 80.0 ZO stORS Ts oe renee 5I S775 WTA 64.9 76.4 32 tos33s 52 eye ees 67.4 62.5 rane ZA StORS 5 Coe eerie 54 28.1 6227 60.9 67.9 ZOetOes 7
| Right | 5-2? | Richt | 5-D- 31. Finger clip....| .105 .625 9) 0) .075 .644 32. Ford timer rol- eR AG en hn Ba) .625 .068 .649 fe) fe) 33. Spring hinge ..|_ .158 .60 13 .63 .025 .696 34. Coin safe.....| .47 .508 sea soe Bods: Anpewretcn ..;.'.. .842 .40 56 Measurements of Mechanical A bility Some of these models were discarded for the reason that they are at the time improcurable. This was the case, as has been explained, with models No. 34 and No. 35. Of the other models some were found to involve too much mere physical strength, asin the case of the “finger’”’ paper clip and spring hinge. SECTION XIV RELIABILITY The self-correlation of a test is commonly utilized as a measure of its reliability. If the reliability of a test were perfect, any number of measurements of the same individuals taken with that test would yield precisely the same results. This never is the case with any measuring instrument yet devised. The reliability of various tests, however, varies greatly, and in order to interpret intelligently correlations obtained with a given test the reliability, or self-correlation, must be known. The self-correlation co- efficients obtained for these tests are as follows: Considering Series I and Series II, scored in the regular way (counting partial scores) for 369 cases, 7th and 8th grades, r=.59+.02. For 23 graduate university students, men and women, 7 between Series I and Series II =.75. For Series I alone, alternate models were correlated as follows: Models A-C-E and B-D-F were each considered as a test,—that is, the two halves of the test were intercorrelated. The co- efficients found are: SUE ASES NCTE PREITY A te Rove ala tiene sate aise agate ceed reo hs r= .68 20 cases, Ist year high school boys, 22.0465. 20s. r= .80 116 cases, 7th and 8th grade boys.................. 7=.7§ Pa S EA NOC PAUASIIIG AGasiats sciet ete seed o' vidi ate aie» ol oe r= .79 eeamtenel ese COLIN TRACE ICS woh cect oh Nv whesl fy Ai he r= .06 PMY eels OLIVET AUS MOVE ein ax ata Sorc ei Mapa ee itidiuile ere aed r=.45 It is probable from the above coefficients that the true reliability is between .6 and .7.. For two groups, the high school class and 7th and 8th grade boys, it runs up even higher. This degree of reliability is probably as high as can generally be obtained with such material, but it is not all that could be desired. It is to be hoped that further experimentation will result in scales of higher reliability. 57 SECTION XV CORRELATIONS The correlations of most interest are those with general in- telligence and with other available criteria of mechanical ability. I. CORRELATIONS WITH GENERAL INTELLIGENCE The most reliable of the former were obtained from the Army records, which between Army Alpha intelligence test and Series I are as follows: “Camp Taylor, 109 unselected men....................-. r= .323 Camp Devens, 107, foreign eliminated, but largely inferior PTT wei Mie Pet | | ae ead mE daa ace lnaat Mat nde ecb phe Aa alge r= .35 Camp Bee, 76cunselected: men, 0. aks fag eh aaa eee eee r= .30 Camp Lee, 30 men below 501in Army. e00 2005. .20. 2 r=.00 approx. Camp Lee, 216 men low grade, individually examined... .. r= .00 approx. Camp Dix, 909 men, 303d Engineers, unselected ......... r=.51 Massachusetts School Feeble Minded, 30 cases, with mental Sh RN os UGE MPs Ge or aici ated APE Otte ee ARAN ae ee OLE gen ame r= .32 Same group with officers’ ratings. .... r= .25 For 100 7th and 8th grade boys, New vor Puphe schasis! between Series I and composite intelligence score, made up of Haggerty, National 1 and 2, Otis, Kelley-Trabue, and OMY ELENA ane, cre arisen Tu oe hea fe teen Oy auth ge ote SER cheer t= .397 For same group, same tests, with Series IJ............... r= .338 2. CORRELATIONS WITH OTHER CRITERIA OF GENERAL MECHANICAL ABILITY The best available criteria of general mechanical ability of the kind supposedly measured by these tests has been manual training and science teachers’ ranks.’ It frequently is true, however, that these ranks are too unreliable to be trustworthy, because the pupils’ abilities are not well known to these shop instructors. An effort has therefore been made to obtain classes having two shop teachers, making it possiblé to intercorrelate the two rank- ings for reliability, before considering either of them as a criterion. The coefficients obtained are as follows: 58 A Description of the Tests SHOP TEACHER RANK AND SERIES [| 27, 7th and 8th grade boys in Lincoln School..................005: 15, 8th grade boys in New York City public schools.............. 24, 8th grade boys in New York City public schools.............. 14, 6th and 7th grade boys, Horace Mann School. ................ 18, 6th grade boys in Horace Mann School........ 17, 6th grade boys in Horace Mann School........ 59 r= .83 r= .80 r=.42 r= .81 r= .90 r= .88 ~\ SECTION XVI SUMMARY OF ASSEMBLING TESTS We have then as a result of-our experiments three instruments for measuring mechanical ability of the kind herein described. Two of these, Series I and Series II, are of practically equal dif- ficulty and can be used interchangeably for Grades 5, 6, 7, 8, high school and adults, generally. Series ea is much easier, iets adapted to Grades 3, 4, 5 and 6. | eeanentiiie a The norms given are admittedly based on a pons aie number of cases, but because of the method of scaling adopted these can be quickly and continuously substantiated or revised as more records become available. The correlations show that the reliability of any one of the tests is reasonably high as compared with other tests. More than one series now being available, this can be increased by retesting. The advantages in the method adopted in scaling are chiefly that scores are reported in well-defined terms—namely the variability of 12-year-old boys—and that the scores are directly comparable with T-Scale scores of other tests, as well. The short form of scoring permits the rapid testing of large numbers. As to what the test measures our correlations show that it selects ability markedly different from that discovered by verbal tests of general intelligence,—the correlations never ranging over .5, and for most groups being nearer .4. On the other hand, it does detect those qualities that cause a pupil to excel in the opinion of manual training and science teachers. Whatever this ability is, it is not, however, trade skill, any more than it is verbal intelli- gence. It is rather a composite of common sense and skill in managing physical objects of a mechanical nature. It might be called general mechanical intelligence and ability. The origin of this ability is not here considered, but its distribution is shown to be largely regardless of ordinary school classification. Ordinarily we are most interested in determining whether a pupil is unusual in this type of ability, and this the tests show us admirably. As for making hairbreadth distinctions between 60 A Description of the Tests 61 pupils because of slight differences in scores in these tests, caution must continually be counselled here, as well as in the use of other mental tests. We have in these tests, then, instruments for obtaining a definite measure of a trait which is generally estimated with great inaccuracy by school authorities as well as by parents and pupils themselves. The shortcomings of the tests have been repeatedly noted in this report. Their advantages and the uses which can be made of them are obvious. SECTION XVII MEASURING MECHANICAL APTITUDE BY MEANS OF ILLUSTRATIONS: - PIcTURE TESTS OF MECHANICAL APTITUDE ! I. AIM AND PURPOSE The natural limitation in any “ material test,’’ i.e., one requiring physical apparatus, is of course that such tests are somewhat difficult to administer in large school systems where thousands of individuals are to be tested. This is chiefly because the scoring . must be done after testing each class before the material can again be used. While a large number of outfits may be available, it is out of the question to have a set for each pupil as with paper tests, and it is therefore not possible to test large numbers in a short time, as can be done with paper tests. Moreover, physical ap- paratus, while of far more intrinsic interest to the pupils, is of course more cumbersome to handle than mere sheets of paper, and requires somewhat more mechanical skill in scoring and managing. To meet this increasing need for some means whereby a teacher or principal may quickly obtain some measure of the mechanical abilities of large numbers of pupils in great school systems such as, for example, in New York City, and in survey work generally, the writer set out to develop a series of paper tests of general me- chanical aptitude, and to evaluate these in terms of mechanical ability as shown by the assembling tests; by shop ability as shown by rank given by teachers of manual training, and in terms of general intelligence. These tests involve judgments of mechanical relationships and a general knowledge of things mechanical,—their principles, operation and use. While the actual trial at manipulating de- vices, such as in assembling tests, is sacrificed, many of the same general mental processes are called for. Because of the difficulty 1For samples see Stenquist Mechanical Aptitude Tests, published by World Book Co., Yonkers, N. Y. 62 A Description of the Tests 63 in obtaining suitable models for assembling tests, they are limited in range, but the moment the problem is transferred to paper an enormously larger range of applications is opened up. Thus, while it is impracticable to use the assembling of a lathe or engine as a test, it is quite as easy to treat such devices by means of pictures and questions as is a paper clip or mouse trap. If a paper test of mechanical aptitude, even partially as effective as the actual manipulative tests, could be invented to measure the same general trait, it was thought to be quite worth while because of the ease with which it can be utilized for large numbers. The need for something of this kind is particularly urgent in connection with vocational and educational guidance. Here, as in the assembling tests, the aim is to measure individ- ual differences in that certain general ‘‘ mechanical bent”’ or “‘ turn of mind” of children of school age,—well recognized by all, though but vaguely defined in the minds of most persons. The marked distinction between pupils in this kind of ability is, how- ever, well known to every parent, and to every teacher,—partic- ularly to teachers of any form of shop-work: but unfortunately, almost nothing has been done to obtain an exact measure of it. But this ability must not be confused with trade skill, or trade knowledge. The Army trade tests are better adapted to select skilled mechanics. This, however, is not the problem with boys of the upper grades and high school. The problem there is to discover differences in general mechanical interests and abilities which will constitute reasonably intelligent bases for guidance. 