Journal of Psycho-As thenics

Monograph Supp lemen ts

VOL . 1 , No.

.

2 J U NE , 1915

LQualitativeDifferences Between L evels

of Intelligence in Feeble-M inded

Children

—By

Louise E llison (3\rdahl, Ph. D . and George O rdahl , Ph. D .

Pub l ished by Minnesota School for Feeb le-Minded

and Colony for Epi leptics, Faribault

Press ofM innesota School for Feeb le-M inded

and Colony for Epi leptics.Faribault .

QUAL ITATIVE DIFFERENCES BETWEEN LEVEL S OF

INTELLIGENCE IN FE‘EBLE-M INDED CHILDREN

B' LOU ISE ELLI SON ORDAHL, Ph. D . ,

and GEORGE ORDAHL, Ph. D.

Th is study was undertaken at Faribau lt,M i nnesota

,i n th e

p sycholog ica l laboratory of th e M i n nesota Schoo l for Feeb leM inded and Colony for Ep i l ept ics . Work was ‘begun June 6,19 14, and expe r iments were abrupt ly term inated October 2 6, 19 14 .

The p rob lem was suggested by Dr. F . K uh lmann,D i rector of

Research , who a lso rendered the au thors valuab l e ass i s tance i np lann ing and arranging experiments .

Th e B inot-S imon sca le i s a means o f measuring degrees ofgenera l intel l igence , but i t does not spec ifical ly revea l the qual itative d iff erences upon whi ch the variou s level s of int el l i gencedepend . Groups of ch i l dren , both no rma l and feeb l e-minded , maybe graded into d iff erent l eve ls o f inte l l igence w i th a cons i derab ledegree of accu racy . B ut the psychologica l qual i t i es c haracteristic of each group

,and the consequent qual i tat ive diff erences

b etween each level has not yet been determ ined .

In a genera l way i t i s qu i te apparent that th e h igher gradesdiffer w idely from the lower grades and i t i s qu it e possibl e todetect a cons iderab le d iff erenc e i n the behavi or of a group of

ch i ldren who are , for examp le , mental ly s ix years o l d and anot h ergroup whose menta l i ty is s even years , but j ust what th i s d ifference may b e p sycho logica l ly is not apparent . I t has thereforeseemed worth wh i l e to attempt a se ri es of exper iments cal cu latedto revea l a p sycho logi cal difference between the subj ects do i ngth e exper iments . Accord ingly th i s p rob lem was undertaken .

For th e pu rpose of t hi s study i t woul d be bes t to attemptexperiments on th e s imp le men ta l processes , and in th e fie ld al

ready la id ou t by norma l adu lt and ch i ld psyohology,and to se

lect exp eriment s for wh ich norm s are al ready estab l i sh ed andwh ich at the same t ime seem l i ke ly to yie ld resu l ts w ith th i s c lass

ORDAHL

of peop le . U n fortunate ly very few exis t which are at th e samet ime app l icabl e to the feeb l e-minded . The authors at tempted to

devi s e experiments wh ich shou l d t est the p sychologi ca l processescomprehended wi th in the fol lowing rubr ic s ' Sensory discriminations

, attention , memory , imaginat ion , j udgment , and reason .

The ind ividua l exp eriments are des ignated as fo l lows .

1 . Strength of grip,dynam'ometer .

Judgment of movement .Simp le reaction to sound .

Tapp ing tests .

Attent ion span .

D i scrim ination of grays .

Judgment of forms,two d imens ions .

Judgment of form .

Judgment of s ize .

Judgment of form,three d imens ions .

M emory for geometrica l forms .

1 2 . Modified typ ew ri t ing.

1 3 . Ink b lot test .14 . D rawing des igns i nverted .

15. Comprehens ion of comp lex d i rect ions .

Th i rty cases of typ ica l feeb le-m inded “ ch i l dren were se

lected , ranging between the chronologica l ages of fifteen andthi rty-five. I f i t was found that a case was suff eri ng from anyspec ia l defect such as fau lty vi s ion , i t was d iscarded and other

cases tr ied . However, al l defects , i f of a m inor degree , cou l d notthus be e l iminated s ince a case m ight be we l l along in the ex

periment‘before the defect Ibecame apparen t .

No cases were taken w'hose chronologica l ages were underfifteen . A ch ild under th is age wi th a mental i ty of ten i s possib lyquite diff erent from one of the same mental i ty but chronolog

ically o lder . I f a ch i l d i s fifteen and grades ten or lower in mental i‘ty 'he i s wel l poss essed of th e feeb l e-mi nd ed t ra its and compare s favorab ly with one of the same mental leve l but chronologically twenty or th i rty-five. I f

,however

,th e chrono logica l

age i s greater than t h i rty-five there is possib i l ity of deter iorat ion

p

o

wwo

we

w

s

i-CM

'

DIFFERENCES BETWEEN LEVELS OF INTELLIGENCE 5

having set in . For th i s reason ou r c ases were l imited to thechrono logical ages of fifteen to thi rty-five.

The cases were taken from th ree group s of ch ildren,whose

mental ages were s ix , ei ght , and t en , as determined by the B i net

S imon scal e . Ten cases were se lected from each of t hese three

menta l ages,

five gi rl s and five boys , thu s making an equa l number from each sex

,a tota l of fift een boys and fi fteen gi r ls . Sub

jects were taken who had not more than s ix months prev iousto the experiments test ed w i th i n two-fifths of a year of th e menta l age . The average chronologica l and mental ages for each

group were as fol lows .

Chronological Men talAge Age

Ch ronological Men talB y Sex Age Age

M enta l s ix—gir ls 2 1

M enta l six—boys 2 0

M enta l e ight—gi rl sM ental eight- boysM enta l ten—gi rl s 2 1

M enta l ten—boysThe chronologica l ages for th e di ff erent groups do not d iff er

greatly.The Ten group has the . lowest chronologi ca l average

wh ich may b e in it s favor . However , i t cannot“

b e much s inceth e d iff erence i s but one year l ess than the Six group , and

years l ess than th e E ight group . Whatever advantage th i s may

giv e the Tens over the other groups i s off set by the lower average menta l age which is . 1 year l ess than for the E ight group ,

and. 16 l ess than for the S ix group . The Tens are p laced at a

furth er di sadvant age by the fac t that the gi r l s of th i s group

ave rage s l ight ly be low ten years mental ly , and two have th e

mental age of 9 3 -5.In each of t he other groups no i nd iv i dual

was be low th e menta l age for th e group. The Tens are at afu rther d isadvantage from th e fact that two of i ts membersscored lower than the E ights in many of th e tests . Th i s was due

6 ORDAHL

in one case to a pecu l i ar d ispos i t ion wh ich preven ted the subj ectputti ng forth proper effort , and in the second case to a p ecul iari ty of vi s ion , and a defic i ency i n the genera l physical tonus .

The Eights as a group have an advantage of th e Tens intwo ways , fi rst , a s l ightly higher menta l average , and second ,there were two of i ts members who i n many of th e tes ts stoodabove the highes t Tens . These facts shou ld b e born in mindin read ing the various t ab les throughout th e fol lowing pages .

The figures are given as di fferent groups s cored , but for actua lgroup diff erences the Tens shou ld be s l ightly h igher and theEights s l ightly lower i n eve ry cas e

,thus mak ing the diff erences

between th e groups Eight and Ten great er than is actual lyshown by the tab l es .

Throughout th is study the terms S ix , Eight and Ten , when

cap ita lized , re fer to,or are abb rev iat ions for menta l age s ix, men

tal age eigh t and mental age ten . The number of cases in eachexper iment i s un iformly th i rty , and i s therefore not recorded in

th e tab les .

E xperiment 1 . S trength of Grip .

Each subj ect was tested for strength of grip in right and l efthand . Three trial s were given on each of th ree success ive days .

Smed ley ’s Improved Dynamometer was used and di recti ons fo ll owed as given inWh ipp l e ’sM anual of M enta l and Phys ica l Tests ,Vol . I , page 100 . The t est was given in th e presence of two

others of th e group . The subj ect was handed the dynamometer

after i t had b een fi t ted to h is hands , w i th th e fo l low ing remarks '

John,here

,has pu l l ed most one hundred pounds on th i s dyna

mometer. Let us see what you can do .

” Th is was usua l ly suf

ficient s timulu s to cal l fo rth cons i derab le effort , bu t i t i s sti l lquestionab le if the resu l ts record th e fu l l capaci ty of th e sub

j ects,esp ec ial ly w ith the lower grades who d i d not s eem to di s

t inguish be tween gri‘maces , contort-ions , and real mus cular ac

t ion . Severa l trial s were made on a subj ect w ith no others pres

ent . Th e great var iab i l ity i n th e resul ts led the author to d iscard

th is method s ince the resu lt s varied so much w ith d iff erent trialsthat i t was ev ident on ly a sma l l effort was being exerted

.W i th

D IFFERENCES BETWEEN LEVELS OF INTELLIGENCE7

the method used th e variat ions were on ly a few pounds.The

average i n K g . for th e groups were as fo l lows .TABLE I

Right hand L eft hand

Right hand L eft hand

Right hand L eft handS ix 26.

Eight

Ten

In two cases the l eft hand gr ip is greate r than th e right .One S ix boy has a record of s i xteen k i l ograms fo r the r ighthand and eighteen for th e left hand ; one Eight gir l has a recordof for th e r ight and 2 6 for the left hand . Th e diff erencebetween th e r ight and l eft hand grip i s not very large

,but i t is

suffi ci ent to show a d ifference , and that th e feeb le-minded is notnecessari ly ambi dextrou s as i s somet imes c la imed .

The norms given by Smed ley for 18-year-o ld boys and gi r lsare as fo l lows .

TABL E I I I

B oys Gi r l sRight hand L eft hand Right hand L eft - hand

Compari son w i th tab les 1 and 2 s how that the feeb le-mindedfa l l cons iderab ly be low the norma l for e ighteen year o ld boys

and gi rls . And the d ifference i s greater b etween th e feeb leminded

'

boy s and normal boys than i s th e diff erence betw een

feeb l e-m inded gi rl s and norma l gi rls .

E xperiment 2 . Judgment of Movement .

As a test o f ab i l ity to perce ive and est imate the extent of

ORDAHL

a simp l e movement , the fol low ing exp er iment was performed .

In a meter sti ck , five h ‘ol es large enough to accommodate a smal l

i ron sp ike , were dri l l ed at such d i stances that the spac e betweenthe hol e in the middl e of the bar and th e insi de edge of one hol eto the r igh t and one to th e left was twenty cent imeters

,and to

th e two extreme holes forty cent imeters to both s i des . A flat

wooden s l i de ab ou t one centimeter wi de was made to l i e flat

across the bar and s l i p eas i ly along i ts su rface where th e firstfinger was rested fi rm ly upon i t

,and th e arm moved to and from

the body . T-he meter bar was c lamped to the s ide of a low tab lebefore which sat th e subj ect

,and oppos i te h im the experimenter .

