- Email: [email protected]
Tactual discrimination thresholds for shape and texture in young children
Tactual
Discrimination
Thresholds for Shape in Young Children’
and
Texture
Discrimination thresholds for shnpc and test,ure w-ore oht:liul~tl in kintlcrgarten and third-grade children. Pairs of shapes (ellipses) and testurrs (sandpaper patches) were prwentcd to the children who judgwl wllcthclr the stimuli were the same or different from ench otlrcr. The stimuli were prcsented in two different embedding contests. The trst~ure pairs cowred the entire perceptual field or were ronfincd to the top of a rotAantS shape. The shape pairs were presented as plain Masonite> cut-outs or wcrr rovcrrd with a constant grit sandpaper. There was a significant increase Ctll npc in sensitivity to texture but not to shape. HOWW~I~, the> variabi1it.v in wnsilivit> to shape did show a decrease xit,h axe. ‘The rougher stimuli w(w cnsicr 111 discriminate than thr smooth stimuli 11.v I)oth aws unrlcr x11 renditions in texture discriminations. Rrsult,!: of rcplicxtion studies \vith n~lulis nnrl l,lin(l children showed no overall significant differences from tllc> norm:~ll~~ tkhicvi third graders.
‘file present study is 2 psyc~l~ophysical inr-est,igation of t.he development (II active tactual pcrceldion in children. In spite of t,he fact that the empiricist, point of view in perception has suggested that. visual pcrception is based on prior development of txtud pcrccption (Hochbcrg. 1964)) little spstcmntic research ha:: bcell done. Two esccptions are the work of Zinchc>nko and his volleagucs (Zinchenko ant1 Ruzskaya, 1960) and that of Pin.get :tnd Inhclclcr (1956). These inxd,igators haw studied the discriminat’ion abilities nncl exploration patterns of preschool and clemc~nt,:vg ~cl~ool children. Generally speaking, as one would eqwct, the children improTe in their ability t’o recognize objects tactually, and they become more syst’ematic in their exploratory behavior. ’ This rezcarcb was conducted under Public Health Scrvil,c F~~llowship (No. 5-PlMH-20, 263-03) from the National Institulr of Mrnt.:~l Hwlth in lwtia.1 fulfillmr~nl of tllr requirements for the dortornl drgrec. Thr auihor ic in(tehted to 1)r. Hnbcrt IA. Pick, Jr. and Dr. Anne D. Pick for their adviw and critical reading of thr manuscript. The help and cooperation of Dr. John Ii. Hanson, supcrintendcnl, Fridlel Public School System, Mr. Ray Hable, principal, Hayes Elementary School, Mr. Norman Kaplan, executive director, Foundation for the Junior Blind, and tht, teachers and counselors involved is greatly acknowledged.
‘F.ACTUAI.
DISCRIYI?;hTION
THRESHOLDS
537
‘i‘.~~!‘~~:,Ii.
l)ISCR.IMIN,iTIO~
TIIRESHOLD.’
54( 1
(‘1 \‘IIII.\
II.