2. DESCRIPTION The technical names and language involved in mere verbal questions on mechanics,—including descriptions of mechanical devices and processes, defeat their usefulness as tests of general mechanical ability. Advantage was therefore taken of what is probably the best substitute for objects to actually handle— namely, illustrations of such objects. By means of these it is possible to present a great number of mechanical problems with the utmost ease, without the use of any language, and in addition, a large number of problems in non-technical language by simple questions referring to illustrations. The method of arranging the illustrations in such a way as to call for a judgment of relationship between two or more ideas has | 64 Measurements of Mechanical Ability previously been employed with marked success by psychologists in verbal and picture tests of general intelligence and other traits. By this method it is often possible with pictures to present a more pertinent and telling question than by technical, verbal descrip- tion,—and always more easily. The comparison of the mental processes involved in actually manipulating parts of mechanical devices, with those involved in answering the questions presented by the illustration tests, is best portrayed by the correlations shown in actual trial. This is treated statistically in a following section. Selection of Subject Matter. No test can do more than sample the almost endless variety of mechanical contrivances of man. In complexity, they range from the absurdly simple to the almost infinitely complex—from the stone axe of primitive man to a Mergenthal linotype, or a modern battleship. But generally speaking a few principles and laws of mechanics govern them all, and each new invention is for the most part but a novel combina- tion cf old principles for new purposes. The specific devices selected to be used as the basis of test questions may not therefore be of as great importance as seems apparent at first thought. In these tests a consistent effort has been made to select on the following bases: 1. Devices must be of general interest, and not pertain to very highly specialized trades. (Common household articles that are of a mechanical nature are most apt to fall within the experience of every one. 2. The question involved must be as mechanical as possible in its nature, involving a knowledge of, familiarity with, or understanding of the pur- pose, use, operation, construction, or reason for special size, shape, weight, material, etc., of the device in question. In the main the models chosen in these tests are common rather than highly specialized devices. No trade or occupation is singled out. But in cases where a somewhat special tool or device is included the question asked is of a general mechanical nature, that does not necessarily require acquaintance with that particu- lar device. While the present series are of a generalized nature, it is clear that a large number of series, each of which, while not strictly a trade test, would nevertheless deal with a restricted field, would be of great value. Thus, for example, there is need for a stand- A Description of the Tests 65 ardized test of carpentry, cabinetmaking, cement construction, blacksmithing, sheet metal working, etc., particularly in connec- tion with vocational education. The answering of the questions of these tests involves a certain type of information and ability in perceiving and judging mechan- ical objects and their characteristics that seems almost instinctive - in some individuals, and almost wholly absent in others. But what the psychological processes and principles involved are, is not within the province of this study to attempt to demonstrate. It may not, however, be out of place to point out that the mental thresholds between the type of mechanical ability herein treated— and other skills and information, particularly general intelligence and common sense—are not sharp, clear-cut lines. On the con- trary, these abilities probably merge imperceptibly into each other. _ Scoring:AntImproved Method: Brief mention may be made of the method of scoring, which has been so simplified that it can be done efficiently at high speed by clerical help. In addition to employing the ‘“‘key”’ method, a further expedient has been introduced in binding the pages with overlapping margins® By placing all the answers at the edge of the page they are exposed without the necessity of opening each page and repeatedly read- justing the stencil, which, though simple, is wasteful of time. Thus, while as much as five minutes is sometimes required in scoring such a booklet by the old method of opening each page and adjusting the stencil key each time to scattered answers,—by this method it can easily be reduced to from one to two minutes per booklet. Keys are so designed that only one adjustment is necessary. Ease of scoring, while always subordinate in importance to reliability and efficiency of the measuring power of a test, be- _ comes of great importance to the practical administrator of tests, and, in fact, in large school systems it becomes almost the sine qua non of a usable test. For, if scorable only by experts and at great expenditure of time, a test is practically worthless to school ad- ministrators who face the alternative of ‘‘ putting it over’’ through the machinery at hand,—the teaching and supervisory staff, or else foregoing it altogether. 1Excluded-in-first-edition. 66 Measurements of Mechanical Ability 3. PICTURE TESTS I AND II OF MECHANICAL INFORMATION AND APTITUDE A total of 173 questions, some expressed in terms of pictures to be compared one with another, and some in terms of printed queries referring to lettered pictures of machines and common mechanical articles were originally compiled into two tests, I and II. In Test I was placed only non-verbal material. In Test I the task is to determine which of five pictures “‘ belongs with, isa part of, or is used with”’ each of five other pictures. The total test has nineteen distinct group elements. The test is scored by counting the total number of items right. Test 2 is divided into ten parts, each consisting of from five to seventeen questions. The first of these consists of nineteen pictures of mechanical toys, and each of these pictures has been cut into two parts. The task is then to find the missing part for each picture. Parts 2, 3, 4 and 5 consist of a series of questions relating to the mechanical properties of each of four lettered pictures of typical machines: An ordinary electric bell, a blower, a countershaft, a power drill press. The questions asked are, however, answerable by competent persons, even though they have not had direct experience with these par- ticular machines, as they involve chiefly mechanical reasoning and perception. The last group of questions pertains to the construction and operation of two ordinary derricks. Here as in the other groups the ability to answer the questions does not depend so much upon a direct experience with such machines as upon insight into mechanical principles and usages. Scale Difficulty Values. After a few preliminary trials had showed that these tests correlated well with shop teachers’ ranks and with the assembling tests, 664 of Test I and 1087 of Test II were given to Grades 6, 7, 8 and high school. On the basis of these records the average relative difficulty of each element was computed. The results appear as Table XIII for Test I and Table XIV for Test II. T-Scale Values for Each Raw Score. The same method of scaling as employed in the assembling tests has been adopted for these tests. Tables XV and XVI give the T-Scale values for each number right for each test. These tables also give the age A Description of the Tests 67 distributions for other ages than the 12-year-olds, so that the percentage of any age which exceeds a given score can be seen at a glance. This is the same arrangement as in the case of the as- sembling tests. TABLE XIII PICTURE TEsT I* PERCENTAGE OF RIGHT ANSWERS TO EACH PROBLEM AND S.D. EQUIVALENTS To Eliminate Minus Signs Zero Is Considered as at —5 S.D. Grade 6 Grade 7 Grades Problem eo esse | Average S.D. Bos Per Cent Per Cent Per Cent Equivalent Right S.D Right S.D. Right S.D Lace kins A 621 47 .586 48. .675 45.5 46.8 Pe ee ere 3 fh 307 55 ¥235 iw fe .329 54.5 55.5 Pa ee ae 321 54.5 .288 Soa5 . 3890 53 54.3 Tak ORE dS .70 44.5 -534 49. .618 47 46.8 Le Ce rt 679 45.5 Te ABs .8II AI 43,0 —3 rc ees BS .362 es .316 56 ITA. 55 54.5 én eee .562 48.5 502 50. .50 50 49.5 OS ave cnke Paes 452 51 Sp 3 49.5 .508 50 BOs oN bat. detene Sm 30 55 274 56. 297 Wiss oy 55-5 CO Ee Oe 262 56.5 .214 58 B22 Bes Laplne. EL, sak Cos 286 56 .260 56.5 232 S75 56.6 ee ee See 421 52 386 533 472 51 52.0 1 Le ie ee a 242 SF, 379 is 3125 354 54. 54.8 CAP eats E252 560.5 . 309 She to2 Cee 55.0 | eit Alor .318 ite 393 53% 393 Sele 53.6 LO rane estiias .204 58. . 246 Cy be Sse Sse 56.6 4 EWN AR i ee . 238 577), .298 BSe5 . 3360 54.5 55.6 org eee aks .142 60.5 ie the S73 .193 58.5 58.8 Oe ce os ane 26 61.5 .214 58. .229 S75 59.0™ * One group of ten pictures to be matched is considered one problem. 68 Measurements of Mechanical Ability TABLE XIV Picture TEst II PERCENTAGE OF RIGHT ANSWERS TO EACH PROBLEM, AND S.D. EQUIVALENTS To Eliminate Minus Signs Zero Is Considered as at —5 S.D. EXERCISE I Grade 5 Grade 6 Grade 7 Grade 8 Prahienn n=168 Nn =314 nN =228 n =348 Per Cent} S.D.. |Per Cent] S.D. |Per Cent). S.D...|Per Cent; $.D. i BAN cosa thy Batt 215 443 742 435 885 380 880 382 A Aen Sein at 57 482 682 453 .837 402 He 425 eee AER Pee ec 44 515 534 AOI -610 472 600 474 OSE ER 358 521 433 527 .470 508 511 495 CRA Sein et eh Tes a 53 499 622 469 . 767 427 765 428 O Sih ntktame oirepars 328 545 423 519 500 500 558 485 Oita e eeeelctones 590 477 623 469 790 AIO 760 429 TO... ...-eeee 405 524 459 511 482 505 495 501 LE era wee atelsiecs 547 A488 602 474 710 444 799 416 ERS ces etches .505 499 .604 473 1759 430 782 422 A Se eI oa 2 .62 469 741 435 .825 407 .852 395 DAVE AES orc sine si 482 .642 463 As 434 772 425. Tic eee cree -46 510 -591 477 695 448 .719 442 LO a Bie sme § .50 500 .710 444 .729 439 -747 433 CT a oe .56 485 .699 448 . 