The whole Ope ration was conceal ed from the subj ec t by means

of a cardboard screen p laced horizonta l ly between h is hands andeyes . The i nst ruct ions given were ' Place your first finger on

th e l i ttl e wooden s l ide,move away from you when I say ‘

down’

un ti l you hit against the peg . When I say ‘

back’

move b ack

unt i l you h i t the nai l right in front of you . Move out again on‘down ’ and so on . When you have made th e movement th reetimes , . I shal l say ‘gone ’ and remove the peg ; then you are to

move to where you th ink you stopped before .

”The signal words

f ‘

down,

” “

b ack and “ gone” w ere given at a defin i te rate , oneevery hal f second , gone

,

”of cou rse , be ing the s eventh . After

a few preliminary tri al s to i n sure proper compreh ens ion of th e

i nstruct ions,regu lar work began . Fiv e trials i n each di rection

and to each of the two di stances from the cente r const i tu ted thetwenty j udgments compri s ing one day ’s work , and s ix days a

comp lete s et .

Tabl e 4 gives i n terms of cent imeters th e average amountof error for each age . Since there i s no ev idence of l earni ng

present , s i ngl e day’s resu l ts are not given .

TABL E IV

40 R Av . Errorss + — s + s + S +

S ix .3 .9 .s .9 . 9 .8

E ight 2 5 .4 . 7 .s .9

Ten .5 .6 .8 .9 .9 .9 .8 .9 5“

7

Columns headed show errors of over-est imation ;under—est imation ; “ S” th e ent i re number of errors i n any one

D IFFERENCES BETWEEN LEVELS OF INTELLIGENCE9

rubri c . Port ions of the tab le headed 2 0 and 40 give the t e

sults for both hands for the d is tances of 2 0 and 40 centimeters

respective ly . Those headed R”

and “ L give the resu l ts forboth d i stances for right and le ft hands respect ively

. U nder

average errors stand the average resu lts for the enti re 12 0

j udgments made by each subj ect . Therefore,column “ S” under

“

average errors shou ld b e the same as the average of co lumn Sunder 2 0 and 40, and the same as th e average of co lumns under

R and L . Column'

D . V .

” stands for th e average variation of

each indiv idua l’

s s i ngl e dav ’s work from hi s average for th e s ix

days . Column“

A . D . shows the vari at ion of one indivi dual ofan age group from other members of that group .

On th e whol e the diff erence between the three age l eve ls i sa lmost i ns ign ificant , th e p rocess probab ly being too nearly on amechan i ca l l eve l to b e much aff ected by superi ori ty or inferioritvof in te l l igence , but what d iff erence exists , is in favor of theh igher l eve l s . The D . V .

’

s i nd i cate that th e Tens are s tead i er

i n thei r work than lower ages . and the A . D .

’

s that th ere i s lessvar iati on of one memb er of the group from the others of the

group than there i s wi th the two lower mental ages . The most

i n teresti ng facts come out i n comparing th e p l us and m inu s er

rors , part i cu larly under 2 0 and 40 . U nder 2 0 ,we see that the

Sixes made a great deal larger p lu s than minus error . TheEights show qu i te a cons i derab l e p lus error

,whi l e th e Tens show

l i ttl e d iff erence ei ther i n under or over-est imat ion . Thi s mean s .

as observat ion of th e work also showed,that the lower l eve ls

exerted poor j udgment in making too great an innervat ion for th edi s tance they had to cover . They swung back and forth between

th e pegs w i th a j ar and trusted to the pegs to confine th ei r movements without trying to est imate the movement they were mak

ing,or to be gu ided by the i r est imat ion in their fina l j udgment .

Hence,the impetu s of th i s impu l se carri ed them beyond thei r

former s topping p lace . In the j udgment for 40 cent imeters ofmovement , more inh ib i t ion i s to b e overcome in making thelarger movement , and therefore th i s tendency i s not in evi dence .

There i s practi cal ly no di fference between the accu racy of the

two hands , as i s seen from resu lts under R and L . When re

w ORDAHL

duced to per cent . of d iff erence we have ' Tens, 100 ; Eights , 3 6 ;

S ixes , 24. The resu lts seem to i nd icate that the p rocess her.e i s

of so s impl e and e lementary a natu re as to h ave l it t l e dependence on degree of intel l igence , and that what difference exi sts ,i s p robably due to th e fact th at h igher l eve l s comprehend andobey the d irec t ions of the experiment more exact ly than sub

jects of l ess i ntel l igence .

E xper iment 3 . S imp l e Reaction t ime to Sound .

The apparatus used was Ewald ’s chronoscope and react ionkeys . The subj ect was instructed to ho ld th e l ever down andl et i t fly upon hear ing th e c l i ck of the meta l hammer . Th is metalhammer made e l ectri c connect ions and started the chronoscope .

The re leas e of th e l ever b roke the c i rcu i t and stopped the chron

osc0pe, wh ich counted the v ibrat ions of the vibrator, v ibrati ngat a twenty-fifth of a second . The subj ect seemed to find l essdi ffi cu lty i n l ett ing the lever go than i n p ress ing i t down . The

act of hold ing the l ever dow n seemed to keep h im in a more favorab le att i tude for rece iving the

“ ready” s ignal and reactingto th e sound . Whereas ,

if he he ld the lever t ightly be tween th efingers in p reparation for th e s ignal , attent ion was apt to

scatter .

The subj ect was seated beh ind a screen so as to shut off

a l l vi ew of th e apparatus and experimenter , bu t where th e ex

perimenter cou ld observe th e pos i t ion and movement of the sub

ject .Pre l im inary trial s were given so as to accus tom th e sub

ject to the apparatus and to acquaint him fu l ly w ith the obj ect

of the experiment . In the regu lar series 2 0 t r ial s were given each

day for five success ive days,or unti l 100 react ion s were taken .

The resu l ts for th e age groups,and for boys and gi rls togeth er,

are given in Tab l e 5.

TABL E VGroup average

4 115

.2759

2 3 85 .03 11

By th i s tab l e we see that th e Eights are super ior to theS ixes by second

,and th e Tens stand .o3 74 above th e E igh ts .

D IFFERENCES BETWEEN LEVELS OF INTELLIGENCE 1 1

Cons i der ing the h ighes t score as 100 per cent . , the difference between the mente l l eve ls i s indi cated as fol lows .

Tens , 100 per c ent .

Eights , 85 per cent .S ixes , 2 8 p er cent .

For th e feeb l e-minded th i s experiment i nvolves much morethan s imp l e vo luntary process es . For th em

,i t requ i res an act of

voli t ion of consi derab l e comp lexi ty . T he S ix finds i t an almost

i nsurmountab l e p rob lem to attend to one of the two foc i,viz .

,

the gri p on the lever and the hammer c l ick ab ou t to appear . Tofocus attent ion upon the gri p and at th e same time to maintainan ant ic ipatory att itude in the margin o f consciou sness for th esound of the hammer i s too much for h im ,

and to as sociat e two

images eff ect ive ly i s out of th e quest ion . He must at tend as wel las he can to one st imu lus

,forego any eff ectual anti c ipatory im

agery and make h i s assoc iat ion after th e second st imu lus ap

pears . Th'is i s tru e,but in much les s degree , of the E igh ts and

Tens . The experimen t i s va luab l e,however , i n showi ng th e

diff erence between the variou s leve ls of i nt e l l i gence in the ca

pacity for what to normal adu lts i s a s imp l e vo luntary p rocess .

E xperiment 4. Tapping Test .

As a test of susta i ned attent ionand voluntary effort , a s imp l etapp ing test was used . The apparatus con si sted of a tel egraph

key cl amped to th e tab l e and connected wi th an e lectri c counter .

A bel l was connected w ith a pendu lum to r ing every five seconds ,and the experimenter wi th l i tt l e d iffi cu lty l earned to read andrecord the counte r on the tap of the bel l . The subj ect was in

s tructed to tap wi th th e t ip of the thumb and fi rs t finger as fast

as possib l e , unt i l to ld to stop . The counter was in h is fu l l V i ewas h e w orked , to act as a spur , and prai se and flatte ry were l i

'

b

erally indu lged in to procure max imum effo rt . The series re

qu i red 24 minutes to perform ,and cons i sted of tapp ing al te rnate ly

with the r igh t and le ft hand twice , for one m inute each , w i th ani nterval of five minutes between succes s ive per iods of tapp ing .

Tab l e 6 gives th e numeri ca l resu lts of th e exper iment for the d if

ferent menta l ages . The figures give th e average number of tap smade for each age for each ten-second period . Thus S ix , column

ORDAHL

3 , shows the average number of taps made by the S ixes in the

th i rd ten seconds . A . D . i s the average devi at ion of each indi

v idual of that age from the general average of the group .

TABL E V I1 2 3 4 5 6 Av . A D .

.44

.49

.22

There i s some superiority of each age over the next lowestage , but not as much as might be expected from the resu l ts of

other experiments . The mo st i n terest ing fact is the shape of

the curve of a minute ’s work for the three ages . The S ixes start

low , ri se a l i tt le after ten seconds , and drop gradual ly un ti l atth e end of the fi fth ten - second peri od they are below thei r s tart

i ng point , when they spurt on the last lap to the i r h ighest po int .Thi s general tendency i s i nterest i ng in showing the i nhib it i on tobe overcome i n th e in i t ia l warming up process

,and the qu i ck

fatigue i n th e middl e of th e course . ' et , the poss ib i l i ty of the

sudden h igh ri s e at the end shows that, though the subj ect be

lieves he has b een exerting h imsel f , he has real ly been loafingat h i s task . The Eights start a l i tt l e h i gher than the Sixes , ri s e

by th e end of ten seconds and begi n to descend s lowly unt i l th ec lose

,when they are s t i l l h igher than at first . Here i s seen some

i nhib it i on at th e “beginning,bu t a greater capac i ty for susta ined

effort after sp eed is once up . However , the great var iat ion

among the Eights themselves makes any figures for them of only

general va lue here,for half the E ights resemb le Tens i n charac ter

i n th i s work,and a th i rd

,Sixes . The curve for th e Tens starts

h ighest and after the second ten seconds gradual ly decreases

unt i l i t reach es i ts lowest mark at th e end . The effort put forth

does not al low them to recup erate at the end for a spurt h igher .

Al l subj ects except one l eft-handed subj ect showed a h igher

average with the r ight hand , whi ch of course , i s the most prac

t i ced and the leas t fatigabl e .

As a means of fu rther studying the fat igab i l i ty of the d i fferent leve ls , the averages were computed for th e fi rst two trials

,

and the s econd two tri a l s s eparate ly . Tab l e 7 gives th e resu lt s .