~.I,ISF.II
determine whether the mere presence of :I dirtincti\.c dral~t: or tcsturca would impair the discriminnbility of ksturcs ant1 shapc~ rcqc~!~ti\.c~ly. Each S participated in only one of the four conditions. The S fxed a 30 X 24 inch SCITCII :tu(l ~~cachc~l hi:: II:WCI through :I rurtaincd S1/z X 6 inch hole to fccxlkwo stimuli. The piilnuli w~rc mountcci on a turntable 30 inches in diameter. Enrh st:~ndnrtl W:W fl:mkcd by t,wo clifferent comparison stimuli. but a hand gnidc rcstrictcd S’s liaml mm-t’merits such that he could fecsl only one pair of stimllli ith: st :~nclartl :ml one comparison) at. a time. The stimuli ill ~arh IxCr ww approxima tel! I,& inch apart,, cscq-k in the Texture condition whc~ :t l!j incll st,ril) 01 lL%inch Masonitc~ separated the two adjacent tcsturc~~. Just to the left. of the curtained hole, on S’s side of the ,~;crcon, was :I 5 x 6 I< 1’ ‘G itlcall transparent plastic bos into which marbles (‘l,cinforc’c,lucllt~~ WK~ (If,liverecl by a Gerbrands marble dispenser cont,rolled by :I foot.ktcll. There were four turntahlcs corresponding to the four stimulus r*ondit.ionF. Procedure. The S n-as scntcd facing the Fcrccn after being introducctl to a “Feelp Game” and picking n prize for which to work. I-Iis right hand c~stcndctl through the curtailled hole in the .WWW to fcvl tn-o htimuli. FTC was told that hr woultl hav(x to feel t,li~ two things anal y;:Iy if t,llcy w(~i’(’ the same or different, from cbach other. :A:: an example, R guided S’S hanc I over the pair with the great& difference (no. 7 or 7’ compnrihon stimulus in Fig. 1) and told him that these two thin gs were different. This procedure was rcpcated for the identity pair (the two stnn~lnrds) with S being told t’hat the two things were the s;tn~. Thea t’raining plla~ thcxll began. The S was presented with two cs:mplcs of diffcrvtlt lj:lir+ ino. 7 and 7’ comparison st,irnuli in Fig. I) and the itlentity pnir :u~d told that it was now his t,urn to tell E if the two things n’erc’ the sam(~ or diff’crcnt. Whencvcr he ~1:: correct,, S received a mnrblc whirl1 hc co111dlxtcr tut.11 in for his prize. In :atldition, verbal reinforccmcnt uw givczn for corr(~ct~ (“That’s right”) and incorrect, responses (“So, tho$c two things :WC’the> same’! or “No! those two things are differcilt”I, hftcxr S Iin matlc (*ifflit consecutive correct responses (four “same” and four “ciifPcrent.” randomly presented) within a masimum of 40 trials. the testing 1~1~~s~ hrg:~t~ without any brt~& in the prorcdurc. .Alq S not illc,etinK rritc~rioii in ih~t t,raining phn~ wa:: replaced.” Testing occurred in three blocks of i’our trial? each ill :L concentrila series with the two most similar :intl two most tliffcrcnt, rc,ni:lining pair> being presented in each block (i.e., 6, I’, 1. 6’, then 2’, 5; 5’. 2, t,hell 3, 3’, 3, 4’). Each stimulus t,cst, pair was presented only onre to each ,q.
‘I’hv cwncrcntric ordrr nf prct;entat.ion was used tn :I,VOI~ hulldmg up :t rc~sponses;ct ill which S might, give all %ame” or all “different” responses. Positive reinforcement, was given on every t’es:t trial. Bctwecn each block of four test trials, thcrcb wcrc two trials given with the trainin,g pairs (the> illentity pair and no. 7 or 7’). Only on these trials was positive reinforcetrltxnt contingent on the correct rcspon~. This contjingency was necessary 10 n~oid aily response set \vl-ltich may h:~ue been reinforced unwitting]! tluring the test, trial.