730 437 .750 432 TS eek « pines .40 526 .470 501 -535 474 .578 480 TOR mere as eee .815 410 .853 395 .940 344 917 361 Average: 64 per cent right EXERCISE 2 Figure 1 1 ciate Sheen oh ePe\ .388 528 -461 510 .579 480 2735 437 2 shia fe tatenaianeede .008 629 121 617 pane S73 -354 537 Wit prten is! Mt, Ae -490 509 NIP} 412 .769 426 .802 415 ARE ieee 047 668 .092 639 Dey 614 .189 588 cere sank .ok te .316 548 .484 504 .543 480 .705 446 (ae Liabe want ALAR att +167 597 . 268 562 . 399 526 -445 514 foe nh OW eA OREN .035 682 Sy 3 Ws) 620 Sate 612 .216 579 Soren aac .057 658 .086 637 .158 600 233 573 Average: 37 per cent right Figure 2 Tiieieyewoaetess wate .442 520 -423 519 .570 482 -625 468 Pee 334 543 . 366 534 -519 495 -§25 494 Zalartetete eaters e . 238 571 .379 531 .430 518 605 473 Ae eat ge. .202 583 . 283 558 -399 526 495 501 SM tae -AII 522 -398 526 -456 ees .477 506 Ohare ci 8 ay3 594 -234 573 . 386 529 .460 510 PF el hina Va eee ees was: 583 .229 574 EP ee | 572 - 394 527 Average: 42 per cent right Figure 3 1 GEA, Paar PEE A .405 524 -553 486 698 448 .705 428 mB Sei NS ee aoe .220 577 .32I 546 -390 528 -422 520 Bie vavele mudeseces .460 511 .465 509 .580 480 .564 484 Atpe cis eateries .I61 5909 1252 567 -329 544 435 514 enh ae Greens eae .185 590. Sevag 546 EY) 573 .216 579 Average: 44 per cent right A Description of the Tests 69 TABLE XIV—(Cont'd) EXERCISE 2—(Cont'd) Figure 4 Grade 5 Grade 6 Grade 7 Grade 8 Problem a =168 mM =314 n=228 n =348 Per Cent}. S.D. |Per Cent} S.D, |Per Cent] S.D. {Per Cent!’ S.D: ey ae ok ee . 430 518 .6.40 404 .830 404 .875 385 «Ry ASS Ee 280 559 321 546 482 505 .511 497 UME sao ted 6 3 107 624 143 598 280 558 314 548 PS eae ee .053 662 ray 614 236 572 -330 544 Leia er eee eee .047 668 137 610 149 604 161 599 Re .035 682 .044 671 127 614 181 5901. 71 Be ee 214 579 277 559 .490 501 .482 505 RE 2 ahd aera ee 202 584 204 583 .390 528 322 546 erate whee ek 077 643 140 608 .241 570 293 505 Io. -340 541 .360 530 456 5II A451 512 i Ry Re ee ae .088 635 .146 605 219 578 i 593 Os ee ea a es IOI 628 ob ars 594 202 584 .187 5890 Average: 31 per cent right EXERCISE 3 Section A Sites ae Goes .452 Sire .547 488 .629 467 .652 461 As ee ty cee Wiena as .256 566 277 559 .500 500 EN he | 496 oreg e Beare epee .179 502 .158 600 324 546 .362 535 See yo ee fe ate. 548 . 286 557 -447 514 457 SII ie shee ae oe .250 566 . 261 564 .394 527 .402 525 a GH 3s Eten cp .244 570 -251 507 .486 504 394 527 RVG e et Seas eye ee 244 570 .267 562 -415 521 .385 529 POE e etd dcik . 262 564 .242 570 e507 496 -407 501 Thee a cet. e .208 581 .204 593 .405 524 2437 516 ONE tries ote .280 555 . 236 572 495 501 .500 500 bec thee a eee .328 545 .236 572 .552 487 uEas AOI Average: 38 per cent right Section B Dn etas Mec: kta .274 560 .341 541 .517 496 . 569 483 Phare ah ates. 325 545 -353 538 .430 518 434 516 ea eres Care eee .O4I 674 .124 616 .184 590 .218 578 Ae Soa ian SI TO 618 .242 570 .258 565 3322 546 SR farvaga: sve .234 570 .302 552 .469 508 .506 498 Average: 35 per cent right Section C 1 Ce SARE ML ah a eB 612 . 219 578 .302 552 .304 551 SE Rae Ee 185 590 .216 579 .280 559 aee5 566 = aS ee (220 545 Oy 582 .294 554 .282 558 Aer s, cto nha 5 bes .220 578 a ep 573 .368 534 .330 544 at cay) Weer es Se .O71 647 . 168 596 . 268 562 .290 550 ‘Oy 5 MSR a .244 570 Pale 549 .500 500 .422 520 1S. epee eee .202 584 242 570 .507 496 .442 575 Average: 31 per cent right Section D iE oe 9 RS ae O41 674 .O51 664 .224 576 {22 580 eee ee 5 ware .006 751 .O13 723 .023 700 £1 ere me <1 ae eer 5 O21 704 .005 758 Pye arn eye ees I3I 612 aad 514 2364 743 .328 545 Wi os eee I19 618 3222 By 461 510 .391 527 Average: 17 per cent right 70 Measurements of Mechanical Ability TABLE XV. SHOWING THE RAw ScorES (NUMBER RIGHT), T-SCORE EQuIv- ALENTS, AND THE PERCENTILE RANKS FOR EACH AGE CORRESPONDING EACH SCORE FOR TEST I Total Number Cases, 1130 Percentile Rank Percentile Rank Dae. 7 for each of five ages ely for each of five ages Score | Score Score | Score (Num-|Rquiv-| 11 12 13 14 rs ||{(Num-lequiv-| rr 12 13 14 15 ber | alent rs. rs. | yrs. rs. rs. ber | alent rs. rs. rs. rs. res Right) ‘ss Wy uP a fe Richt) a YE uA Ne 4s mos mos mos mos. } Mos mos mos mos mos. mos I 15 51 64 94] 9f | 84] 74] 69 2 16 3 65 95 92 85 76 71 3 17 53 66 96 93 87 78 738 4 18 54 66 07 | 94] 88 0s 5 19 I 55 67 98 | 95 | 89] 80] 76 6 20 I I 56 68 98 95 90 82 78 7 OT 2 I ie? 69 99 96 QI 83 79 8 22 2 I 58 70 09 07 92 84 80 9 23 2 2 59 70 99 | 97 ] 83 85 81 ae) 24 2) 2 I 60 71 98 94 86 82 Il 25 3 2 I 61 71 98 94 87 83 12 26 4 3 I 62 72 08 95 88 84 13 25 4 3 2 63 72 98 | 95 89 | 85 14 28 5 3 2 I 64 73 99 96 90 86 15 29 6 4 3 2 I 65 73 99 | 96 OI 7 16 30 7 4 3 2 : 66 74 O7 fF 92°) 83 2 31 8 5 3 3 2 67 74 07 | 92] 89 18 32 9 5 4 3 2 68 75 08 93 90 19 33 10 6 5 4 3 69 75 98 93 90 20 34 II 7 6 5 4 70 76 99 | 94] 9I 21 35 13 8 7 6 5 75 76 94 OI 22 36 uty ide) 8 7 6 72 TA 95 92 23 Sr 7 12 9 8 a Ts 77 95 92 24 38 19 14 10 9 8 74. 78 96 93 25 39 22 16 12 II 9 75 78 96 94 26 40 25 17 14 ite) ame) 76 79 97 94 27 41 28 19 16 14 LI 77 79 97 95 28 42 32 21 18 16 re 78 80 98 95 29 43 36 24 20 18 I5 79 80 98 96 30 44 40 27 23 20 17 80 81 99 96 31 45 43 31 26 23 19 8I 8I 97 Bo 46 47 35 29 2K 21 82 82 97 33 47 50 40 32 27 23 83 82 97 34 48 5401 45\) 935.) 20 14025 84 83 98 35 49 59 50 38 31 27 85 83 08 36 50 OFS Sac Aa SA a PesCt Eee 84 98 37 51 oad WR oa WORE oid Niet ey hale 7 84 98 28 52 70 62 50 42 39 88 85 98 39 53 73 66 55 46 42 89 85 99 40 54 76 70 59 50} 45 90 86 99 41 55 79 73 61 53 47 OI 86 99 42 56 81 75 63 55 50 92 87 99 43 57 83 a7 65 57 52 93 87 99 44 58 85 79 67 59 55 94 88 99 45 59 87 81 70 61 57 95 88 99 46 60 88 83 73 64 60 Median 47 61 90 85 76 66 62 ||Number Right} 33 35 38] 40 42 4 49 62 92 89 80 70 65 Median 50 63 93 | 90] 82] 72] 67 T-Score AT) maou 952"| Sas be A Description of the Tests 71 TABLE XVI. Raw Scores (NUMBER RIGHT), T-SCORE EQUIVALENTS, AND PERCENTILE RANKS FOR EACH SCORE FOR EACH AGE FOR TEsT II Total Number Cases, 1087 Percentile Rank Percentile Rank for each of six ages for each of six ages Raw T. Raw Ty Score | Score Score | Score Num- |kquiv-| ro | rz | r2 | 13 | 14 | x5 |{(Num-|equiv-] 10 | rz | 12 | 13 | 14 15 ber alent | yrs.} yrs.| yrs.| yrs. | yrs. | yrs. ber | alent | yrs.| yrs.| yrs. rs. | yrs. Right) si “4 vp 4 ve Right) ee re 4 y vp yrs. mos.}mos.|Mos.}/Mos.}Mos./MoOs, mos.;Mo0OSs.}MmoOs.}MoOs.}Mos.|mos, I 20 I 43 6r j95 |90 |83 {78 |75 {71 2 22 I 44 62 |06 jor |85 |80 |77 {74 3 24 I 45 62 |97 193 |87 |82 |79 |77 4 20 I 5 28 2 I 46 63 |97 |94 |88 {84 |82 [790 A7 64 198 |95 |90 |86 |84 {81 6 29 3 2 I 48 64 |99 |96 j9o2 |88 |86 183 7 30 4 2 3 I 49 65 [99.4197 |94 |90 |88 {85 8 31 5 3 2 I 59 66 199.9198 |o5 |o2 |90 |87 9 32 6 4 2 I 10 33 8 5 3 2 I I 51 67 99 |96 |94 |02 |890 52 68 99.2197 |95 |93 |90 II Te 4a6 th Os Al I I 53 69 99.4;97 |96 |94 |92 12 35 12 8 3 2 2 I 54 70 99.6198 |97 |95 |94 13 36 15 9 6 4 3 2 55 71 99.9199 |98 |96 95 14 36 18 | II 7 4 3 2 15 37 21 | 13 8 5 Ae 56 72 909.2108 |97 |96 57 73 99.4199 |98 197 16 37 PM) ws Bas De Oa a ad | 58 74 99.6]99.3}98 {98 17 38 27 | 18 | «1 8 6 5 59 75 99.9199.6198 {98 18 39 30 | 20 | 13 9 7 6 60 76 99.9199 |98 19 40 Sa e217 05 4 ato 8 8 20 40 36.|"a2 [16 5|or2 } 20 9 61 ae 99.1198 62 78 99 .3}98 21 4I 39 |726,, 18! era) 12") to 63 79 99.5|99 22 42 AZ Ne20. 4820) (STOR TA. | 102 64 80 99.7199 23 43 AO | F399) (027 Nels 110 Pod 65 81 99.9|99.I 24 44 SO jse (ces ae2h Wiroulveo 25 45 54 SOh 25 [a 2s 2001 ro 66 82 99.2 67 83 99.3 26 46 | 58 | 42] 31 | 26] 23 | 21 68 84 99.5 27 47 620) FAG esa e255) ez 23 69 85 99.7 28 48 65 | 50 | 38 | 30 | 28 | 26 70 86 99.9 29 48 | 68 | 54 | 42 | 34 | 31 | 29 30 49 | 71 | 58 | 46 | 37 | 34 | 32 71 87 72 87 31 50 | 74 | 62} 50] 40 | 37 | 35 73 88 32 5I | 76 | 65 | 54} 44 | 40 | 37 74 88 33 52 78 | 68 | 57 | 47 | 43 | 40 75 89 77 90 36 55 84 | 77 | 67 | 58 | 54] 50 78 90 37 pag AM Re I Ee CEN eo IN oy SOAS, | ee eeeceerreceere sn reves: emir arvana 6 alg aa 38 57 88 | 8x | 73 |. 65 | Oz | 56 Median 41 59 93 7179) 73 | 70 | 65 Median 42 60 94 | 88 | 81 | 75 | 72 | 68 T-Score 44] 48 | 50 |] 53 | 54 |55 72 Measurements of Mechanical Abthty Form of Distribution for Picture Tests I and II. In order to convey an idea of the form of distribution for Picture Tests I and II for Grades 6, 7, and 8, the following figures are included. It will be noted that all these distributions conform fairly closely to the normal probability form. There is no reason to suppose the irregularities are not due to chance. ns 809 Range 0-66 right out of a possible 77. Median 26.44 (46 T}. n = 667. Range 0-95 right out of a possible 78. liedian 26.76, or (55 T). Fic. 12. Picture Test I. Form of Fic. 13. Picture Test II. Form of Distribution for Grades 6, 7 and 8 Distribution for Grades 6, 7 and Combined. Combined. A Description of the Tests 73 A Ty (co) Grade 6. n= 183. Grade 7. n = 214. Grade 8B. n = 246, Range 0-52 Right Out Range 8-54 Right Out Range 6-64 Right Out of a Possible 78, of a Possible 78. of a Possible 78. Median 21.42 (43 17). Median 28,58 (56 T). Median 29.64 (57 T). Fic. 14. Picture Test I. Form of Distribution for Grades 6, 7 and 8 Individually. Grade 6. n= Se Grade 7. n= Grade 8. nF 312s =eace : © 0-54 Bint Out Range 4-64 Rena Out Range 0-66 Right Out of a Possible 77. of a Possible 77. of a Possible 77. Median 26.48 (46 T). Median 26.47 (55 T). Median 36.23 (55 T). Fic. 15. Picture Test II. Form of Distribution for Grades 6, 7 and 8 Individually. 4. RELIABILITY OF PICTURE TESTS Asa measure of reliability of Test I, the first half was correlated with the second half. For 103 cases in Grades 6, 7 and 8, r=.79. For Test II, 200 unselected cases from Grades 6, 7 and 8 give coefficients as follows: Between Exercise I and Exercise 2, r=.61. Between Exercise 2 and Exercise 3, r=.68. These coefficients of self-correlation are sufficiently high to be acceptable. In corre- lating the scores in either of these tests with other scores, this reliability measure must be considered. The effect of the un- reliability is to reduce correlations, and also to increase the ap- parent amount of overlapping of age or grade groups. The reliability of these tests compares favorably with that of others. 74 Measurements of Mechanical Ability 5. CORRELATIONS WITH ASSEMBLING TESTS AND WITH SHOP RANKS The correlations of chief interest in the case of the. picture tests are those with other criteria of mechanical ability. The best of these is the score in the assembling tests. Those computed are as follows: Test I witH ASSEMBLING TEST [| No. r 6th, 7th and 8th grade boys, Lincoln School. ........ a By, 85 8th grade boys, New York City public schools ..... 33 .59 8th grade boys, New York City public schools ..... 35 .88 6th grade boys, New York City public schools ..... 39 44 Test II with ASSEMBLING TEsT I 5th, 6th, 7th and 8th grade boys, Lincoln School... 50 Wy irs 7th grade boys, New York City public schools..... 69 .45 8th grade boys, New York City public schools... .. 30 .59 7th and 8th grade boys, Lincoln School........... 23 .82 The other criterion available is shop teachers’ ranks. The coefficients found are: Test I WITH SHoPp RANK .- No. r 7th and 8th grade boys, Lincoln School........... 27 .83 Highrschooltboyadallivears) incl. ser oe) ie one ee 53 Othiwancirth Grade DOVer ii. il ce Gas ee eae 51 Oth rade DOVS ouch oe neon imaen Peo ge st 18 .59 DEN Prager Doves. 2 wees ieee sole eoe. ye hate tee eee hat ae hy .59 Test II witH SHop RANK 7th and 8th grade boys, Lincoln School........... 27 .84 6th and 7th grade boys, New York public schools .. 14 .43 6th grade boys, New York public schools. ......... ‘Np .65 The intercorrelations of Tests I and II are also of interest. The coefficients found are: No. r 7th and 8th grade boys, Lincoln School........... 25 .88- 5th, 6th, 7th, and 8th grade boys, New York City public'schoolsi'2, wean. cae nee) te eta ene eae 220.) 41.00 It will be noted that the public schools’ ranks always correlate lower than the private school ranks. This undoubtedly indicates A Description of the Tests 75 that in the private schools where the classes are smaller their abilities are better known. We may accept the highest correla- tions as most nearly true, since all chance factors tend to reduce the correlation. 6. SUMMARY OF PICFURE TESTS OF MECHANICAL APTITUDE The foregoing facts indicate that in these tests we have two use- ful instruments for detecting an ability which seems to be closely correlated with the ability to score in the assembling tests, and with qualities which lead shop teachers to rank pupils high or low. Itis, therefore, entirely justifiable to assume in general that a high score in the picture tests is an indication of general mechan- ical aptitude. To obtain the best measure, both the assembling tests and the picture tests, are advisable. For preliminary classification, however, the picture tests alone may serve. The most obvious query that occurs in comparing the assembling tests and the picture tests is somewhat as follows: ‘“May a child not be expert with his fingers and be able to score high in working with actual materials and still have but little knowledge of the kind called for in the picture tests, or vice versa?”’ The answer is of course to be found in our correlations. These range as high as .88 between the Assembling Series and the Picture Tests, which means that there is a very marked tendency for these two traits to be found together. This is not equivalent to saying that the two kinds of tests measure exactly the same traits. The difference between the obtained correlation and perfect correlation is a measure of the extent to which one trait occurs without the other. The ease with which these picture tests can be given and scored will be the chief reason for substituting them for the assembling series. BAR THE NEED FOR A BROADER DEFINITION OF GENERAL INTELLIGENCE SECTION XVIII ILLUSTRIOUS SCHOOL FAILURES Cases in which illustrious (not to include ‘merely successful’’) men and women were, while in school, diagnosed as failures by their teachers have been often cited. Many of the men and women who later became world authorities in their fields, were called at best but mediocre. Linnaeous’ gymnasium teacher told his father that he was unfit for any profession. Yet this boy later was to revolutionize the science of botany.) Charles Darwin says in his autobiography that he ‘‘was considered by all his masters and by his father as a very ordinary boy, rather below the com- mon standard of intellect.’ Napoleon Bonaparte in the final examination at his military school stood forty-second in his class. We may well ask with Swift, ““Who were the forty-one above him?’’ Robert Fulton was called a dullard because his mind seemed filled with things outside of school. Priestly, the great chemist, had ‘‘an exceedingly imperfect education.’’ Pasteur “was not at all remarkable at school. Books and study had little attraction for him.’’ M. Pierre Curie, late professor of physics at the University of Paris, and co-discoverer with his wife of radium, ‘““was so stupid in school that his parents removed him and placed him under a private tutor.”’ Such a list as this could, if space permitted, be continued to great length. Many men who to-day are national or world figures, but who had a poor school record, could be cited. Granting that these cases constitute but a minority, and grant- ing also a certain tendency to exaggeration by biographers who love contrasts, these cases are still too numerous and important to be ignored. The fundamental fact remains that the abilities 1 Citations are from Swift: Mind in the Making, Chap. I. 76 Need for Broader Definition of General Intelligence a7 of many pupils are widely misjudged in school, and the abilities displayed either unperceived or misunderstood because of ar- rested development, poorly suited courses, stereotyped curricula, and general lack of sufficiently broad means for estimating ability. No claim is here made that all so-called low I.Q.’s are misjudged — only that many are. 0 el eg DeNoe, MN — SECTION XIX Tue LARGE PERCENTAGE OF “Low INTELLIGENCE” That a great majority of pupils who enter the first grade drop out even before the end of first year high school is well known. Strayer’s study of 318 cities, quoted by Terman, shows that of those who enter the first grade, on the average only 37 per cent enter first year high school, 25 per cent enter second year high school, 17 per cent enter third year high school and 14 per cent enter fourth year high school. Studies by Ayers and Thorndike also show the same general tendency. Terman says, “‘It is not uncommon for one-third to drop out without finishing the first year of high school.’’ Retardation and elimination figures from every city offer annually additional testimony of the same general facts in elementary as well as high school. Terman believes that ‘not all of this elimination is traceable to inferior mental ability, but that a large part is due to this cause there is no longer room for doubt.’’ With this general statement all will of course agree. The question, however, of just how much is due to actual lack of intelligence in its broadest sense, we do not know. Terman pre- sents much evidence to show that with the use of the general in- telligence tests pupils who have low intelligence and who will drop out can be largely discovered beforehand. But a situation in which over 80 per cent of the pupil population is eliminated before they reach their goal, is not greatly helped by the statement that most of the pupils who thus are eliminated haven’t the general intelligence to proceed further. Is it not rather an indictment both of the curricula, and of the tests which select largely on identical bases? Terman suggests the query, “Are high school standards too high?’’ We might alse ask are they too narrow? Or, in general, too far removed from the kinds of mental capacities of pupils? If such great numbers of the school population haven’t the kind ‘| of ability we call general intelligence, why call it general? Fortunately there now seems to be a tendency to scrutinize more closely the nature of the courses offered as well as the abilities of the pupils. 78 SECTION XX Wuat Is GENERAL INTELLIGENCE? Certain it is that the term general intelligence is sorely in need of definition, for by the average person, and even a large number of specialists in educational measurement, it is accepted at face value to mean just what it says. But is it not a loose use of terms that permits us to use the name ‘‘general”’ intelligence to designate mental traits which are painstakingly limited to the literary-academic tasks of our present intelligence tests? Are we not misleading when we say that he, and (in effect) only he has general intelligence, who with paper and pencil can effectively do such things as, for example, solve simple problems in arithmetic, state the opposites for each of a list of words, fill in a number of deleted sentences, arrange words in certain logical relationships, decide whether a given number or word is identical with another; or write the seventh letter of the alphabet, arrange a jumble of words to form meaningful sentences, make a cross that “‘shall be in the circle but not in the triangle or square; state which day comes before Sunday; or write whether a sentinel should be trust- worthy, whether alliteration is a form of pentameter, whether cessation of belligerency is ever desirable; or state “‘what one should do if it is raining when we start to school,” or repeat ‘we are having a fine time. We found a little mouse in the trap,”’ or repeat ‘‘3-I-7-5-9,’’ or give the greatest possible number of words in one minute which rhyme with ‘‘day,” or any combination of such tasks that may occupy the 30 to 45 minutes, given to an average present-day intelligence test? What sort of mentality has the individual who makes a low score in such tasks but who when he drops out of school has the ability to organize a gang that is all but indissolvable? Or who drops out of school and builds up a world-wide business on the identical ground where “‘ brighter’’ men have failed? Or who can wrest from a Robinson Crusoe situation a triumphant career? Or even he who can start a balking automobile abandoned by ““superior’’ persons—men of higher I.Q.’s? Or what shall we say 79 80 Measurements of Mechanical Ability for the lamented low intelligence of the New York boy who es- caped from an institution for mental defectives and who before the authorities recaptured him had obtained and was holding a job paying him thirty-seven do'lars per week? To say that there are but few such cases is untrue, for even though the illustrious cases do constitute but a small minority, who shall estimate how many more of that large percentage who drop out of school, because it is unsuited to their needs, would develop into careers of marked usefulness, if their real abilities were discovered? | To say that such persons as those cited (except, perhaps, such ' cases as the last mentioned) are not possessed of general intelli- -gence is to quarrel with words. Though they may