U nder 1 i s given th e average of the fi rst tria l w i th both right

D IFFERENCES BETWEEN L EVELS OF INTELLIGENCE I 3

and left hands ; under 2, the second tria l wi th each hand .

Av

gives th e average for gi rl s and boys . The figures show that th e

s econd tria l s are poorer for the Sixes than the first tria l,whi l e

for the Eights and Tens,they are pract ical ly the same

.

TABL E VI IEight

1 2 1 2 1 2

This greater fat igab i l i ty of the S ixes i s part ly du e to fat igu e

o f attent ion , bu t p robab ly for the most part to the fact that they

a l l pounded the keys w i th great energy and were physi ca l ly

somewhat fat igued by the time they had fin ished . This ex

pend i‘

t ure of effor t on the ir part occurred desp it e the fact thatthey were al l to l d frequ ently to tap eas i ly

,and were shown

how to do so . I t i s j ust th i s lack of j udgment d isp layed here

that many s tudents of the feeb le-minded find so characteri st i c .

In terms of per cent . th e d i fference between the menta l age groupsi s ' Tens , I OO per cent . ; Eight s , 89 p er cent . ; Sixes , 82 per cent .

E xperiment 5 . V i sual Attention Span .

The materi a l u sed i n th i s experiment cons i sts (I ) of three

ser ies of exposure cards,A

,B

,and C

,th e first five of each of

whi ch are given in Plate I ; (2 ) sheets of paper contai n ing twentysquares

,each divided into four smal l e r squares simi lar to the ex

posure cards but lacking the stub l in es . The apparatu s used for

exposure was Wh ipp l e ’s Tach i stoscope . Each series of exposure

cards con tai n ed twenty two - i nch squares , each d iv i ded in to fourequal squares

.Short s tu‘b l i nes one-quarter inch long were d i s

tributed various ly around th e s i des and corners . These l i n es

may be p laced ac ross the corn ers , p roj ect from th e m iddl e of the

s i des at an angl e of n inety degrees or forty—five degrees ; neverat any o ther angl e or pos i t ion . Seri es A has one stub l in e i n

each exposu re card.Seri es B has two stu'b l in es and Seri es C

has three .

The subj ec t was requ i red to observ e the posi t ion and angleof th e stu 'b l i n es and to insert th em in blank squares p laced be

fore h im .The exposu re interval was s ixty sigma . The subj ect

was seat ed at a d i stance of fou r feet from the exposu re wi ndow

wi th eyes approx imate ly on a leve l wi th th e fixati on poin t . The

ORDAHL

Plate I

D IFFERENCES BETWEEN LEVELS OF INTELLIGENCE 15

fo l lowing di rect ions were given each subj ect b efore beginn ingth e experiment '

“

Noti ce the short l i n es are always across th e

corners , i n th e corners , or, as you see , at th e m idd l e of th e s i deand tu rned eith er straigh t or s lant ing. I am going to drop someo f the cards before the window . ' ou watch carefu l ly for the

short l in es so you can rememb er where they are and put them

in th e square before you j ust where th ey shou ld be.

” F rom five

to ten tr ial cards were then exposed fi rst for a longer and thenfor a shorter in terva l . As soon as th e subj ect seemed to com

prehend th e problem and to have adj usted agreeab ly to the s i tu

at ion , the regu lar series was begun . I f,however

,at th e end of

th e ten trial s it appeared th ere was no adequate comprehens ion,

the subj ect was al lowed to copy from the t r i a l cards i nto the

b lank square unti l h e understood what was wanted ; then th etri a l ser ies was repeated . This last procedure was necessary

w i th a l l bu t two of the S ixes ; al l bu t two of th e E igh ts , and a l lth e Tens ad justed to the experiment before th e tenth tr ialsome almost immed iate ly .

The score was obtai ned by count ing the numb er o f stub

l ines correct ly p laced . Each subj ect was put th rough each seri es once each day for ten su ccess ive days . The t ime requ iredfor a dai ly s i tt i ng of s ixty exposu res var ied between 15 and

minutes . The dai ly average number of correct cases for the

d iff erent age levels i s shown in Tab l e 8 .

TABL E VI I I4 5 6 9 10 Av . A.O .

SE RI E S A

.7

SER IES B

SER IES C

In seri es A th e Tens score an average of ab ove the

Eigh ts . Thi s d ifference a lone i s not suffi c i ent to ind icate a rea lsuperi or ity

,but th i s low score on the part of th e Tens is du e to

m ORDAHL

the fact that they were doing so wel l that they cou l d not fee lthe necess i ty of doing better . The E ights ’ score was slightlv

over doubl e that of the S ixes . The relation of the three l eve ls toeach other stand as fol lows '

For Seri es A ' Tens , 100 per cent . ; Eights , 92 percent . ; S ixes , 45 per cent .For Ser ies B ' Tens

,100 per cent . ; Eights , 84 per

cent . ; Sixes , 3 5 per cen t .

For Ser i es C ' Tens , 100 per cent . ; Eights , 79 percent . ; Sixes , 2 8 per cent .I t w i l l b e seen from the total average col umn of Tabl e 8

that th e d ifference between the ach i evements of the d ifferent

mental ages i ncreases from seri es A to C,or wi th th e increas ing

d ifficu l ty of th e se ri es . In seri es A ,th e S ixes are 45 per cent .

of the Tens , whi l e the di ff erence between the Tens and E ightsi s on ly 8 p er cent . In Ser ies B

, the S ixes are 3 5 per cent . of the

Tens,wh i l e th e diff erence between the Tens and E ights in

creases to 16 per cent . In Seri es C the S ixes fal l to 2 8 per cent .

of the Tens and th e d ifference between the Ten s and Eights i s

2 1 p er cent .The A series i s not a real test for ages above s ix . The

Eights score 75 per cent . and the Tens 82 per cent . correct

cas es . I f we consi der th i s score alone , i t appears that i t i sd iffi cu lt enough , bu t the exper iment d id not create a suffic ientdemand for effort . I t was easy enough after a few tria ls toobserv e th e correct pos i t ion o f one stub l i n e and consequent lythere was not suffic i ent effort put forth to prevent one from

s l i pp ing by occas ional ly . On the other hand , 3 5 per cent . of

th e correct cas es wou ld ind icate that th e test i s too difficu lt for

th e S ixes . But th ei r beh av ior and att i tude toward the prob lemshowed a c lear comprehens ion and a genera l endeavor to score ,wh i ch wou ld at l east ind icate that th e A ser ies i s a good measurefor effort of attention . At the same t ime i t gives the subjec t anopportun i ty to show whether or not he be longs to a h igher l eve lof i nte l l igence . The Eights make th ei r h ighest score in Seri esB . Li kewi se th e l earn ing curve i s h igher here than in Ser iesC , i nd icat ing that C i s too d iffi cu lt , ei ther b ecause they become

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18 ORDAHL

five tri a l s . The r ight hand column gi ves the gai n made i n th elast half of each seri es . There are on ly two cases out of the

th i rty who show any drop at a l l i n the second hal f and thes ep roved to be of an unstab l e nervous temperament

.The S ixes

make very l i tt l e ga in in any seri es . The gai n for the E ights i nSeri es B and the gai n for the Tens in Ser ies C i s rather l ight

,

but greater gain i s made by the end of the fi rs t hal f o f the ser ies,

or by the fi fth or sixth tri a l , so that the gain i s made by hold ingthe score reached by the end of th e first ha lf.

In order that the tes t may be un i formly one of attent ion span,

each posi t ion of the stub l ine in Seri es A shou ld be as diff icu l t asanother , and in Seri es B and C , each group of stub l i nes , or th e

stub l ines grouped i n one exposu re shou ld be as d ifficu l t of p erception as th e group found in any of the oth er exposures o f th e

seri es . This does not seem to have been the case,and i t is per

haps not poss ib l e to d istr ibute the l i nes over th e fie ld so as to

make the large squares of equal or of a grad uated di ffi cu lty ofp ercept ion . In Seri es A

,Nos . 10, 19 , and 2 0 gave spec ial diffi

cu l ty , and there was -a genera l tendency to get the l i nes of the

lower square i nto th e upper squares . In Ser i es B,No . 1 3 was

eas i est , No . 16 qu i te as d iffi cu l t as any . In Ser i es C,No . 8 was

among th e fi rs t to be gotten correct ly . In general , the l i nesabout the center of the square where d istances were les s , wereth emost confus i ng . Two l ines i n the same smal l square c los etogether o r on th e right or l eft s ide of the large square presented l ess d ifficu lty

,a l so l i nes of s imi l ar qual i ty . Th ere seems

to have b een con fus ion when the l in e of v i s ion passed the crossl i nes of th e large squares . This may b e due to th e tendency of

the eye to fo l low the l ines or simp ly to the‘greater comp l ex i ty

of the perceptual image . I t wou ld seem that one large squarew ith the stub l in es d i stributed around the s ides and cornersmi gh tmake a test more nearly free from the d i sturbance of ,

ex

te rna l factors . Someth ing on th i s order wou l d have the advantage of greater s imp l ic ity

,and the stub l ines cou ld be more eas i ly

grouped in order of difficu l t .

The experiment has revea led th ree diff erences i n the mentallevels chosen

,v iz . , d ifferences in comprehens ion of simp le p rob

D IFFERENCES BETWEEN LEVELS OF INTELLIGENCE 19

l ems , adj ustab i l i ty , and attent ion span . The fi rst two are notmeasurab l e in mathemati ca l terms for th i s exper iment but can

be ind icated . The Sixes had vi rtual ly to b e put through the

experiment before they cou ld comprehend i t,and they requ i red

th e longest time to adj ust even inadequately to the s i tuat ion.

The Eights can comprehend more eas i ly,but requ ired concrete

demonstrat ion , and adj usted more s lowly than the Tens .The

Tens comprehended from a verbal exp lanat ion and took up theprop er att i tu de for work and adju sted most read i ly wi thi n fivemi nutes .

D ifferences i n attent ion span are fai rly represented in termsof percen tage ' Tens , 100 per cent . ; Eights , 84 per cent . ; S ixes ,45 per cent .

E xper imen t 6 . D i scrim inat ion of Grays .