<. If S mnclc~tllrec ~~t~rorsin tllcl six cont,ingt:nt t,riaIs;. IIP w:ts replaced.Z The E recorded correct and incorrect responses during t,raining and thca qpccific response (“same” or “different”) to each stimulus pair in the tc>stiljg phase. In addition, E made observations about the relative amount ol’ time spent feeling the shape and the tcsture of the stimuli and th(s 1txLnner in which S explored the stimuli (e.g., grasping. tracing, fcclling c,:lch Ptimulus separately or both together). Tn summary, kinclergnrtcn and third-grade uhildrrn cliscriminatecl :Imong a series of pairs of textures or shapes. The textures were cithrr l)rc~r;cntcd without sh:1pe or on a eonstnnt shape; the shapes, eit.her unttxt,ured or covered with a const.nnt teskrre. There were 10 hogs and 10 girls assign4 to c:~rh of the conditions at’ clach age level. RESULTS Tl~rcsl~olds for each S ‘\l-ere calculated on the basis of the “samccliffcrent” judgmclnts he had made. The particular scores were based on the numbers assigned to the stimulus pairs. The thresholcl was de&d :W the midpoint of the interval of uncert,ainty (I.U.) which in turn was flt~fiiierl :1s the siztl of the range below which S gave consistent “F;am(” 1~1~~1~on~c’s and :above which hc gave consistent “differrnt” rceponsc~. Thus. :III ,< who mndr~ rcqonscs “snmc-s:unc-rliffcr~~~t-diff~r~~~t~-~liffere~~~-~liff~~~cit,t ** on pairs 1-6, rcqcetivcly isee Fig. 1) would obtain n threshold of 2.5 with au 1.X:. of 1. The thrrshold was a measure of discriminnbilit? hclnsitivity, while the size of the I.U. was a measUre of precision 01’ x.:~ri:ll)ility. For each X, two discrimination thresholds and two corrtaqxmtling 1.V.s were determined: one threshold and one I.U. for the roug11 4imuli :und one t~hreshold and one I.U. for the smooth for those Ss in thck 1Iastllrt> c>onditions, and corresponding mc,asurcR for the round and sliltl -I imllli ill the shape conditJions. Te.ctwt~. The mean thresholds for texture are illustrated graphically ilr Fig. 2. An analysis of variance revealed a significant, effect of Age (F = -5.61; df = 1, 72; p < .05), wit,h third graders obtaining lower threshold:: TIMID kintlcrgarteners. In addition, rough stimuli were much easier t.n ~liwt.iolimtr thnn smnrd II CF -- 176.23; cl! - 1 1 72: 17C- .Ml\ Sgnifirnnl.
An analysis Ol \.:triaurcb of the 1.ti.e ngaill rc~vc~:lhd 9, highly signifiwrll effect of Roughness (F = 12.66; df = 1, 72; p < .Ol). The relat,ire inlprecision of third grade boys on the smooth stimuli in the ShapedTexture condition was the main contributing factor in the following two internctione: Age X Roughness iF = 7.58; df ~7 1. 72; p < .01‘1 x11(1SPY x Roughmw (F .- .3.X0: 11i ~~~I. 72: ,I’ C’ .ln~.
‘l%tfi k’s ohscrv:~tions of Ss’ behavior sl~owctl the girls more often eliiplaying succcssivc exploration (one stimulus nt a time) in both of thv tcsturc condition?, while boys used simultaneous explor:lt,ion iboth stimuli :tt OIIW~ more frequently (x’ = 4.02; c!f = 1 ; p < .05). This diffcrenrc ill Ftr:ittyy w:w not correlated with threshold in tlw hop, hut in the girls, wvrtwiw csploration n-as significantly :i+ociated with lower t l~rc~sl~oItls 1I‘,,11 .33 ; p < .05) To descrilw the discriminnbility of c:wIl intlivitlwtl Iwir of si.inn~Ii ~‘(JI’
analysis of the I.(..>, however, did re\-eal a ul:Gu effect ut’ =\gtt t b’ 5.77 : df = 1, 72; p < .OS), wit,11 t’hird graders being more precise than kindergartcners. A significant Condition X Scs >< For111 intcrnctioll (F’ ~;~6.73; df = 1: 72; p < .05) showed that with th(s round stimuli otlly, i.1~ girl> had sniallcr 1.U.s in the Shape cunditioll. nhjlc tlic l~oy- 11:tfl ~III;LIIC~I intervals in the Tcsturcd-Shal)e coutlition. Fig. 4 illwtlxt(~~ th(, IIKTI~ 1.u. for
cad1
$0111).