classify as “low I.Q.’s”’ by present-day intelligence tests, surely we are on _ uncertain ground if we take such results at face value and consider their cases closed. It is a question of what our tests measure, a question of what we mean to include under the term general intelligence. If we examine the type of criteria by which nearly all these tests are justified, we find that these consist in the last analysis essen- tially of teachers’ estimates of pupils’ ability in school, plus rec- ords in other academic tests. But our major contention is pre- cisely that for many children the teachers’ estimates and their academic record is merely an estimate of success in bookish tasks, and here it is that fallacies of intelligence ratings creep in. It is submitted that these intelligence tests, at best, detect only those academic qualities of pupils which are noted by teachers, and which, it is freely granted, are of great importance for success in ordinary school curricula, but which do not constitute the whole of general intelligence. Of this our abler investigators! are fully aware, but the average giver of tests is not aware of it,—or, if so,—overlooks it. npr: 1See Thorndike: ‘‘Tests of Intelligence, Reliability, Significance, etc.,’’ School and Society, Vol. IX, Feb. 15, 1919, and Henmon, ‘‘ Measurement of Intelligence,” tbid., Vol. XIII, Feb. 5, 1921. SECTION XXI OTHER KINDS OF INTELLIGENCE As a matter of fact, it seems clear that intelligence may be classified as of many kinds. Thus, for example, the campaign manager exhibits a quality differing sharply from that of the locomotive engineer; while the kind of intelligence required to lay out the construction work of a Woolworth Building is not very like that needed to write a forceful letter, and this in turn is not very like that employed in painting a great picture, inventing a great engine—or modern linotype. While it may be true that a certain minimum body of “‘sense,”’ mental agility, and some general academic information underlies all such activities, we know from at least a few correlations obtained (one of which appears later) that the relationship is not very close—though it is, to be sure, positive. If we had trustworthy criteria of ability in social leadership and in the various political and mechanical arts and sciences, it might be possible to devise intelligence tests that would be more nearly ‘““general’’ than those we now have. This, however, is a more difficult matter than to devise tests of academic ability. Again, while to measure in this wide sense the present ability of our school population represents a heavy task,—to prognosticate its potential ability would truly be a Herculean undertaking. But this is not equivalent to saying that it can’t be done. Much of the same methodology and technique which we already have would probably apply, and progress in this direction may be locked for. Current literature is already sprinkled with dis- cussions of the limitations of what our present so-called general intelligence tests measure. While unfortunately much of the criticism of intelligence tests emanates from self-appointed critics, incompetent for the most part to pass scientifically upon their merits or shortcomings, the best authorities, and many of the authors of the tests themselves, are well aware that more comprehensive and more valid instruments are urgently needed. “Compared to what we should like to have they are very faulty. Compared to what they replace, however, they may be notably superior.” 8I SECTION XXII GENERAL INTELLIGENCE AND MECHANICAL ABILITY The tests of mechanical ability herein described may serve as an example and case in point, showing a type of intelligence and also emphasizing the need for clearer definition of just what we mean when we say a child has but little general intelligence. During 1919-20 several hundred boys in a New York City public school (P. S. 64, Manhattan) were given a very exhaustive intelligence rating by means of the combined results in the follow- ing well known tests.! I. THE INTELLIGENCE TESTS The intelligence tests used in the study were: 1. National Intelligence Test A National Intelligence Test B Haggerty Intelligence Test Delta 2 Otis Intelligence Test . Meyers Mental Measure . Thorndike Visual Vocabulary Scale AAP ws The results of these six tests were pooled, giving equal weight to each, and the final rating called the composite intelligence score. These boys were next given a series of mechanical tests, consisting of the following. 2. THE MECHANICAL TESTS The mechanical tests used in the study were: 1. Assembling Series 1 2. Assembling Series 2 3. Picture Test I 4. Picture Test II The detailed nature of each of these mechanical tests has been previously given. 1 For full report see Stenquist (J. L.), ‘‘ Better Grading through Standard Mental Tests,” Bureau of Reference, Research and Statistics Bulletin, 1921. 82 Need for Broader Definition of General Intelligence 83 If we now compare the results in the two types of examination we may observe the following points for this group. In the correlation between the Assembling Test, Series I, and COMPOSITE SCORE IN 6 INTELLIGEKCE TESTS bik TPT SD a ad Rd —fe{_[sol foe Tae Foe ce UY YY A a | EO 0 1 GEC wal YE A eS fg b2y 7a B E A ts iG. 16 i A a be ba The correlation between vi : fo ane | General Intelligence and General 72) Mechanical Ability (2 Assembling BE| Oye | ied able: | ae fal Tests and 2 Picture Tests) eer ~ Ei ole 7a ed Sd BS bbs jl SM ese OB a AW ec | fel [el [eo] e/*el%| | eal [| ie) 20 ox cases | | ele [%) [11 A ot ctees go [| eel TT TTT | felefofef el dele e] [oP ey TT Ey OD a a WW om NS Cee ~ ; De A a ott Stet fear eee Pt tt fet fet ete) toe | [Pees avestice®| | ot el | | lel el oles) ele! LT] oles) of [el | | | | [| felt] | [Pelosi %o| oho! g%| [el%i ei |) | F519 DE oS iam sei Pie rely spride fel Pal 1 (rere (oi) 2 Sol i SG WF oc pageeeeet SECCUGaans ene oo [TUE V OF ESE A iH Rime amimatsletieli esha De ees ee sae LI le ee | (PS BR FS A AH the composite intelligence score, r= .230 + .04 for 267 7th and 8th grade boys (Fig. 17). Between Assembling Test, Series II, and the composite intelligence score, r = .338 =.06 for 100 7th and 8th grade boys. Between Picture Test I and the same intelligence 84 Measurements of Mechanical Abthty rating, 7=.52+.07 for 50 6th, 7th and 8th grade boys. Between Picture Test II and the same intelligence rating, 7=.64 + .06 for 520 6th, 7th and 8th grade boys. (See Fig. 18.) ee ee are ee elo FA) bMS ole ke, The correlation between ‘General Intelligence and Mech- anical Assembling Test, Series s i eR ee BOHEME EEE EEE EEEE EERE BP Da SLL ABLETON PE Oe: If we now combine all of the four mechanical tests into one average T-score, and correlate it with the same intelligence rating, we find 7 drops to .21+.07 for 275 7th and 8th grade boys. (See Fig. 16.) The important inference to draw from these results is not with Need for Broader Definition of General Intelligence 85 regard to the exact coefficients obtained, but with regard to the general fact of low correlation between the two kinds of ability here represented. Results obtained in the Army for over 14,000 COMPOSITE SCORE IN 6 INTELLIGENCE TESTS Tee] Te] Jed Tool [so] [oe] [se] [56] fo] [aol [oe] CARRE oe a al a ad rte ey Ne 58 The aaa 8 between ied i i fall (D) 287% BA Sd) F General Intelligence and Picture | § | | | | Kar) c ptitude. ae Seas ai iene of (7 ame ath erate tors) TTT P| Tel |_ 1 [Palo fr TN 2 HH aleetaa Cid) (SS SSS Cie apes COSRS S088 0588 See [mle lsaletiaisutehe ele td lecle lt lel | lal aia lel 1 [tele leiele lel fafa lsat le le CCR PRPerpaeceepeet : Plet 11 Pele (| = Spaten hace eaveeetccntaee eaueorare Average PS = Vol | [Palle le ls Poclel%s4’ to ltl 1% 1%1 lelel 111 Lm 40) Cie RL Rss Rere Rite le eC a” Risin lmmeieleis eleleh. lf ate Wied feria [alate erations Petes lel ell Lael et halel forsee leet tofelel Sad leases! et te TT ee el aallalePerelcle ls ele meet Pet Lay lobe NSD ISIAS Gees see SSCL 2OE Sat FIP en latmapnhe Ps anbane [| pal fend marea ean gees bat a fal zeto = (| Je fa] a F170 joa NA nC Feral nw AAT lan. vam | ie akan fan ola elon [alana dee Aida [ ol cdot Iaae men bear out the same general fact.! An individual’s position in General Intelligence is thus shown to be largely independent of his position in General Mechanical Ability and Aptitude. 1 See page 58. 86 Measurements of Mechanical Ability Analysis of Total Distribution. Examination of Fig. 16, which " for convenience has been divided into quadrants each lettered, showing per cent of pupils included, shows that of the total cases, all in Groups A and C are below average in general intel- ligence, but all in Group C, or 20 per cent, are above average ability in the mechanical tests. All the pupils in both Groups C and D, or 46 per cent, are above average in mechanical ability. Of these 26 per cent are also above in general intelligence. But for the mechanical tests showing their marked ability in this direction also, it is unlikely that many of Group D would be en- couraged to look toward careers in mechanical fields, since they have marked abstract intelligence. Conversely, those in Group B would not be known to be deficient in mechanical ability, though above average in intelligence. Considering mechanical ability alone we may say that Groups C and D would likely succeed in this direction, while Groups A and B would not be likely to do so. Again, if we were to rely merely on the intelligence tests all in Group C would fail to be recognized as having ability, although 55 pupils, or 20 per cent, have ability of the other kind. Consider next Group A, who are low in both tests: It is not without value to have this double negative information. At least advice can be given less blindly than without such information. Again, there may be quite different types of abilities in which some of these may excel. Having them segregated we can proceed more in- telligently than otherwise, to say the least. Less progress should be looked for, for one thing. In short, the mechanical tests have given us important clues as to abilities which would not be revealed by the abstract intelli- gence tests alone. Though the correlation is positive it is so low as to permit wide differences in deviation. These are the measure of abilities untouched by so-called general intelligence tests. The Trustworthiness of the Measurements. As regards the reliability of our measure of general intelligence: Comprised as it is of six excellent tests, say one of which would generally be ac- cepted as a measure of general intelligence, constitutes