As a test of sensory di scrimi nation,match ing d iff eren t

shades of gray was used . The apparatus consis ted o f a card board

about 1 2 x 18 inches , i n whi ch were fifteen Open ings two inchessquare , arranged i n three rows of five squares each . In eachsquare , except th e middl e on e , were

”

pasted from one to fourteen

th i cknesses of wh i te t is su e paper , one th i ckness in th e firsti ncreas ing by d i rect increment of on e up to fourteen . Around the

middle open ing were arranged str ip s of cardboard to form a

cas ing i n wh ich to s l i p smal l square frames . There were four

teen of these frames cons isti ng of two- i nch square p ieces of

wh i te t i ssu e paper,each frame hold ing th i cknesses varying from

one to fourteen p i eces to correspond w i th th e open ings i n th el arge card . The card wit h the fi fteen open i ngs was pasted flat

against a ground glass w indow w ith a north l ight , and the sub

j cet seated di rect ly i n front of i t . (O f course the l igh t show ingthrough the papers wou ld p roduce th e brightest gray in the

square w i th one th ickness of paper and th e darkest for th e four

teen th icknesses ) . A smal l frame was then s l ipped into i ts p lace

in the m iddle Open ing, and th e subj ect to ld to poin t to th e gray

j ust l i ke this one .

” A constant i rregu lar order was used to in

su re procedure .w ithout know ledge of th e subj ect . M atch ing

each of th e fou rteen grays tw ice compr i sed one day ’s work , and

2 0 ORDAHL

three days , or eighty-four j udgments for a subj ect,consti tuted

a tes t .

Al l subj ects comprehended th e task read i ly,yet i t was d iffi

cu l t to get some of the lower grades to take the t ime and painsto rea l ly d iscr im inate . Then , again , th ree of the Tens took somuch time to make thei r deci s ions that after-images and fat igu emust have had someth ing to do i n affecting the value of thei rj udgment .

In scori ng a j udgment , th e amount of error for that j udg

ment was es timated by the d is tance in the scal e of grays lyi ng

b etween the gray chosen as i denti ca l w ith th e standard and th eone actua l ly i dent ical . For example

,i f gray number 14 was

shown , and the number 1 2 point ed to as i den tical , the e rror was

recorded as 2 , or i f 13 was chosen when 10 was shown,the error

amounted to 3 . The average for each day ’s tri a ls was taken andthe average for the ent i re th ree days ’ work . Since th ere was no

evidence of effect of pract i ce , on ly the average resu l ts are given .

which are conta ined in Tab l e 10.

S ix E ight Ten

The errors for al l l evel s are su rpr i s ingly few ,though S ixes

show a score of errors twi ce as large as that of the oth er ages .

The three l evel s wou l d have been more nearly equal but for

four very carel es s S ixes . In term of relat ive percentage i t

amount s to , Tens , 100 ; Eight , 98 ; Sixes , 80 .

The fo l lowing tab l e gives th e average error for each

part icu lar gray ,ranging from one

,which stands for br ight

est,to 14, the darkest . Natura l ly the eas i est grays to d iscr im

inate i n th i s s er ies are th e br ightest , and the most d ifficu l t the

darkest .

fPAdal J E IKI

l 2 3 4 5 6 7 8 9 10 11 12 13 I4

The S ixes make abou t the same amount o f error for each

D IFFERENCES BETWEEN LEVELS OF INTELLIGENCE2 1

gray , show ing that i t i s not for them so much a matter of d ifficu l ty of di scrim ination

, as whether they cou ld attend c loselyenough to compare . The Eights show more nearly the error

curve we shou ld expect , excep t i n th e b ig drop in the middle

at seven . Here aga in attent ion i s the factor wh ich exp la ins,for

seven was to th e left of the window into whi ch the variab l e

gray was s l id , and the one wi th which i t was natural to comparei t . Hence , fewer mistakes were made here than might be ex

pected .

The experiment , on the whole , does not seem a part i cu lar ly

good one for detect ing d i fferences in mental l evels . In fact, re

sults i nd icate that when an imbeci le can be i nduced to attend,

h i s powers of di sc rimination are ab out equa l to those of a moron.

But th e fact that h e concentrates perfect ly one m inute andwanders the next , makes th e resu l ts l ess va luab l e as cr i teri a of

di scrim inab i l i ty than of attent ive capac i ty .

Experiment 7 . Judgment of Forms .

I t is qu i te evi dent that feeb le-minded ch i l dren and adu ltshave sensat ions not great ly diff erent from normal persons except i n th e time of respons e . The difference , then ,

shou ld l i ei n what m ight be termed the manipu l at ion of mental e l ements

or mental imagery . We have attempted an expe riment whi chshou ld test th e re lat ive ab i l i ty of th e diff erent menta l ages to

rece ive,retai n and transfer imagery from on e sense to another .

A number of forms were cut from thi ck pasteboard and

mounted on other pasteboard cards five inches square . The

subj ect was al lowed to pass h is hands under a c loth screen andto feel of th e form by pass ing h i s fingers around the edges and

over the top whi l e i t was he ld i n a stat ionary pos i t ion . After

th i s he was requ i red to po int out the form j ust fe l t among

the ten forms drawn fu l l s ize on one large card . The subj ect was

given d i rect ions as fo l lows ' “ Put you r hands under th i s c lothand fee l of a form there someth ing l i ke th i s one , un ti l you aresu re you know what i t looks l ike , then I w i l l l et you see thesedrawings

,and you are to poi nt out w h ich one you have j ust

fe lt .”

The seri es was presented once each day for five success i ve

2 2 ORDAHL

days , one tria l be ing al lowed for each form ,or 40 tr ials i n a l l .

The resu l ts are given i n Tab le 1 2 .

TABL E XI IAv . dai ly Av . to talerrors errors A.D .

Accord ing to Tab l e 1 2 the average errors for five tr ia ls i snot large for E

‘

ight and Ten . In terms of per cent . the diff erencebetween th e l evels stands thus ' Tens

, 100 per c ent . ; Eights , 90per cent . ; S ixes , 45 per cent . Fol lowing the dai ly score fromle ft to right , i t wi l l be noted that l earn ing i s qu i te rapid forTens and E ights . When we add to th i s the fact that errors werea lmost constantly made on three part i cu lar forms

,the experi

ment does not appear to have mu ch valu e . I t may,however

,be

a test of supefficiality s ince i t wou ld have been qu i t e poss ibl efor the Eights and Tens to have made an almost perfec t record .

They were sat i sfied wi th approximate certai nty . The characteristic to b e content with approximate resu l ts and to over looksmal l bu t essenti al d ifferences is not so apparent in exper imentsthat at onc e chal l enge effort and put th e subj ect on h is mett l e .

E xperiment 8 . Judgment of Forms, Two Dimens ions .

On account of th e rel at ively unsat i s factory resu l ts found inexperiment No . 7, that experiment was mod i fi ed and another ex

periment attempted . This conta i ns th e same forms as E xperi

ment No . 7, but they were rendered more difficu l t by cutt ingoff corners and thus changing thei r shape . The procedure was

further changed by a l low ing the sub j ec t to observe th e forms h ehad felt i n stead of the drawings of them . Thi s changed two

factors s imu ltaneous ly w i th th e resu l t that we cannot ascribed i fference in resu l ts to ei ther of the two factors , more d i fficu l t

forms,and the observat ions of actual forms instead of drawings

of them . However, a few forms were not changed but remained

th e same for both exper iments , 7 and 8. Compari son of the

b lanks for both experiments show on ly a very s l ight improvement in Exper iment 8 for forms not changed

,wh i le for the

changed forms , the score immed iately drops off. Th i s would in

D IFFERENCES BETWEEN LEVELS OF INTELLIGENCE 2 3

d icate that there .i s l i tt le d iff erence in observing actua l forms ord rawings of th e forms . However

,there was a greater in terest

i n choos ing the correc t forms from the real forms than from

draw ings . The resu l ts of the experiment are given in Tabl e 1 3 .

TABL E XII IAv . dai ly errors

I 2 3 4 5 errors A.O .

The re lat ive differences between the age l evels are ' Tens , 100per cent . ; Eight , 78 per cent . ; S ixes , 2 0 per cent .

The diff erences here i n scores are more marked than in

Experiment No . 7 . There i s n eed for greater attent ion ; di scr imination i s finer and the process of i dent ificat ion more comp l ex .

An d yet i t appears that the fundamental process i s one of transfer of touch and kinaesth et ic imagery to vi sua l imagery . I t isprobab l e , however, that th e d i scrimi nat i on i s due to p ract ice ina l ternate feel i ng and seeing s i nce an express ion of recogn it i on ismade on feel i ng of an obj ect wh ich has been , j ust p revious ly .

the foca l po int o f attent ion . I t becomes,th erefore , the recal l

o f a vi sual image through touch and the recogn i t i on of this imageth rough vi sion . In fee l ing of an obj ect not yet seen , th e

‘image

i s indefi n i te unt i l i t has been seen . Wh en the second touchmotor experi ence takes p lace

,th e proces s i s s imu l taneously

touch -motor—vi sual .The tes t is not a good one for th e S ixes . The ch i ldren of

th i s l eve l do not have the necessary capac i ty for susta ined consecutive

'

thought . The low score wou ld ind icate that th e S ixesare out of cou rt here . Chances a re one in ten for a correct score ,

wh ich lowers th e actual choi ce and renders the test unfit . B e

s ides the att i tude in renderi ng a cho ice ind i cates they were making a wi ld guess .

0

The p rob lem i s ent i re ly with i n the capac i ty of the E ights

and Tens,but Exper iment 8 is superior to Exper iment 7, s i nce

i t ca l ls for c lear attent ion and finer d iscriminations . The norms

for th i s tes t shou ld b e 50 per cen t . correct for Eights and 70per cent . for Tens .

24 ORDAHL

Experiment 9 . Judgment of S izes, Two D imens ions .

Thi s experiment was des igned for the same general purposeas seven and eight , and is constructed on the same p lan , except

that th e forms remain cons tant wh i l e th e s i z e vari es.Four d if

ferent forms were used , the ci rc l e , rectangl e , tri angl e and square .

These s izes were made from heavy cardboard and mounted on

cards five i nches square . The procedure was th e same as inExperimen t 8 . The dimens ions for the forms are given in

Tab l e 14 .

TABL E XIVCi rcles D iameter Squares Side Rectangles T r iangles Base Altitude

1 . 144 in . 1 . i n . 1 . 1 x2 in . 1 . i n . 1 1762 . 2 i n . 2 . i n . 2 . 1 34 112 174 i n . 2 . 2 in . 2

3 . 214 in . 3 . 1 34; in. 3 . 1 175112 174 i n . 3 . 2 175 in. 2 1764. in . 4 . 2 i n . 4. i n . 4 . 3 in . 3

5 . 2 974 in . 5 . in . 5 . 1 554 113 in . 5 . in .

The forms were presented once each day for five success ive

days , thu s mak ing 2 0 t rials each day,or 100 tri a l s i n a l l . Errors

were determined by counti ng the number of p laces a s ize wasremoved from the correct p lace

,e . g.

,i f th e subj ect j udged No . 1

to be No . 2, the error wou ld b e one . I f No . 3 was j udged to b e

No . 5, th e error wou ld be two . S ince th ere are five s i zes cal l ed

for i n each form,the h ighest poss ib l e error for any j udgment i s

fou r,and for the fou r forms given at one s i tt ing i s 80 . I t wou ld

th erefore b e poss ibl e for a subj ect to score 400 errors for the five

s i tt ings . Tab l e 15 shows the resu l ts for th is experiment .