-
BOfS-ROUND
STIMULI
W
GIRLS-ROUkD
Silh~lltl
l
-0
Q--O
BOYS-SLIM
ST!MUI.I
GIRLS-SL’N
STI,%UtI
1
OLL SHAPE
TEXTURED-SHAPE
SHAPE
KINDERGARTEN
FIG. 4. Meun
1.lJ.a
of .s:hapc
thwshohis
TEXTURED-SHAPE
THIRD
for kiucl~rga~%a
GRADE
aud third-sg:~lv
23s II, t \\(I
(,antest conditionr. 811 Ss used
successive
movwu~uts
o\.t’~’
tltcs
1 \vu
st,imuli
irl tllo
&])I~
conditions, and most employed :t nlnrlil)ul:~tol~~ movement r:Lther than :I I~c:lat~ionship (racing or grasping movement. Therca ~\yrtl IIO significalkt X~HI :IIIV of the discrirnin:~-tbetween any of these behaviorzl ohser~-sti~nl~ tion measures &t.aine4 I.
‘~‘IH-]l.~~~~llopl~~sicalfunction shown m Fig. 5 revealed no consistent ag:1’ clifference. Again, this observation i9 in agreernrallt with the analysis OI T~:trinnce of thP thlcslmld nleasur(x
FIG. 5. Percentage sl~apr 17onditions.
of rhildren
responding
“different”
to each stimulus pair in l)oth
DISCUSSION
T11r :mticipnte(l intci4c~rmce efftbct5 of tlic c~inlxxl~liug contest did not OW~~I~for cithctr of the dimcnsion~. It had bec~l IlypotlxAzed that third ,~t~:t~I~frs woultl 1x2 ilnlxtiwcl ill thck texture judgnients hy :I coiis;tniit clis1 irlrtivcl sli:II’e; howvcve~~, only girls showed this tcndcncy. In addition,
girl,+ of hot11 ages showed t’his trend; thus there was no age interaction with tllc condition :te hypotheeizcd. In the shape thrcsholdq rather thn11 :Ln iinpnirm~ni, tmliere nppe:mxl to be a slight facilibtion rffcct, of tlkcb c~nlhc~l(li~~gcsontc‘st whc~ the const:)nt testmurcxt~nhanccrl the shapr judg-
Discrimination
Thresholds for Shape in Young Children’
and
Texture
Discrimination thresholds for shnpc and test,ure w-ore oht:liul~tl in kintlcrgarten and third-grade children. Pairs of shapes (ellipses) and testurrs (sandpaper patches) were prwentcd to the children who judgwl wllcthclr the stimuli were the same or different from ench otlrcr. The stimuli were prcsented in two different embedding contests. The trst~ure pairs cowred the entire perceptual field or were ronfincd to the top of a rotAantS shape. The shape pairs were presented as plain Masonite> cut-outs or wcrr rovcrrd with a constant grit sandpaper. There was a significant increase Ctll npc in sensitivity to texture but not to shape. HOWW~I~, the> variabi1it.v in wnsilivit> to shape did show a decrease xit,h axe. ‘The rougher stimuli w(w cnsicr 111 discriminate than thr smooth stimuli 11.v I)oth aws unrlcr x11 renditions in texture discriminations. Rrsult,!: of rcplicxtion studies \vith n~lulis nnrl l,lin(l children showed no overall significant differences from tllc> norm:~ll~~ tkhicvi third graders.
‘file present study is 2 psyc~l~ophysical inr-est,igation of t.he development (II active tactual pcrceldion in children. In spite of t,he fact that the empiricist, point of view in perception has suggested that. visual pcrception is based on prior development of txtud pcrccption (Hochbcrg. 1964)) little spstcmntic research ha:: bcell done. Two esccptions are the work of Zinchc>nko and his volleagucs (Zinchenko ant1 Ruzskaya, 1960) and that of Pin.get :tnd Inhclclcr (1956). These inxd,igators haw studied the discriminat’ion abilities nncl exploration patterns of preschool and clemc~nt,:vg ~cl~ool children. Generally speaking, as one would eqwct, the children improTe in their ability t’o recognize objects tactually, and they become more syst’ematic in their exploratory behavior. ’ This rezcarcb was conducted under Public Health Scrvil,c F~~llowship (No. 5-PlMH-20, 263-03) from the National Institulr of Mrnt.:~l Hwlth in lwtia.1 fulfillmr~nl of tllr requirements for the dortornl drgrec. Thr auihor ic in(tehted to 1)r. Hnbcrt IA. Pick, Jr. and Dr. Anne D. Pick for their adviw and critical reading of thr manuscript. The help and cooperation of Dr. John Ii. Hanson, supcrintendcnl, Fridlel Public School System, Mr. Ray Hable, principal, Hayes Elementary School, Mr. Norman Kaplan, executive director, Foundation for the Junior Blind, and tht, teachers and counselors involved is greatly acknowledged.