an unim- peachable estimate of that type of ability which we now call general intelligence. In mechanical ability we have repeated tests of each of two types of mechanical tasks,—the assembling tests involving skill, and the picture tests involving mechanical Need for Broader Definition of General Intelligence 87 information and reasoning, i.e., we have in fact four distinct measurements of each pupil. The reliability of our measures is, therefore, acceptable, and much better than is generally obtainable. The Validity of the Measurements. The validity of a test deals with the question of what it is that it measures,—i.e., with correlations with criteria. The question of what the intelligence tests measure has already been dealt with in Section XX. As to what the mechanical tests measure we may cite the correlations which have been found in comparing mechanical test scores with pupils’ rank in shop courses, or in general science courses, as given on pages 59 and 74. These correlations are all subject to chance errors which reduce them. The true correlations are therefore higher,—probably .7 or higher. Shop teachers’ ranks are of course no better than regular teach- ers’ ranks which have been attacked in a previous section. But there is every reason to believe them equally good. Were other and better criteria available these would be excluded. In several of the above instances, however, only the average rank given by two shop teachers (intercorrelating .88 or better) were used. The mechanical tests may, therefore, be judged from these figures to detect to a marked degree the same qualities in pupils that are considered by shop and science teachers in judging pupils’ relative abilities. The second way of deciding what these mechanical tests measure is the very direct one of merely looking at the tests and judging what type of task it is that has been set up. Thus we may note at once that they represent an attempt (in all except Picture Test II) to get away from words. They deal with con- crete and real things, as against description of things. In the case of the Assembling Test it gives opportunity to do with hands and mind, rather than to perform with a pencil only, or to juggle mental abstractions. It may be thought, however, that the mixture of abilities revealed by combining picture and assembling tests is less il- luminating than would be either taken alone. To observe this point the records in one assembling test were plotted separately. These appear in Fig. 17. Strangely enough, the percentages in each quadrant is practically identical, with the correlation co- 7 88 Measurements of Mechanical Ability efficient .23 as compared with .21 in the former case. The form of distribution is very similar. The same interpretations may, therefore, be made whether we employ Fig. 16 or Fig. 17. In the same way the results of Picture Test II were plotted in Fig. 18. Here the higher correlation is apparent. The two tests are measuring more nearly the same kind of ability. SECTION XXIII THE RELATIVE IMPORTANCE OF THESE Two KINDS OF ABILITY Of the relative importance of each of these two types of ability readers must form their own conclusions. But it should be kept in mind that we are living in a world that is dominated on every hand by every form of mechanical device and machine. Every moment of present-day life is influenced directly or in- directly by the products of mechanical skill and genius. Is it not important that ability in this field should be discovered and developed? Rather than merely to dismiss our apparently stupid pupils as low in what we now call general intelligence, and to rele- gate them to some convenient class, might not our time profitably be spent in disclosing other kinds of intelligence of which they may be possessed ? The question of ‘‘what knowledge is of most worth”’ will probably never be finally answered to the satisfaction of all. But it seems certain that as life becomes more and more complex, the world’s tasks become more varied, and group inter-dependence increases, there is constant need for broader conceptions of what constitutes worth-while mental ability. We should recall that the history of the past century, as has often been said, could well be written in terms of the achievement of applied science and ap- plied mechanical genius. Inventions of hitherto undreamed of significance, which have revolutionized or at least profoundly in- fluenced the life of every nation on the globe, have sprung from this field of knowledge. And while the attempts to measure the mental abilities back of these forces, which are herein described, represent but crude beginnings, the importance of the task ts stoutly maintained. Indeed, to explore, measure and adequately capitalize these capacities seems at least as important as doing the same for the more abstract type intelligence required in academic school subjects. The discovery of special abilities has a two- fold significance and like the quality of mercy “‘is twice blessed”’: It not only opens the door of new promise to pupils, many of whom have been labelled as failures, but in doing so it leads toward further contributions to society. 89 SECTION XXIV FICTITIOUS STIGMAS There is a more or less universal notion that a low score in such tasks as have here been called intelligence tests constitutes a dis- grace that must be shunned at all costs. To fail to receive a high rating in intelligence is most deplorable—a great calamity. This feeling has come about partly through the loose use of the term general intelligence, and partly through distorted estimate of the role of intelligence in human conduct. But, absurd as it may seem, there is a brief, and a reasonable one, which can be held for the pupil with an actual low I.Q. as well as for the one with a supposed low I.Q. For just as in man we find enormous individ- ual differences in intelligence, so (fortunately) in the work of the world we find equally great variation in the character of the various tasks. As a matter of fact, the outstanding industrial tendency of the past decade has been to reduce the number of skilled jobs and increase the number of unskilled ones. The constant tendency of our modern machine age is in this direction, be it right or wrong. Again, consider the hundreds of thousands of menial tasks outside of industry that somebody in every society must perform. Is it not clear that happiness, contentment and efficiency in such jobs are far more apt to come with a low I.Q. than with one that is high? Indeed, even when we consider the world’s sweetest and most lovable characters, it is not always their high general abstract intelligence that makes the strongest appeal. Haven’t we in the academic atmosphere of our school rooms come to value the intellectual side of human nature out of proportion to its real significance in life? Surely far worse calamities can befall the human animal than that being pro- nounced as of low intelligence. Physical disease, a crippled body, an insane or actually feeble mind, with the multitude of tragic afflictions which this may imply—these and many other lament- able conditions which may befall should be kept in the background of our mind when we feel inclined to bemoan the lot of the stupid individual. go SECTION XXV SUMMARY OF Part II Part II attempts to point out some of the fallacies that are prevalent in the present-day considerations of mental tests. It recalls the many cases of illustrious men who were called school failures, and calls attention to the large percentages of pupils who at present appear to lack sufficient mentality to carry on current curricula, and suggests the query, ‘“‘Is it the curricula or the mental ability of the population that is at fault?’’ It criticizes present-day intelligence tests as narrow and academic in scope, being based largely on school success, shows the loose use to which the term “ general intelligence” is often put, and maintains that there are in fact very likely many other kinds of intelligence than that measured by the tests given that name. Asan illustra- tion the results of a study of mechanical ability are offered. Here it is shown that at least 40 per cent of the pupils from a typical school, who are below average in general abstract intelligence, are above average in the kind of ability required in four mechanical tests, the detailed nature of which is described. It is submitted that such ability may be of quite as general importance as that required to score high in the abstract general intelligence tests, in view of the fact that present environment is so largely permeated with the fruits of mechanical genius and applied science. Finally, it is maintained that there is a strong, but wrong tendency to at- tach a stigma to pupils scoring low in these so-called general intelligence tests. Even for those pupils whose true general intelligence is found actually low,—after adequate tests (many being only apparently low)—even for these ample ground exists for hopes of a useful and happy life doing tasks for which they are, in fact, better adapted than are individuals of high intelligence. Attention is called to the fact that just as we find very great individual differences in the abilities of human beings, so we find (fortunately) very wide variation in the types of the world’s work which is to be done; and that if the kind and degree of abilities possessed by an individual are discovered and properly capitalized, it should be possible to find appropriate opportu- nities for every one. APPENDIX ASSEMBLING TESTS 1. DIRECTIONS FOR GIVING AND SCORING 1. (2) GENERAL MANAGEMENT: Boxes are always handled in strap carriers; bundles of 8 or 10 can easily be moved about. Caution pupils to be careful not to drop boxes or parts. Ifa part should be lost from a box, place a protruding slip of paper in the compart- ment from which it is missing. Such box can then be identified instantly, and repaired later. Series I yellow tags; Series II green tags. (b) To Give TEstT: Use regular classroom, and single desks, if possible. With pupils seated, and 40 to 50 boxes, and also score sheets, near the examiner’s desk, proceed as follows: 1. Distribute score sheets, one for each pupil. (Make sure you have the right ones.) Each pupil fills out score sheet blanks—name, age, etc.—and leaves blank on his desk to be enclosed in the box when he finishes. (If he fails to enclose it there is no way of identifying his box.) 2. Appoint one boy for each row to distribute boxes to each row. Do not permit the boxes to be opened until all begin. 