TABL E XVAv . dai ly errorsof all forms Av . A.D .

This experiment i s too difficu l t for th e mental S ix . I t wasqui te ev ident that h is j udgments were largely acc idental . However , his error for any one j udgment i s rare ly over two , but com

mou ly one . The E‘i gh ts and Tens compreh end the prob lemreadi ly and have very defini te feel ings as to th e correctness o fthei r j udgment . However , i n the fi rst t ri al s th ere i s a feel i ng of

uncerta inty , and the subj ect wi l l remark '“Wel l

,I don ’t know

,

I am guessi ng.

” The guess , however , is more oft en correct than

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ORDAHL

Plat e I I

D IFFERENCES BETWEEN LEVELS OF INTELLIGENCE 2 7

ences as are seen in Experiments 7 and 8 . The S ixes can distinguish very s impl e forms , bu t cannot p roceed beyond these .

Th e differences a re ' Tens , 100 p er cent ; Eights , 71 pe r cent . ,and the S ixes per cen t .

A few forms were re cogn ized by a l l—the cube , t he rectan

gl e and the d ivided cubes . 6 and 7, were most often confus ed andp resented d iffi cu l ty to al l sub j ec ts . Th e Tens adj ust th e mostreadi ly , th e Eights more s lowly and the S ixes not at al l . Theexp eriment offers opportunity to observe the readiness of ad

j us tment on the part of the subj ec t . There are many forms sos im i lar that they could b e di s tingu ished an d d ifferent iated on lythrough t r ia l and error . The psycho logi ca l p rocess is d ifficu ltto dete rm ine s ince int rospect ion i s much n eeded h ere for anyth ing l i ke a correct i nterp retation ; but introspection i s some

th ing the feeb le-minded cannot furn ish . A few i l lus ions ev idently ar is e wh ich di s app ear on ly w i th d i rect compari son . A

large port ion of the fo rm comes immedi ately as one passes thefingers over th e b locks , or shoots i nto form as th e fingers turnthe corners or measu re the angl es . B ut even with this imme

d iate flash i nto consc ious nes s there remai ns a certai n indefi n i teness to th e imagery unti l the obj ect i s observed v isual ly . After

getting the touch and kinaesth et ic experi ence i t remains for th esubj ect to reta in the image agai nst th e v isua l percep t ion of many

forms,some s imi lar

,un ti l th e form ident i cal w i th h i s image i s

sighted .The subj ects d iffer appa rently i n two ways . One c las s

was “ impress ion i st” and th e o ther “ rat iona l i s t .” The former

are vi sual i sts and do not consc iou s ly tu rn over the im

agery menta l ly,but re ly upon a feel ing of fami li arity to de

term ine thei r choi ce as they looked over th e fi el d of 20 b locks .

The second c las s wou l d note s imi lar i t i es , but they wou l d fix upon

one essenti a l d i fference and re ly upon th is factor for th e cho iceo f a b lock

.Those who pursu ed the latter method were ab le sev

era l days after th e l ast t ria l had b een conc luded to p ick out th eform fe l t when th e b locks were p i l ed m iscel l aneous ly in a heapon the tab le

,w i thout a s i ngl e error . The

“

impress ion i sts”

were

not ab l e to do th i s and when asked to ind icate how they dis

tinguishedth e forms one from the other, cou l d not do so . D i s

2 8 ORDAHL

cr iminat ion by noting carefu l ly the characteri s t i cs o f the obj ec twas common to both Eights and Tens . But the Tens exerc i sed

more control than did th e Eights . The exper imen t cal ls for perceptions of relations , capac i ty for forming clear-cu t d ist inct ions ,and a certain smal l amount of reason ing . Whi l e i t i s not an ah

solu te ce rta in ly , there are c erta in s trong indi cat ions that i t re

qu i res some menta l effo rt to make the trans fer from a touch

kinaesthetic imagery to v i sual , and that th i s experiment revealsthe p rocess i n an e l ementary way . The expe riment as a whol ewas more in te res t i ng to the subj ects than Experiment No . 9 ,

and for thi s reason is superi or as a ment al test .

Experiment 1 1 . M emory for Geometri cal Forms .

As a tes t of s imp l e v i sual memory , ten card-s , each contai n

ing a geometrical form were us ed . Each for-m cons i sted of a ci r

cl e two inches in diameter, with th e di ameter drawn through i t

hori zontal ly,vert ical ly

,or at 45 degrees from eithe r hori zonta l or

verti ca l , one or two one- i n ch l in es ly ing outs ide th e circl e as tangents

,and one or two one- i n ch l i nes lyi ng in side as chords , t here

being alw ays fou r such l in es i n al l to a ci rc le , as shown i n Pl ateI I I

,A . S ince each drawing was en ti re ly d ifferent , by tu rn i ng a

card in each of th e fou r poss ib l e pos i t ions , fo rty i nst ead

of ten vari at ions of form were produced . The ca rds

were p laced in two para l l e l rows on a tab le at wh i ch

the subj ect sat,the order bei ng a defin itely p lanned i r

regu lar on e,to avoi d th e factor of p lace memory . A

cloth curtai n hung before the subj ect to conceal op erations .

The subj ect was told ,“ I am going to show you a card w i th a

drawing on i t,study i t

,and aft er t en s econds I shal l take i t

away,and you must pu l l the cu rtain as ide and poin t to th e one

you have been studying. The card was s l ipped under the cur

tai n and shown to him for th e ten seconds , and immed iate ly

put back into p lace , wh en h e tri ed to p ic k i t out from the other

d raw ings . After the ten cards had been exh ib ited , th ey were

p la ced in th e s econd posi t ion , then in th e th i rd and fou rth , thu s

mak ing fo rty tria l s in a day ’

s work . Three days ’ work of 1 20

t rial s for each subj ect cons t ituted a comp l ete s eri es .

D IFFERENCES BETWEEN LEVELS OF INTELLIGENCE 2 9

P late I I I

30 ORDAHL

After th e above experiment on immediate recal l,a s im i lar

one was used for delayed reca l l,th e on ly d i fference in method

being that the subj ect wai ted ten seconds after having seen th e

card before h e tr ied to s elec t it from the others.Here

,ow ing to

necess i ty of l eaving exp erimentat ion enti re ly , on ly two days ’

records were taken and on ly tw enty judgments on each day,

mak ing forty the tota l number.In a th i rd experiment the delay was extended to one m in

u te . S ince on ly ten j udgments cou ld be a l lowed here,th e resu lts

do not bear a va lue ent i re ly comparabl e with those of the firsttwo forms of th e exp er iment , but the resu lts are given for whatth ey are worth .

Tabl e 17 gives the average percentage of correct cases foreach age of th e three forms of the exp er iment

.

TABL E XVIIImmediate 10-second l -mlnaterecall i nterval i nterval16 2 0 20

56 55 63Ten 77 90 85There i s qu i te a di s t inct and remarkab le diff erence between

the di fferent age l eve l s . The S ixes do pract ical ly noth ing,the

Eights get about hal f , and the Tens more than th ree- fourth .

Th e task of d isc riminating the differences between the arrangement of mean ingless l ines was too comp l i cat ed and di ffi cu l t ap roblem for the weak attent ive capacity of th e S ixes . M emoryhardly seemed a factor h ere

,j udging from thei r carel es s manner

o f s tudyi ng the card dur ing i ts expo sure and the haphazard way

i n which they made th eir se l ect i on when i t was t ime to j udge

what card they had seen . Th e E ight s were more sensib le i n

th e i r methods , but i t is probab l e that here , too , d iscrim i nab i l i ty

and attent ive capac i ty was an important factor .

Reduced to per cent . diff erence,the three ages stand

Immed iate recal lS ixes , 2 0

Eights, 72

Tens , 100

D IFFERENCES BETWEEN LEVELS OF INTELLIGENCE 3 1

Ten seconds delay

S ixes, 2 2

Eights, 60

Tens, 100

One m inute delayS ixes

,2 3

Eights, 74

Tens, 100

For th e Tens on ly i s there any cons i derab le di fference between the th ree forms of reca l l , who profi t by the ten secondinte rva l s , and are bu t a l i tt l e lower a fter one minute i nterval

,

though higher than i n immediat e recal l . Indiv i dua l figures showno l ea rn i ng for any age , excep t for th e Tens

,and here on ly a

very s l ight degree .

The experiment demands too great a degree of attent iv e capacity for the Sixes , so that whatever value i t m igh t have asa meas u re of retent iveness is e l im inated . Perhaps i t is even al i tt l e too d ifficu l t for th e Ei ghts , but for Tens i t m ight make agood mental test , i f 70 per cent . or more correct j udgments wererequ i red , with an improvement in the case of de layed reca l l .Eights shou ld be requ i red to get about hal f th e cas es righ t for

immediate recal l and do at least no worse in delayed recal l .E xperiment 1 2 . Modi fied Typewri ter .

Th is was an experiment i n l earn ing a connected seri es ofvi sua l-motor coordinat i ons . The apparatus us ed was an ar

rangement resembl ing in pr inci p l e a simp l e typewrit er of fou rkeys . On each key was pasted a colo r , and when any key waspress ed a d ifferent color app eared j ust abov e it , t hrough a sloti n a vert ical screen , whi ch was the color of th e n ext kev to bestruck . A red key th rew up ye l low ; a ye l low , b lue ; a b lue , green ,and green , red , the last key of the seri es th row i ng up the color

of the first , making an un interru pted process to be cont inued unt i l a s i gnal to stop . Each key was connected wi th an e lect ri calcounter , so that every stroke regi stered a count . A bel l was con

nected wi th a second pendu lum to ri ng once every minut e,as a

s i gnal for st art i ng and stopping . The errors were eas i ly ob

se rved and recorded by the expe rimenter . After th e prin c ip l e

3 2 ORDAHL

of th e apparatus and the task was exp lai ned briefly to the sub

ject , he was al lowed a few tri a l s to make su re that h e understood.

Every subj ect was i ns tructed to use fou r fingers,the first and

middl e finge rs o f both hands , and to stri ke each co lor wi th i ts

own part icu lar finger . But the latter was imposs ib l e for s ome

subj ects , and though al l were given th e same inst ruct ions , on ly

part o f them succeeded i n us i ng four fingers . Ten one-minute

t ri al s a day wi th a m inute interva l between succ ess ive tr ials and

s ix days’

work cons ti tuted a regu lar s eri es . When resu lts in

dicated th at th e s ubj ect m ight b e abl e to work w ithou t th e a id

of th e visua l cue , a cardboard screen was p laced to concea l both

the co lors on the keys and the smal l co lors the keys showed on

be ing p res sed . Where a subj ect cou ld not work wi thout th e ai d

of v i s ion at th e end of six days of p ract ice , th e seri es was con

ti nn ed for fou r more days . The nume ri ca l resu l ts show on ly six

days ’ work . Throughout , the subj ect was kept i n formed as to

th e score and m is takes .