‘F.ACTUAI.
DISCRIYI?;hTION
THRESHOLDS
537
‘i‘.~~!‘~~:,Ii.
l)ISCR.IMIN,iTIO~
TIIRESHOLD.’
54( 1
(‘1 \‘IIII.\
II.
~.I,ISF.II
determine whether the mere presence of :I dirtincti\.c dral~t: or tcsturca would impair the discriminnbility of ksturcs ant1 shapc~ rcqc~!~ti\.c~ly. Each S participated in only one of the four conditions. The S fxed a 30 X 24 inch SCITCII :tu(l ~~cachc~l hi:: II:WCI through :I rurtaincd S1/z X 6 inch hole to fccxlkwo stimuli. The piilnuli w~rc mountcci on a turntable 30 inches in diameter. Enrh st:~ndnrtl W:W fl:mkcd by t,wo clifferent comparison stimuli. but a hand gnidc rcstrictcd S’s liaml mm-t’merits such that he could fecsl only one pair of stimllli ith: st :~nclartl :ml one comparison) at. a time. The stimuli ill ~arh IxCr ww approxima tel! I,& inch apart,, cscq-k in the Texture condition whc~ :t l!j incll st,ril) 01 lL%inch Masonitc~ separated the two adjacent tcsturc~~. Just to the left. of the curtained hole, on S’s side of the ,~;crcon, was :I 5 x 6 I< 1’ ‘G itlcall transparent plastic bos into which marbles (‘l,cinforc’c,lucllt~~ WK~ (If,liverecl by a Gerbrands marble dispenser cont,rolled by :I foot.ktcll. There were four turntahlcs corresponding to the four stimulus r*ondit.ionF. Procedure. The S n-as scntcd facing the Fcrccn after being introducctl to a “Feelp Game” and picking n prize for which to work. I-Iis right hand c~stcndctl through the curtailled hole in the .WWW to fcvl tn-o htimuli. FTC was told that hr woultl hav(x to feel t,li~ two things anal y;:Iy if t,llcy w(~i’(’ the same or different, from cbach other. :A:: an example, R guided S’S hanc I over the pair with the great& difference (no. 7 or 7’ compnrihon stimulus in Fig. 1) and told him that these two thin gs were different. This procedure was rcpcated for the identity pair (the two stnn~lnrds) with S being told t’hat the two things were the s;tn~. Thea t’raining plla~ thcxll began. The S was presented with two cs:mplcs of diffcrvtlt lj:lir+ ino. 7 and 7’ comparison st,irnuli in Fig. I) and the itlentity pnir :u~d told that it was now his t,urn to tell E if the two things n’erc’ the sam(~ or diff’crcnt. Whencvcr he ~1:: correct,, S received a mnrblc whirl1 hc co111dlxtcr tut.11 in for his prize. In :atldition, verbal reinforccmcnt uw givczn for corr(~ct~ (“That’s right”) and incorrect, responses (“So, tho$c two things :WC’the> same’! or “No! those two things are differcilt”I, hftcxr S Iin matlc (*ifflit consecutive correct responses (four “same” and four “ciifPcrent.” randomly presented) within a masimum of 40 trials. the testing 1~1~~s~ hrg:~t~ without any brt~& in the prorcdurc. .Alq S not illc,etinK rritc~rioii in ih~t t,raining phn~ wa:: replaced.” Testing occurred in three blocks of i’our trial? each ill :L concentrila series with the two most similar :intl two most tliffcrcnt, rc,ni:lining pair> being presented in each block (i.e., 6, I’, 1. 6’, then 2’, 5; 5’. 2, t,hell 3, 3’, 3, 4’). Each stimulus t,cst, pair was presented only onre to each ,q.