3. When each pupil has his box instruct as follows: ‘‘We will now read the directions; you read them, but not aloud. (Examiner now takes one box and reads the directions on box aloud, while the pupils read silently.) As soon as examiner has finished, and all understand, he says, ‘‘ You have 30 minutes; all ready, begin.”’ Note that boxes open backward. See that all get started right, beginning with Model A, B, etc. After about 3 minutes say again, ‘‘Do not spend more than about 3 minutes on any one model.’”’ Examiner should write down the time of beginning, being careful to allow just 30 minutes. 4. When time is up, each pupil-hands in his box (with record sheet inside). Stack the boxes immediately beside the scorer’s desk if they are to be scored at once, (c) FINISHING BEFORE 30 MINUTES ARE UP: A few extra-skilled pupils will finish before 30 minutes have elapsed. Have them mark the time spent on their record sheet, and allow each such record one-half point for each minute remaining up to 30—e.g., 22 minutes spent plus 8/2, that is, 4 would be added to the score. 92 Appendix 93 (d) SCORING: Select two or three pupils, who appeared to be doing the best in the test, as assistants. With boxes conveniently stacked beside his desk examiner-scorer proceeds as follows: 1. Sit down at desk. Take one box, open (cover toward you). Unfold Record Sheet. Now inspect Model A, and write score on Record Sheet. Inspect Model B, and write score on Record Sheet. Do the same for all models. When you have entered a score for each model, pass the box to your first as- sistant, who takes each model apart, being very careful that no parts are miss- ing, and that no model is overlooked. (The examiner will need to instruct his assistants once or twice for each model, after which they can disassemble models quite as wellashecan. But the examiner must continually emphasize the im- portance of extremely accurate inspectton—to see that all parts and all models are O. K.) 2. Proceed in the same way with all the boxes. After a little practice this process can be done at high speed, so that a whole class can be scored in a few minutes. To save lost motion the assistants stack the boxes directly on the strap carriers, when they finish disassembling. Thus one bundle (of 10) after another is finished, and strapped up ready for use again. Note: After the boy assistants have become very expert, it is permissible to train a very few of them to do the actual inspecting, that is, to actually enter the scores, on the record sheets, as official scorers. This must, however, be closely controlled by the teacher in charge, who will be responsible. 2. DETAILS OF GIVING PARTIAL SCORES In the standard score sheets for each of Series I, II, and III, the partial score values for various degrees of perfection in each model are listed as plus or minus values, which are simply points above o (every model is graded 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10) or below 10. Minus values are used because it is often more clear to ‘‘deduct”’ for a certain mistake than to ‘‘credit”’ for the partial solution. A sample record is shown on page 98. While these partial score values appear troublesome at first glance, they are quickly memorized, and after practice with a class or two, it may not be necessary even to consult the list of values. Occasionally new combinations of parts of models appear, which are not listed. These need give the scorer no great concern. He should assign what seems (in terms of the other partial values) a reasonable score value. The justification for this is that these small variations in partial scores affect but slightly the final score, because of the method of scoring. When each model has been given an individual raw score add these up, look up the equivalent T-Scale score in the proper table! and enter this T-Scale score in proper place under ‘‘Final Score.”’ This can all be done very rapidly with a little practice and with assistance as suggested under “‘ Directions for Giving and Scoring,”’ above. 1 Pages 95 or 98. 94. Measurements of Mechanical A bility 3. THE SHORT FORM METHOD—SCORING NUMBER RIGHT ONLY For many purposes it will be found entirely adequate to disregard partial scores and to count only the models solved perfectly. A large number of corre- lations between the two methods of scoring results in an average coefficient of between .8 and .9. A good plan when practicable is to give both Series I and Series II, when scoring by the number right method. This gives a more reli- able sampling, and minimizes the work of scoring. In utilizing this method of scoring all values of 8 and 9 as well as 10 are counted as right. 4. RAW SCORES AND FINAL T-SCORES The total number right (including the total of all partial score values, if the partial score method of scoring which is the more reliable, is used) plus any time credit which may be due, isthe raw score. For each raw score the final T-Scale _ score appears in the table. This should be entered as pointed out above as the final score. The T-Scale scores are the mean square Deviation Equivalents for the distribution of 12-year-old boys, as has been explained on page 43. Tables I and II not only give the T-Score values, but also the age distributions for several ages, making possible an adequate definition of what a certain T-Score means, 5. NORMS The median scores for each age constitute the Norms, for the maximum of scores available at time of this publication (February 1921).! 6. FURTHER DETAILS OF SCORING, AND HOW TO INTERPRET WHAT THE SCORES MEAN On the opposite page appears a sample Standard Score Sheet for Series I. Each pupil to be tested first fills in the heading on one such blank, and when he has completed his work with the box, the score sheet is folded lengthwise and placed inside the box for identification. When scoring the examiner then writes 10 under ‘‘individual raw score”’ for each model properly assembled, and whatever partial score (from 1 to 9) for models only partially assembled. INTERPRETATION OF A SAMPLE SCORE Suppose the record for John Brown, who is 12 years old, to be as follows: Raw Score Model'A; (perect) sige 2-2 te eum eect ee ee aL Model Bist pertect) une june cas Ge eee eet Model C, oR topes ote Ma coins MT ae eae Model D, freriect) af eta He ag ty ee 10 Models ch ee ears, th Se aia Te Te 4 Modelub Soni adit hvac enn oy tenes eBay ) Model fy uiie yates Maieih oO seed i Unene mi seas: ) Model pees a oneen ct er kun area O Mole] Feito afc chau ona ata meme teea ve cout O Models] 3 a0 A ih Og ces ba tig pra ene re iti a i ) Ota aa) as Coe ae AL a ven At etal ag 42 Tame: Bonuses eee aces eet er vee ce ) ‘Total Rawipcone eis dy ce een dee eee 42 1 See pages 45-46. Appendix 95 By consulting the table! the T-Score is found to be 56. Referring now to Table IX we find the following facts: A T-Score of 56 is equalled or exceeded by only 20.8 per cent of 12-year-old boys; by only 43.2 per cent of 13-year old boys; by 46.8 per cent of 14-year-olds, and by 75 per cent of adult men in the Army. We may also note the medians for each age at the foot of Table IX. These show that our score of 56 is exactly equal to the 14-year-old median. This gives us a well-defined notion of what it means. It shows just where John Brown stands in relation to boys of his own age as well as to those much older than he is. The same interpretation may of course be made for any score in any of the Series. Any standard of performance can also be set up for any special purpose. Thus for example it may be desired to select for certain reasons all pupils who score higher than 75 per cent of 12-year-olds in general,”’ or ‘‘all who score lower than 50 per cent of 13-year-olds in general,”’ etc. 7. DO. BESUSED AS: A) GROUP: TEST Each series is designed to be used as a class test, it being more practicable to test an entire class than a single pupil. In order to facilitate this the outfits have all been made up in one standard size. The uniform boxes are easily handled by means of special strap carriers, eight or ten such outfits when strapped up being not materially more difficult to handle than an ordinary suitcase. The outfits can of course be used over and over again. Full directions are printed on each box. These are read aloud by the exam- iner and silently by the pupils. At first thought it may appear that the expense involved is too great to use these tests as group tests. But it should be remembered the expense of time necessary in individual testing zs far greater than the cost of apparatus, not to mention the general impracticability of the method, in public schools. It should also be kept in mind that sets of 40 to 50 of these tests, for testing entire classes can be used continuously, and should be considered as permanent equipment. If the mental measurement of children is worth obtaining it is worth providing the necessary materials, for great pains have been taken in devising these tests to make them essentially group tests. In the Army entire companies were tested at once. 1 At margin of standard score sheet. 96 Measurements of Mechanical Ability SAMPLE SCORE SHEET SERIES I a (a TRA ae Soe Abe res ol (Ae i ore oles as ah, alah ie ah mead Saye ny AE NSE Oak ea se Oats eter (Nearest Birthday) RaTAC@ sc cause ee tem ia cee tee School: Uae ross soee wichle meine ae STANDARD SCORE SHEET AL EST T-SCORE STENQUIST ASSEMBLING TES | | SERIES I Individual NOTE: Do not fail to place this record inside box when you sro. have finished the test. FOLD LENGTHWISE. . Raw « ah ” . Model A Score Score Cupboard Catch. Spring wrong=—5; Knob wrong=—5; Bolt oto I 24 wrong = —5. 2to 3 30 Sait LOM Smet Model B 6 tO7 “a Clothes Pin. Spring properly placed on 1 stick =+2. Spring placed OO Olas at end of one or both sticks = +2. Io to Ir 38 ¥2/to.13) 40 Model C sr tO 15) "42 Paper Clip (Hunt). 1 lever properly in slot, but reversed =+2. Both +8 i . levers properly in slot, but reversed =+8. Both levers backward in 20 to 21 45 slot =-+2. All other combinations =o. 22 to 23 46 24 to 25 47 Chain. For each pair of links properly joined, +2; any number of 28to29 49 links only half (singly) joined, +2; All other combinations =o. 30 to 3I 50 32 to 33. ‘51 | Model E Sei tosdg as Bicycle Bell. Thumb lever on pin, reversed = +1; Correct = +2. ae to 37 53 Gear on pin, reversed = +1; correct =+2. Knocker on pin, inverted Aa ay ae ze =-+1; correct=+2. Spring hooked properly = +4. 42 to 43 56 44t0 45 57 Model F 46 to 47 §8 Rubber Hose Shut-Off. Thumb lever above spring backward=+8; 48to49 59 Thumb lever inserted under spring, any position = +2. 