The p rob l em for the subj ect then i nvolv ed a seri es of

fou r motor reac t ions to sp ec i fi c v i sual cues . I t comp r ised the

p ercep tion of th e colo r shown th rough the s lot , th e percep t ion

of the key w i th th e same color pas ted on i t , the cho ice motor re

act i on i nvo lved in the p ressu re of that key , and th e choi ce of

th e finger used .

Tab le 18 shows the resu l ts i n numeri ca l form for th e di ffer

ent menta l ages .

“ S” i ndi cates the number of st rokes i n a min

u te,

“ E” the number of errors,and “

C” is “

S”minus

“

E ,

”or th e

correct strokes . The figures at the head of the col umns ind icate

days . Thus th e figu re under S ix,co l umn 6,

“ S ,

” s tands for the

average s trokes made by the S ixes on the sixth exper imenta l day .

Co lumn A . D . gives the average devi at ion of each ind iv idual

of the group from th e average for that group .

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34 ORDAHL

be the most d ifficu l t task of al l and only two of the Sixes succeeded in‘ doing so , even after the t enth day Ha l f of th e E ightsmanaged i t , w i th cons iderab le di ffi cu l ty

,but a l l of the Tens were

u s ing fou r fingers by the end of th e second day ’s work.

O fcours e , th i s was a more econom ica l method i f i t cou ld once beacqu i red and resu lted in a qu icker mechan izat ion of the p rocessand a more rap id rate of work . For h alf of the E ights and a l lbut two o f the S ixes , i t was too comp l icated a matter to di s ti ngu i sh the p roper on e of the four fingers and use i t when requ ired

,

and no resu lts wou ld have been poss ib le had they not b een al

l owed to use on ly th e index finger of each hand.

Sixes wi th one excep ti on were care less i n the i r work,and

many times they wou ld push any key wh ich happened to bethe easiest , unti l urged to be carefu l . Th ree o f th e E ights werefau lty in th i s respect , but rather on account of confusion resu l ting from effort a t h igh speed at the expense of correctness

,whil e

Tens were a l l anxious .to make a h igh sco re,a l l were not ice

ab ly more carefu l than the Sixes,or the average run of the Eights

.

There were vary ing degrees of interest on th e part of thesubj ec ts i n the problem i tse lf

,i n th e subj ec t ’s own progress , both

i n respect to h i s own record and h is re lat ion to ot hers . S ixeswere al l work ing on ly because they were tol d to

,and any effort

exerted was mere ly for th e sake of app robat ion . Eigh ts were

i nterested at fi rs t and glad to work,but toward the end of the

t ime became t i red of the experiment and wanted to qui t , or takeup someth i ng new ,

yet when once at wo rk they al l seemed to

put forth cons i derabl e , i f not maximum ,effort . One except i on

to the Eights i s to be c lassed w ith th e Tens . The Tens from

the fi rst were interested . There was a h igh degree of se l f ri val ry ,and of rivalry wi th each other . Each ch i ld knew h is score , andremembered i t to compare notes wi th th e others la ter . Among

the Ten boys thi s was very p ronounced ; so great was thei r des i re to exce l that al l p ract iced th e finger movement , whose s e

quence they eas i ly l ea rned in the fi rst and second day ’s work,and

when in th ei r p l ayroom one used a tab le top,two a pi ano

,one

an organ , and one drumm ed in the air. The pract i c e of th e gi rl s

was a l l confined to work in the laboratory .

DIFFERENCES BETWEEN LEVELS OF INTELLIGENCE3 5

On ly one S ix was ab le to work with the keys and smal lco lors concea led . One Eight managed i t on the second day ; five

on the th ird ; one on the fi fth ; one on th e s ixth , and two not ata l l , wh i l e a l l o f th e Tens succeeded by the beg inni ng of th eth i rd day—five on th e fi rst day , four on the second and one onthe th i rd .

The expe riment is a va luab le one for ind icat ing the ab i l i tyof an ind ividual to comprehend a s impl e exp lanat ion of detai ls ,h i s power of motor coo rdi nat ion

,capaci ty for voluntary effort

and susta ined interest . I t m ight be used as a s impl e test of intelligence if t en trial s were taken at on e s i t t i ng. When according to our resu l ts a Six shou ld comprehend the exp eriment , beab l e to use two fingers and have a record ave raging about 2 0

correct s trokes , with a moderate increase in hi s cu rve from firstto las t . An Eigh t shou ld comprehend that h e i s to use four

fingers and make some attempt to do so and reach an average of

about 50 co rrect strokes . A Ten shou l d use fou r fingers cor

rectly by th e ten th tr ia l and make an average of at l east 75 cor

rect strokes .

E xperiment 1 3 . Ink B lot Test .

As a stu dy of imaginat ion an ink b lot tes t was used , theink b lots be ing the first ten i n th e se ri es of twenty described inWh i pp l e ’s manua l of M enta l and Phys ica l Tests .

A card was shown to a subj ect to whom i t was explainedthat Thi s b lot was made by dropping a blot of ink and smeari ng i t around

.What do you th ink i t looks l ike ' O f cou rse i t

i s not exact ly l i ke anyth ing,but what does i t make you th ink

of ' ” After giv ing al l he cou ld see i n on e pos i t ion , th e ca rd waschanged unt i l i t had been in a l l fou r pos i t ions . Two m inuteswere al lowed

,b ut most subj ect s refused to look longer than a

m inute and a ha lf,and many would use l ess than on e m inute .

Thi s was part i cu l arly tru e ' of th e S ixes and least t rue of the

Tens .

Natura l ly th e expe riment does not l end i tse l f wel l to nu

mer ica l cl ass i fi cat ion,but we find

,i n a rough way , that the av

erage number of obj ects seen to a card are

3 6 ORDAHL

TABL E XXS ixes Eights Tens

Th i s shows an increas i ng superiori ty in wea l th o f imagination from the lowes t to th e h ighest grade . Reduced to terms ofper cent . of d ifference

,i t s tands

S ixes

Ei ghts

Tens 1 00

The S ixes found d ifiiculty i n s ee ing a different obj ect in anink b lo t wh o once it had suggested anyth ing to th em ,

and no

matter i n what pos i t ion thi s card was tu rned,th e p i cture was apt

to rema in th e same . The b lot was to them not so much a suggesti on of an obj ect as an actual p i cture of that obj ect . To a lessextent th i s tendency existed among the Eights

,but was hard ly

not iceab le in the Tens . An occas ional S ix enumerated obj ects

wh ich the b lot cou ld not have suggested and whi ch they cou ldnot po int ou t wh en asked to do so . To al l ch i l dren th e b lotssuggested main ly peop l e and an imals

,bu t the S ixes on ly name

the obj ect , the Eights add some descrip t ion and qual i fying te rms ,whi l e the Tens both desc rib e and attempt to i nterp ret and givea somewhat subj ect iv e character to the i r report . Thus a Six

wou l d say “ That’s a lady , here i s h er sho e and here i s h erhands .

” An E ight would state ' “ That i s a lady w it h her hai r al ltumbl ing down

,and holding her foot in her hand ,

” wh i le a fewTens wou ld say '

“ She i s a l l exci ted,and sh e is ki ck ing up her

feet and her ha i r i s tumbl i ng down and sh e is angry . Tens

were th e leas t concrete and l imit ed in thei r range of obj ects

suggested by th e p i c tu res ,such as “ dead l eaves b l owing ac ross

a rav ine,and s i tuat ions occas ional ly bei ng given instead of

defin i te wel l-known an imal s, persons or common obj ects . E ights

possessed a very l itt le of this t endency , bu t S ixes none at a l l.

S ince the work had to b e d iscontinu ed b efore th e experi

ment cou ld b e carr ied fu rther, the above account i s given ratherto ind icate th e poss ib i l i t ies of the “ ink b lot tes t” as app l i ed tothe feeb l e—minded than as an attempt to show anyth ing cone lus ive . A more careful stu dy a long th is l i ne wou ld be we l lwo rth wh i l e .

D IFFERENCES BETWEEN LEVELS OF INTELLIGENCE3 7

E xperiment 1 4. D rawing D es igns From Memory in I nvertedPos ition .

The materi a l used i n th is exp eriment consislts of twenty2 by 2 i nc-h squares d rawn on a pasteboard Card 3 by 4 i nch es .

In each square were drawn two l i nes proj ect ing inward fromth e mi ddl e of th e s ides or from the corne rs as i s shown in PlateI I I , B . Sheet s of pap er contai n i ng twenty b lank s quares

o f the same s iz e were supp lied . The subj ect was pre

sented wi th th e designs on e at a tim e wi th the fo l lowi ng i nstruct ions '

“

Study th i s des ign unt i l ~ you can see

where thes e lines wou ld b e if the square were tu rned

around unti l the bottom is where the top i s and the top i swh ere the bottom is . As soon as you can s ee where both

l ines shou ld be , and can remember,start to draw them in th i s

b lank square and I wi l l take th i s one away .

” I t wa s necessaryto say

“

tu rn around ,” otherwis e th e subj ect might conce ive th e

card as “ tu rned over and woul d conceive i t as transparent,and

draw the l ines accordingly . The subj ect was a l lowed as mucht ime as he needed . I f atten t ion appeared to wander, the experi~

menter wou ld say ' “ Just as soon as you have i t , I wi l l take thecard away .

” Each subj ect was pu t through th e s eri es of twenty

once each day for five success ive days . The resu l ts are given inTab le 2 1 . The s core i s obtained by count ing the number of

l i nes co rrect ly p laced . I t wou l d therefore b e poss ib le to scoreforty at each tria l .

TABL E ' ' I

Daily average of cor rect cases1 2 3 4 5 Gen. Av . A.D .

0 0 0 0 0 0 0

L 4

This tab le shows the average number of correct cas es for

E igh ts to be ou t of a poss ib l e 40, and for Tens out of

40 . The score i s too low to indicate any adequate comprehen

s ions on the part of ei ther the Eights or Tens . B ut th e dai ly

ave rages show the l earn ing in both cases to be rap id The

Eights ri se from on the fi rs t day to on th e fifth day .

The Tens i ncrease from to in the same t ime . Thi s i s

3 8 ORDAHL

nor a large score , s ince i t is poss ib l e fo r a subj ect to score 40by the fi fth tria l , as was actua l ly done by two of th e Tens

,and

yet the score together w i th a constant i nt e l l i gent effort on thepa rt of h igher grades wou ld p l ace the t est w ith i n the comprehension of Eights and Tens . NO norms

,however

,can be sug

gested , but i t i s qu i te l i kely better resu lts w ou l d be obtai ned i fon ly ten des igns were used and the s itt ings conti nu ed over tendays .