‘I’hv cwncrcntric ordrr nf prct;entat.ion was used tn :I,VOI~ hulldmg up :t rc~sponses;ct ill which S might, give all %ame” or all “different” responses. Positive reinforcement, was given on every t’es:t trial. Bctwecn each block of four test trials, thcrcb wcrc two trials given with the trainin,g pairs (the> illentity pair and no. 7 or 7’). Only on these trials was positive reinforcetrltxnt contingent on the correct rcspon~. This contjingency was necessary 10 n~oid aily response set \vl-ltich may h:~ue been reinforced unwitting]! tluring the test, trial.<. If S mnclc~tllrec ~~t~rorsin tllcl six cont,ingt:nt t,riaIs;. IIP w:ts replaced.Z The E recorded correct and incorrect responses during t,raining and thca qpccific response (“same” or “different”) to each stimulus pair in the tc>stiljg phase. In addition, E made observations about the relative amount ol’ time spent feeling the shape and the tcsture of the stimuli and th(s 1txLnner in which S explored the stimuli (e.g., grasping. tracing, fcclling c,:lch Ptimulus separately or both together). Tn summary, kinclergnrtcn and third-grade uhildrrn cliscriminatecl :Imong a series of pairs of textures or shapes. The textures were cithrr l)rc~r;cntcd without sh:1pe or on a eonstnnt shape; the shapes, eit.her unttxt,ured or covered with a const.nnt teskrre. There were 10 hogs and 10 girls assign4 to c:~rh of the conditions at’ clach age level. RESULTS Tl~rcsl~olds for each S ‘\l-ere calculated on the basis of the “samccliffcrent” judgmclnts he had made. The particular scores were based on the numbers assigned to the stimulus pairs. The thresholcl was de&d :W the midpoint of the interval of uncert,ainty (I.U.) which in turn was flt~fiiierl :1s the siztl of the range below which S gave consistent “F;am(” 1~1~~1~on~c’s and :above which hc gave consistent “differrnt” rceponsc~. Thus. :III ,< who mndr~ rcqonscs “snmc-s:unc-rliffcr~~~t-diff~r~~~t~-~liffere~~~-~liff~~~cit,t ** on pairs 1-6, rcqcetivcly isee Fig. 1) would obtain n threshold of 2.5 with au 1.X:. of 1. The thrrshold was a measure of discriminnbilit? hclnsitivity, while the size of the I.U. was a measUre of precision 01’ x.:~ri:ll)ility. For each X, two discrimination thresholds and two corrtaqxmtling 1.V.s were determined: one threshold and one I.U. for the roug11 4imuli :und one t~hreshold and one I.U. for the smooth for those Ss in thck 1Iastllrt> c>onditions, and corresponding mc,asurcR for the round and sliltl -I imllli ill the shape conditJions. Te.ctwt~. The mean thresholds for texture are illustrated graphically ilr Fig. 2. An analysis of variance revealed a significant, effect of Age (F = -5.61; df = 1, 72; p < .05), wit,h third graders obtaining lower threshold:: TIMID kintlcrgarteners. In addition, rough stimuli were much easier t.n ~liwt.iolimtr thnn smnrd II CF -- 176.23; cl! - 1 1 72: 17C- .Ml\ Sgnifirnnl.