50 to 51 60 Model G §4,tO S50 Gr Wire Bottle Stopper. Rubber stop in place=+1. The two heavy 56to 57 62 wires properly connected =+4. Small wire properly connected=+5. 58to59 62 on N s ° mn w a ° 60 to 61 63 Model H 62 to 63 64 é : 3 64 to 65 64 Push Button. Button right=-+1. Button disk upside down, all else 66 to 67 «65 O. K.=+4. All O. K. except not snapped = +6. 68 to 69 666 Model I icin Lock. Lug in place=+4; Bolt in place=+1. Spring in place=+4. 74to75 68 Cover in place with screw = +1. 76to 77 69 78 to 79 70 Model J 80to 8I 72 Mouse Trap. All right except one spring = +7; Both springs wrong, 82 to s a4 otherwise right = +4; Only loop-lever, pin, and bait-trigger right =+2; 84t085 74 Only 1 et i i = fe 86 to 87. 75 nly loop-lever and pin right = +1 88 to 89 75 90 to9I 79 TIMER BONUSE ae ee NOTE TO SCORER: Score all perfectly 92 to 93 «80 LODAL assembled models 10. ‘‘—’’ means deduct 94 to 95 80 ‘ ” 96 to 97 81 RAW ies ORE Aparna a se from 10. ‘‘+’’ means add to zero. 98 to99 81 100 to 82 A ppendix 97 SAMPLE SCORE SHEET SeErigs II hb t.e 6 Seo Oe 8 44 8 Be 66'S sh ED DS Ce ble a. 8 he 8 48 © «Ole w Ce 6 a eS STANDARD SCORE SHEET STENQUIST ASSEMBLING TEST WARIS SERIES II Tt ' SCORE: | | NOTE: Do not fail to place this record inside box when you have finished the test. FOLD LENGTHWISE. Individual Raw Score Raw lly tA Model A. Pistol. POT ag Two sides properly joined with screw =—1; Hammer in place = +2; 2to 3 29 Spring in proper position = +7. Alton Saas OORT er o> Model B. Elbow Catch. aS) tO On a7 Catch in place=+3. Spring in place=+3. Pin in place = +3. 10 toIrl 39 I2to13 AI : I4toiI5 42 Model C. Rope Coupling. 16to17 44 Sere properly joined with screws=-+1; Center stud properly in ygto19 45 place = +5. Model D. Expansion Nut. 24to25 48 Rings in place and sides O. K. = +4; Nut reversed or bolt reversed =—6. 261027 49 Model E. Sash Fastener. 30 to 31 51 Top and Bottom in place, with screw in place, nut down=+3; Same, 34to35 54 with nut up = +2, I spring in place=+4; Both springs in place=+5. 36to37 55 38 to 39 «55 Model F. Expansion Rubber Stopper. 40to 41 56 Rubber properly on cone—+6. Bolt upside down = —4; nut wrong = a : 33 Te: 46 to 47 58 48 to 49 59 Model G. Calipers. 50 to 51 60 Spring in place on both arms with adjusting screw in place of eye =+5; 52 e 3 ye: Pivot in place=+2. Sleeve in place =-+1. Be to 57 62 , 58 to 59 63 Model H. Paper Clip. 60 to 61 64 Spring in place on jaws = +2; Pin inserted properly = +6; Pin inserted 62 t063 65 improperly = +1. 64 to 65 66 66 to 67 67 Model I. Double Acting Hinge. 68 oo se For each pin in proper place = +1. us iS a a 741075 71 Model J. Lock No. 2. rp enite oe Bolt in place=-+1. Lugin place=+1. Both in place=+4; Spring 78t079 74 in place = +6; Cover in place = +1. 80 to 81 74 82 to 83. 77 84 to 85 77 IEEME BONUS saree aes e NOTE TO SCORER: Score all perfectly 86to87 78 TOTAL assembled models 10. ‘‘—’’ means deduct 88 to 89 78 RAW SCORE een from 10. ‘‘+’’ means ‘add to zero.”’ 90 togr 80 92 to 93 «82 98 Measurements of Mechanical Ability SAMPLE SCORE SHEET SERIES III (Tentative) (Nearest Birthday) Grade: x.iaiincs be eas ae SCHOO seo ts Fee rete Datevor (Birth eee cee «eee ie SCORE SHEET STENQUIST ASSEMBLING TEST EBLE Sa ei vistiacore ates tts SERIES III (If less than standard) (For Grades 2, 3, 4, 5 and 6) NOTE: Place this sheet inside the box when you have finished. Fold lengthwise. SCORES: Model A. Plain Bolt and Nut No partial score. Right or wrong. Not necessary to screw nut up tight. Score: 0 or IO Model B.—Bolt and Wing Nut. (Perfect Score =10.) Nut reversed =plus 2 only. Model C.—Plain Hinge. (Perfect Score =1o.) Two halves joined, but one part inverted: plus 2. Pin inserted in one part only =o. Score: 0, 2 or 10. Model D.—Key and Ring. (Perfect Score =10.) Key only half on ring =plus 2. No attempt =o. Model E.—Turn Buckle. (Perfect Score =10.) Screw eyes properly in one end only =plus 2. Not necessary to screw up tight. Model F.—Drawer Pull. (Perfect Score =10.) Washer wrong in any way, subtract 5. Finished surface on wrong side, subtract 4. Model G.—Trunk Caster. (Perfect Score =10.) For failure to push pin clear through, subtract 8. Model H.—Plain Push Button. (Perfect Score =10.) For button out of place, subtract 6. Parts merely laid together (not screwed up) score I only. Model I.—Belt and Buckle. (Perfect Score =20.) Permanent end properly fastened, score 10. Loose end properly buckled, score 5. Strap not reversed (right side out) credit 5. Subtract same amounts for each step wrong. Model J.—Nail Clip. (Perfect Score =20.) Jaws and pin properly in place, score 10. Spring properly in place, 10. Spring reversed, 5. TOTAL SCORE: MECHANICAL APTITUDE TESTS INSTRUCTIONS FOR GIVING TEST I Pupils must be seated so as to prevent copying. Desks are cleared, pencils provided, and monitors pass out booklets, one to each pupil. Examiner instructs all pupils to fill in properly the heading on the blanks, being especially careful to obtain the correct age—by last birthday. Examiner says: ‘‘Lay pencils down! Before you begin I will show you ex- actly what you are todo. Let us read the directions.’’ Examiner then reads aloud the instructions on the front page, while the pupils read silently. Ex- aminer then asks if all understand. If some do not understand, repeat as much as is necessary. Examiner now says: ‘‘Open your booklets to Exercise 1, and turn the op- posite page under like this.” (Demonstrate. The pictures of Exercise 6 which appear upside down on page opposite Exercise I are then out of sight.) ‘‘You see that there are 3 problems in Exercise I all like the sample test on the front cover which we have just looked at; do them all in the same way. When you have finished Exercise 1, turn the page over and do Exercise 2, then Exercise 3, then Exercise 4, and so on until you have tried them all. If you don’t know the right answers, guess. Write one letter in each square.” Repeat privately any instructions necessary. Each child must understand what he is asked to do. No child is expected to answer al] the questions cor- rectly, but he should try them all. Examiner must see that answers are being plainly written in the proper place; that is, in the blank spaces provided in the margins. Time: Allow 45 minutes if necessary. Booklets are handed in as soon as finished, but examiner should be careful not to imply by word or manner that this is a speed test. The intention is-to give all the time desired by 95 per cent of pupils. INSTRUCTIONS FOR GIVING TEST II Pupils must be seated so as to prevent copying. Desks are cleared and monitors pass out booklets, one to each pupil. Examiner instructs all pupils to fill in properly the heading blanks, being particularly careful to obtain correct age—by last birthday. DIRECTIONS FOR EXERCISE I Examiner says: ‘‘Lay pencils down. Before you begin I will show you ex- actly what you are to do. Turn to Exercise 1. Let us read the directions.” Examiner reads aloud, and pupils silently, the directions for Exercise I printed 99 100 Measurements of Mechanical Ability in test booklet. Examiner must read slowly and point out ‘‘picture T’’ and “‘picture H”’ while holding booklet up before class. Examiner must also point out where letters T and H are written in the space for the answers. As soon as all the pupils understand what they are to do, say: ‘‘ Ready—begin.”’ At the end of 10 minutes, or when all have finished, say: ‘‘Stop. Lay pencils down.” DIRECTIONS FOR EXERCISE 2 ‘‘Turn to Exercise 2. Let us read the directions: ‘Look at Figure 1 on op- posite page, and answer as many of the questions below as you can. Answer each question with a single letter. If you don’t know, guess.’ When you have finished Figure 1, do the same for Figure 2, Figure 3, and Figure 4. If you don’t know what to do, raise your hand.’’ As before, instructions are repeated, if necessary, until all understand what is wanted. When all understand, examiner says: ‘‘Ready—begin.’”’ Allow 18 minutes. At the end of this time, or when all have finished,! examiner says: ‘‘Stop. Turn to Exercise 3.” DIRECTIONS FOR EXERCISE 3 Section A. ‘‘Look at the machine parts on the page opposite Exercise 3; now look at Figure 1 and Figure 2 in Exercise 3. Find where each machine part belongs in Figure 1 or in Figure 2. For example: part A belongs at I in Figure 1 or in Figure 2; so A is written beside 1 in the space for the answers.”’ (Point to pulley A and to the pulleys numbered 1 in the two figures so that all may see the correspondence.) ‘‘ Part W belongs at 2 in Figure 1 or in Figure 2; so W is written beside 2 in the space for the answers.”’ (Point to pulley W and to pulleys 2.) ‘‘In the same way find which of the machine parts belong at 3, 4, 5, etc., in Figure 1 or in Figure 2, and write the letters opposite these numbers.”” Allow 10 minutes. Section B. ‘‘ Now read all the questions in Section B and answer as many of them as youcan. If youare not sure, guess. When you have finished, hand in your booklet.’”” Allow 12 minutes. As the nature of this test is somewhat unusual, the examiner must make sure that the pupils understand what is required of them, and for this reason direc- tions may be repeated, or given privately to any pupil who does not understand. The examiner must not, of course, indicate or suggest what is the correct an- swer in any case, when repeating instructions. Examiner should see that answers are being written in the proper place. DIRECTIONS FOR SCORING These tests have been carefully planned to permit of rapid and accurate scoring. All answers are designedly placed at the extreme right-hand margin for each exercise, to facilitate easy checking of answers. All answers are either right or wrong. To find the number of correct answers, place the closed test booklet face up on the cardboard key, allowing the latter to project at the right-hand edge sufficiently to expose list of correct answers for Exercise 1; now open booklet to Exercise 1 and check off, with ink or blue pencil, each right answer, counting as 1If they finish before time is up. fs 9 Appendix 101 they are checked. Write the number of correct responses at the foot of the column. Then turn to Exercise 2 without removing booklet, pulling the book- let slightly over to the left on the key to expose list of correct answers for Exercise 2, and continue checking and counting the right answers as before. Do the same for all the exercises. Then copy the exercise scores on to the front page and add to find the Total Score. Then fill in the corresponding T-Score from table. In the case of Test I the booklet is reversed to correct Exercises 4,5,and6. 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