Thi s experimen t was calcu lated to be a test of what thewri ters have termed manipu lat ion of mental imagery

.The ex

periment has i n some means met the pu rpo s e for which i t wasdes igned . Vi sual imagery figures largely in th is p rob lem

,but

motor imagery , or s impl e cal cu lat ion with whatever imageryused may suffice .

A certa in number of persons were unab l e to te l l how theydo th i s experiment ; th ey j us t se e i t . ” B ut among the 30 feeb le

m ind‘ed cases certai n charact eristi c kinds of behav i o r were oh

served . They would se iz e upon one l in e,attempt to image i t ,

tu rn around to the“

revers ed pos i t i on,become con fus ed on the

fi rst tu rn and s l ip back to try aga in . Or they wou l d succeed ingett ing i t to the revers ed pos i t i on , then forget or be unab l e to

image wh i ch way i t shou ld s lant . Some wou ld succeed in get

t ing one l i ne reversed , bu t wou l d fo rget i ts pos i t i on before thesecond l i ne had become located . Again

,they might apparent ly

succe ed in imaging the des ign reversed and then los e the imageenti re ly before i t cou ld be drawn . Not a few woul d go a step

further,and los e on ly one l i n e in the process of construction .

A few woul d draw the l in es not revers ed but as p resented . This

i s an interes t ing ph enomenon of confus ion of imagery . .The sub

ject sees th e des ign reversed and then reverses th is image , andconsequent ly draws the des i gn as fi rs t pres ented . Two of th e

subj ects,both Ten boys

,succeeded by the end of th e fou rth day

in making a perfect score . They had di scover ed th e princ ip lethat the l in es must take oppos ite pos i t ions . They wou ld take

one glance at th e d es ign and then draw . I t appears th ey imagedthe des ign as p resen ted , th en drew the l in es according to the p rinciple i n oppos i te pos i tions .

DIFFERENCES BETWEEN L EVELS OF INTEL L IGENCE 30

Wh at ever the method final ly adopted,the in i t i a l tr i al s in

vo lve a mental process of cons i derab le complexity . The S ixes

seemed to rea l iz e what was wanted , but were to tal ly unab le tomake the essent i a l m en ta l change . The wri ter made several ind ivi dual experiment s of a s impl er sor

’t,on four differen t S ixes .

A s impl e drawing of a t ree was present ed ups ide down, w i th

the ins t ruc t ions to draw i t righ t s ide up . Invariably i t wou ld bed rawn wi th the t runk up right , bu t the b ranches wou ld s lant downat an abrup t angle. One cas e succeeded in drawing a boy with

his head on the ground and a c rude bodv on top of that , but whenh e came to the l egs . t

‘hev were out on the shou lders s lant ing

down to the ground .

I

The p roblem is.however , wi th i n the grasp of Eigh ts and

Tens,wi th the advantage deci dedly in favor of the Tens . Four

Eigh ts fai l ed a lmos t complete ly and two Tens made very poor

records .

An at temp t was made to correlate th e t ime required to draw

th e.

tw en ty des igns wi th th e accuracy of the drawing, but there

seemed to be no relat ion .

S ome seemed over- cauti ous and wou ld

take so much t ime that they became confused , others wou ld take

too l i tt let ime to make sure of the ir imagery . Anot her c l ass woul d

al low the at t ent ion to wander . he time shortened be tweenthe fi rst and las t tri a l for those who worked s teadi ly and l earnedrap id ly .

The average t ime requ ired by the Eights wasminutes Th i s was reduced to 15 minu tes for the l ast tri al .

The Tens have an average time of 2 4 5 minutes which was re

duced to 1 3 minu tes i n the last t ri a l . I t I S , howe\ er , quest ionab l e

if th e t ime e lement'has anv mean ing for th es e experiments as

conduc t ed

.

Bu t from general i ndi cat ions , i t i s p robabl e that

the most s tabl e men tal i ty wou ld requ i re the medium amount of

t im e .

E xperiment 1 5 . Compreh ens ion of Comp l ex Directions .

Th i s experimen t was conducted wi th th e expectation that

i t wou ld tes t canaci‘tv to com p rehen d and execute slight ly com

p lex di rections .

The mat eri al u sed cons i sted of ( I ) a number of

squares one i nch each way wi th a dot i n th e cen ter p rinted on

40 ORDAHL

sheets of paper ; (2 ) a number of c i rc l es one inch in d iameterwith a dot i n th e center p rinted on sheets o f paper ; (3 ) a se ri esof di rect ions

,as fo l lows .

A

Show me the center o f that square .

Show me the middl e of th e upper s ide .

Show me the low er left corner .Show me the m iddl e of th e righ t s ide .

Show me the upp er l eft corner .Show me the m iddl e of th e lower s ide .

Show me the upper righ t corner .B

D raw a l in e from the center of that square to the upperl eft corner.

D raw a l i n e from the center of that square to the midd le of the left s ide .

D raw a l i n e from the center of that square to th e lowerr ight corner.

Draw a l ine from the center of that square to the mi dd le of the upper s ide .

Draw a l i n e from the center of that square to the upper

r ight corner .D raw a l ine from the center o f that square to the m iddl eo f the r ight s ide .

C

Draw a l in e from the m idd le o f th e r ight s ide to th eupper left corner .D raw a l i ne from the lower l eft corner to th e m iddl e ofth e upper s ide .

D raw a l i ne from th e midd le of th e left s ide to th e lowerright corner .

D raw a l i ne from the upp er r ight corner to th e midd leof th e lower s ide .

Draw a l ine from th e m idd le of th e left s i de to the mi ddl e o f th e upper s ide .

D raw a l i n e from the m iddl e o f th e lower s ide to the

m idd le of th e r ight s ide .

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42 ORDAHL

l ine from the midd l e of the lower s ide to the m iddl e of the right

s i de , the subj ect wou ld d raw hi s l i ne to the center,then to

the m iddle of the righ t s i de . Th i s may have been because of a

hab i t estab l i sh ed in execu t i ng the commands of Seri es B,bu t

even so , i t i s an error caused through superfici al attent ion andinabi l i ty to con tro l more than one i dea at a time .

The errors made i n Series D were vari ous . The characteristic mistake was to i n te rchange the part of th e square mentionedwi th the part of the c i rc l e , e . g . , for di rect ion No . 2 0

,

“ Draw asquare on that c i rc l e so that the upper l eft hand corn er of the

square wi l l be a t the center of th e c i rcl e,

” th e subj ect wou ld draw

a smal l square in the upper l eft porti on of the c i rc l e .

The experiment does not at fi rst not i ce app ear to be d ifficu lt , but i t i s probab lv th e best test of th e fifteen for the control

of i deas , and comes more n ear ly to being an el ementary test in

the h igher thought p rocesses . The errors made al ready indi

ca te the di ffi cu l ty th e Tens had i n keeping ideas di s t inct andc learlv i n mind when there i s more than one . I t also i nd icates

a looseness of associati on,and reveals l i kewise an i ndispos i t ion

to mental effort , and a tendencv to be sat isfied with superfic i al

observat ion and any ki nd of an executi on . On the other hand ,

the fact that four typi ca l ly feeb le—minded ch i ld ren of th e mental

age Ten can comprehend the d i rect ions and make th e execut ions

readi ly,i nd i cates a certain indiv i dual d iff erence i n the h igher

thought processes of the feeb l e-minded . I t is qu i te possib l e that

persons may be capab l e of ex erc i s ing a re lat ive ly h igh degree of

control of the assoc iative p rocess and yet be suffi c i ent ly defect ive

i n other ways to make h im feeb le-minded .

In summariz ing the per cent . difference between the agelevel s for th e fifteen experiments

,we find in Tabl e 2 3 , that the

Ten s are I OO per cent . ,the E ights 74 per cent . and the S ixes 2 9

per cent . Since one experiment i s not d i rect ly comparab l e withanother i n numeric al terms , the i r averages are not an absolute

measu re , bu t from al l ev i dence they are a reasonab le indi cat ion of

the psychologi cal d ifference between the mental levels s tud i ed.

D IFFERENCES BETWEEN LEVEL S OF INTELLIGENCE 43

TAB L E XXI I I

Average 100 74 29

I f the experiments are grouped accord ing to mai n psy

chological process invo lved , the various l eve l s are re lated as in

dicated under the fol low ing h eadsTABL E XXIV

Ten Eight S ixSensory D iscr imi nation (Experiments 2 and 6) 100 61 15

A ttention (Exper iments 5 , 3 , 4, 1 ) 100 89 62

Memory (Experiment 11 ) 100 68 21

L earn ing (Exper iment 12 ) 100 3 6 13

J udgment (Exper iment 7 , 8 , 9 , 10) 100 79 23

Imaginati on (Experiment 13 ) 100 87 50

Reason ing (Experiment 14, 15) 100 66 0

Thi s group ing has seemed j us t ified from what cou ld be

l earned in obser vat ion of the subj ects at work . Each experi

ment involves a varying degree of comp lexi ty , bu t for th e sub

jects of thi s experiment the above named processes seem to be

the ch i ef ones i nvo lved .

In al l experimen ts attent ion i s i nvo lved and i t is p robab l e

that th i s is the psycho logical process i n w hi ch the l evel s of i n

telligence d iffer . The Sixes seem to have a consci ousness qua l i

tat ively diff erent from Eights and Tens I t may be character

ized as an incons i sten t sh i fti ng blu r . Sensory d iscr iminat ion i s

low for th i s reason . For th i s same reason memory i s feeb l e and

associ ation i rrel evant . Learn ing i s a s low process and because

44 ORDAHL

of the i r waver ing attent ion and inabi l i ty to perce ive essent ia l di f

ferences , the i r j udgment i s defect ive , and the i r imagery indefini te and l im i ted . They are p ract i ca l ly unab le to perfo rm the s im

plest p rob lem invo lvi ng reason ing. The zero sco re i n the las t

co lumn ho lds t ru e fo r all experiments where reason ing is invo lved .

There i s suffic i en t d iff erence between the score of E ights

and Tens to ind icate that th e E ights d iff er l ikew is e in a qua l i ta

t ive way from the Tens , but i t i s not so apparent from the i r gen

era l behavior in the laboratory . They fal l beh ind th e Tens in

every case involv ing a complex s i tuat ion , or where two or th ree

i deas are concerned , thus indi cat ing a d ifference in pow er of per

ceiving relat ions and making logica l assoc i at ions . Ind icat ions

are that th e E ights wou ld have app eared diff erent from the Tens

qual itat ive ly in mak ing rel evant assoc iat ions , cou ld further ex

periments have been made invo lv ing h igher thought p rocesses.