An analysis Ol \.:triaurcb of the 1.ti.e ngaill rc~vc~:lhd 9, highly signifiwrll effect of Roughness (F = 12.66; df = 1, 72; p < .Ol). The relat,ire inlprecision of third grade boys on the smooth stimuli in the ShapedTexture condition was the main contributing factor in the following two internctione: Age X Roughness iF = 7.58; df ~7 1. 72; p < .01‘1 x11(1SPY x Roughmw (F .- .3.X0: 11i ~~~I. 72: ,I’ C’ .ln~.
‘l%tfi k’s ohscrv:~tions of Ss’ behavior sl~owctl the girls more often eliiplaying succcssivc exploration (one stimulus nt a time) in both of thv tcsturc condition?, while boys used simultaneous explor:lt,ion iboth stimuli :tt OIIW~ more frequently (x’ = 4.02; c!f = 1 ; p < .05). This diffcrenrc ill Ftr:ittyy w:w not correlated with threshold in tlw hop, hut in the girls, wvrtwiw csploration n-as significantly :i+ociated with lower t l~rc~sl~oItls 1I‘,,11 .33 ; p < .05) To descrilw the discriminnbility of c:wIl intlivitlwtl Iwir of si.inn~Ii ~‘(JI’
analysis of the I.(..>, however, did re\-eal a ul:Gu effect ut’ =\gtt t b’ 5.77 : df = 1, 72; p < .OS), wit,11 t’hird graders being more precise than kindergartcners. A significant Condition X Scs >< For111 intcrnctioll (F’ ~;~6.73; df = 1: 72; p < .05) showed that with th(s round stimuli otlly, i.1~ girl> had sniallcr 1.U.s in the Shape cunditioll. nhjlc tlic l~oy- 11:tfl ~III;LIIC~I intervals in the Tcsturcd-Shal)e coutlition. Fig. 4 illwtlxt(~~ th(, IIKTI~ 1.u. for
cad1
$0111).
-
BOfS-ROUND
STIMULI
W
GIRLS-ROUkD
Silh~lltl
l
-0
Q--O
BOYS-SLIM
ST!MUI.I
GIRLS-SL’N
STI,%UtI
1
OLL SHAPE
TEXTURED-SHAPE
SHAPE
KINDERGARTEN
FIG. 4. Meun
1.lJ.a
of .s:hapc
thwshohis
TEXTURED-SHAPE
THIRD
for kiucl~rga~%a
GRADE
aud third-sg:~lv
23s II, t \\(I
(,antest conditionr. 811 Ss used
successive
movwu~uts
o\.t’~’
tltcs
1 \vu
st,imuli
irl tllo
&])I~
conditions, and most employed :t nlnrlil)ul:~tol~~ movement r:Lther than :I I~c:lat~ionship (racing or grasping movement. Therca ~\yrtl IIO significalkt X~HI :IIIV of the discrirnin:~-tbetween any of these behaviorzl ohser~-sti~nl~ tion measures &t.aine4 I.
‘~‘IH-]l.~~~~llopl~~sicalfunction shown m Fig. 5 revealed no consistent ag:1’ clifference. Again, this observation i9 in agreernrallt with the analysis OI T~:trinnce of thP thlcslmld nleasur(x
FIG. 5. Percentage sl~apr 17onditions.
of rhildren
responding
“different”
to each stimulus pair in l)oth
DISCUSSION
T11r :mticipnte(l intci4c~rmce efftbct5 of tlic c~inlxxl~liug contest did not OW~~I~for cithctr of the dimcnsion~. It had bec~l IlypotlxAzed that third ,~t~:t~I~frs woultl 1x2 ilnlxtiwcl ill thck texture judgnients hy :I coiis;tniit clis1 irlrtivcl sli:II’e; howvcve~~, only girls showed this tcndcncy. In addition,
girl,+ of hot11 ages showed t’his trend; thus there was no age interaction with tllc condition :te hypotheeizcd. In the shape thrcsholdq rather thn11 :Ln iinpnirm~ni, tmliere nppe:mxl to be a slight facilibtion rffcct, of tlkcb c~nlhc~l(li~~gcsontc‘st whc~ the const:)nt testmurcxt~nhanccrl the shapr judg-