Th e Tens are super ior i n every p rocess invo lved in the fi ft een

exper iments, but they fa l l short of norma l in purpose, genu ine

interest and ab i l i ty to see the me an ing of th ings .

Sex Differences .

Data as to s ex diff erences are , of cours e , on ly of gen era l value

in th is experiment ow ing to th e l imited number of cases chosen .

However,the resu lts for th e d iff erent s exes are given , because of

what they show in regard to the ch i ldren s tudi ed . In compar ing

the sex d iff erences , the relat ionsh ip was reduced to a percental

basis in each experiment , and each age , by cons id er ing the actual

s co re of th e higher rank ing s ex as 100 and d iv id ing the low er

score by th is to get i ts per cent . Thus , in memory w ith imme

di ate reca l l t he Ten g ir l s s cored 68, the Ten boys 87 . Hence,

the boys were va lued 100 per cen t . and the gi r l 78. In experi

ments 1 1 , 14 and 15, the S ixes d id pract ica l ly noth ing, and hence

are not cons i dered in th e compari son , but are va lued at z' ro .

D IFFERENCES BETWEEN LEVELS OF INTELLIGENCE45

TABL E XXVS ix Eight

Gir ls Boys Gir ls B oys

Strength of grip 100 80 100J udgment of movemen t 100 79 100 66

S imple reacti on time . . 66 100 100 89

Tapp ing test 73 100 85 100

Attention span A 100 74 100 99

Attention span 100 82 100 74

Attention span C 100 80 100 80D isc r im ination ofg rays 92 100 93 100J udg ment of forms ,

two d imensions 86 100 100 100

J udgmen t of 95 100 79 100

J udgment of s ize 77 100 100 85J udgment of formsth ree d imens ions 77 100 69 100 10 100 B B B

11 . Memory of geometrical formsImmed iate 0 0 100

10-second 0 0 100

1-m i nute 0 0 100

Mod ified typew r iting . . 100 91 100

I nk b lot test 77 100 100

D rawin g des igns in

verted 0 100 46 100 G B

Comp rehens ion of d irect ion 85 100 100 100

88 93 94 62 98

Tab le 2 5 given t he re lat ive d ifferenc e for each age andexper imen t . U nder th e co lumns headed “

sex sup er ior i ty”

are given l et ter-s“

B” and “

G” i n d icat ing whether th e boys or

gi rls are superio r for that age and exper iment. H ere we see

that on the average for th e S ixes and Tens the boys rank h igher,

and for the Eights th e gi rl s rank h igher The greater sup eriori tyof th e Ten boys i s part ly due to the fact that th e boys average

a l i t t le h igher accord ing to the scal e of inte l l i gence than the Tengirl s

,and that one of th e Ten gi rl s was handi capp ed by a vi sual

defect . Furth er than th is there seems to be no explanation forth e sex d ifferences .

Indiv idual Variations .1

In many of th e exper iments th ere were ind ivi dua l s o f onementa l age whose resu lts resembl ed more n early those o f theh igher o r lower group . For examp l e , i f the averages o f the th irtyindiv i dual s a re a rranged i n order of rank w it h respect to th eothers i n that experiment , one of th e S ixes ranked up somewherebe tween the tenth and twen t ieth , two of the Eights around

46 ORDAHL

twenty-s econd or twenty—th i rd , and two of the Tens down among

the second ten subj ects . Bu t i t was the same ind ivi dua ls whoranked above or be low the others of h i s mental age

.One su

peri or S ix was a gi rl of exceptional ly good phys i ca l endowment,

who had the advantage of a natu ral ly good motor co—ordinat ionand freedom from phys i ca l fat igue . One of the Ei ghts whoout- ranked her fe l lows was also thus favored phys i ca l ly

,besides

be ing i nterested i n the tasks and havi ng an eagerness to succeed

which made her put forth h er best efforts . The other E ight whoexce l l ed was infin ite ly pat i en t , and made up in effort and painsfor what h e lacked in i n te l l igenc e . The two Tens who fal l bel ow do so because of an indi spos i t ion to try

,and in the case of

one an eye defect wh ich h indered in some experiments . One wasi nd iff eren t and care l ess , and the other somet imes hostil e to the

work , but when they cou l d be i nduced to put forth effort they

ranked wel l u p among the Tens . Despi t e th es e vari at ions i t i s

i n terest ing to note that i n th e experiments of a more d iff i cu lt

character i nvo lving more complex mental p rocesses,su ch as

th e comp rehens ion of d i rect ions,drawing revers ed des igns

,and

memory, the c lasses are d i s ti nct and separate , w i th no over

l ap-p ing .

Summary and Conc lus ions.

Certa i n general facts stan d out i n regard to the findings of

th e d iff erent experimen t s . Experiment 1 shows that in strengthof grip the feeb le—minded ch i ldren , wh i l e phys ical ly they maybe as strong as the average normal i nd ivi dual s of the same age ,

fal l be low because of i nabi l i ty to make th e vo lun tary effortn ecessary to produce thei r bes t resu l ts . Feeb le-minded ch i ldrenshow a dec i ded difference in the resu l ts fo r th e two hands , andare therefore not ambi dext rous as has often been suppos ed.

There i s a s l i ght d ifference in the three mental ages , Sixes ranking lowest and Tens h ighest .

Experiment 2 shows that in a test so s imp l e as j udgment

of ext en t ofmovement there i s l i tt l e di ff erence i n th e three men

tal lev e ls,the superiority of the Tens over the Eights and the

Eights over the S ixes bei ng due rather to mo re i nte l l igent be

DI FFERENCES BETWEEN LEVELS OF INTELLIGENCE47

hav ior i n fol l owing the instruc t ions of the experiment on thepart of th e upper grades of i nte l l igence .

Experiment 3 shows that a s imp le reaction experiment is,

for th e feeb le-minded , more than a s impl e voluntary p rocess ;what wou ld be marginal or reflex for normal subj ects are forthes e d i st i nct ly consc ious processes , so that react ing to a st imu lus involves ho lding severa l factors in consci ousness before re

act ing to them. The lower th e mental leve l the more th i s i s trueand the harder the task is .

In Experiment 4, th e cu rve of tapp ing shows the greatestlack of volunta ry effort on th e part of the S ixes

,and l east on the

part of the Tens , who are sti l l -s lower and show a d ifferent . curve

from what we wou ld expect for normals . Pound ing the k ey andwaste of energy by the S ixes ev idences the i r lack of judgment

Experiment 5, whi ch i s a real atten t ion experiment , showsmore d ifference in the resu lts of th e three l eve ls

,the score be

ing proport iona l to the mental age , and the more comp lex thes eries , the greater the di fference in the resul ts of the threegroups . Here we find a d iffe rence in the power of comprehendi ng the demands of the p rob l em and adj ust ing to th em ,

and a

diff erence in attent ion span varying d i rect ly with the menta lage , th e S ixes bei ng the weakest .

Experiment 6,d iscr im inat ion of grays , s eems to i ndi cate that

as far as br ightness d i scr im inat ion i tse l f i s concerned the threel eve ls are about equa l

,th e d ifferenc es that th e resu lts show being

du e -to th e fact that th e lower leve ls are somet imes care less inmak ing the i r dec isions . Any variat i on is rather a matte r of atten t ion than of

‘

discriminib ility.

Exper iments 7 and 8 show that an exper iment shou ld be dif

ficult enough to requ ire some effort on the part of feeb le-mindedsubj ects

,for they are too eas i ly sat i sfi ed wi th moderate success ;

i f they get th ings “ a lmost r ight ,” they cease to try when per

fection wou l d b e poss ib l e w ith a l i t t l e extra effo rt . Exp eriment8 was too d ifficu lt for th e S ixes because there was too much toho ld in consc iousness at once and too much susta ined attent iondemanded . Experiment 9 , the j udgment of s ize and form ,

i s notan immediate process . I t is an association of imagery of d iff erent

48 ORDAHL

sense realms , which i s not spontaneous,bu t construct ive , and

involves some reason ing. Hence the greater difiiculty for th elower l evels of in te l l igence .

Exper iment I O on the j udgment of forms of th ree d imens ionsis a bet te r test for compar ing the th ree leve ls of inte l l igence thanthe p rec ed ing tes ts because of i ts complexity . I t is a severetask for the S ixes , eas i e r for the E ights and least diffi cu l t forTens

Exp e riment I I on the memory of complex geometrica l fo rmsinvo lves so much d i scr im i nation o f diff erence in fo rm and so muchattent ion that i t is more than a tes t o f retent iveness . In fact

,it

i s d i ffi cu l t to dete rm ine in how far demands made on these h ighermenta l p roc ess es h inder i t from bei ng a memory exper iment forth e S ixes , fo r the d i st inguish i ng of th e forms thems e lves i s analmost impos s ib le task .

Experiment 12 on the mod i fied typewri t ing vari es in difficu l ty w ith the di ffer ent mental ages , both as to speed , accu racy ,and rate of learning. This difference was due to th e greater

un i ty of consc iousness of the h igher leve ls , s ince for them somefactors were from the s tart margina l , wh i l e for a S ix , and to al esse r degree for an Eight , all fact ors were apt to be of equal val u ein consciousness , with a resu l t ing confus ion . Riva l ry was characteristic of the Ten s , Eights showed l i t t l e riva lry , but a p leasu re in a good record , Wh i le S ixes worked because they had to ,but enj oyed the approbat ion of the experimenter .

E xp eriment 13 , the ink b lot tes t , gave h igher resu lts in pro

portion to the hei gh t i n inte l l igence . Th is i s du e to the greaterweal th of imagery the brighter subj ec ts pos sess ed , ow ing to theircapacity for tak ing in more ideas wi th a resu l t ing richer mental

content than lower grades .

Experiment I4, on comp rehending d i rections , shows a de

ci ded lack of reasoning ab i l i ty on the pa rt of th e S ixes . They

have difficu lty in ho ldi ng deta i l s in mind long enough to relateand compa re them. I t means a degree and du ration of att ent i on and vo luntary effort not poss ib l e fo r th e S ixes

,d ifficul t for

Eigh ts , but re lat ively easy for the Tens .

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50 ORDAHL

The lower the l eve l of inte l l igence,the more the sub

j cet i s lack ing in reasonab l eness and good j udgment in p erforming h i s work .

(8) The feeb le-m inded have pronounced ind iv idua l ity , bu t

are deficient in p ersona l i ty ; that i s , thei r ind ividua l characteris

t ics are very p ronounced , bu t the i r tra its and pecu l i ari t ies are not

c losely un ifi ed into a personal ity . A S ix hard ly regards h imsel f

as an indiv idua l , an Eight makes superfic i al personal d i st inctions ,W h i le even for a Ten se lf-rea lizat ion does not become a rea lity .