Reactivatin.;Preschool children 'sMemo r y for the Lcc atLcn of Hidden Obje cts
by
RobertB. Gauthier,B. A.,B. Ed., M.Ed.
At.h es issubmittedto the Sc ho ol of Graduate
s
tudies in partia l fulfil lment of th e requirementstor thedegree of Haster of Science
Departmentof Psycho lo g y Memoria l Un i v e r sit yof Ne wtcun cland
19 93
st.
John 's Newfcundland1+1
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Abstract
Thereis little cesear ch regarding theamount cr informationthat t.hr eee yea r vol d children canr etain and the le n gt h of lime that they can retain it. l r,a task in wh i ch three-year-oldsretained the locationsat hid de nob j e c ts, subjects were giv ena r eacttvacion treat men t to det ermine if the reminderwoul1 facil Lt ate re c a l l . Anadditional question wes whether havlng input into whereob jec ts we r e hiddenwo u l d tacrtrtat.e recall.
Ninetych il d re n lear ned the location of 16 objects hi ddenin a room. One-half of thech ild r en det ermined whi ch object to hide in each of the p r ees eIe cte d locations (s e lf-g en"r a t e dco n d ition), and the experime n te rdeter mi ne dwh i ch objectto hideat each lo ca t i on for the remaining children
(experimenter -g e ne ratedcondition). For boththe s e If- andexp eri mente r-genera tedconditions, one-thi rd of the childrenwere visitedthree weeks after acquisttLcn at whichtime theysa w the16 objects Lr eactivetrcn treatment). Another one-thi rd were returned tot he expe rime ntal roombut did not see th e obje ctn (pa r tial-r ea c tiva tiontreatmene ) , 'rho remain:'ng one - thia:dof th echdl dr en we r e visited againon ly at final testing (control tre a t men t ) , All subjects we r e tested
i i
for recall of the 16object-locationpa ir ing s';weeks after initial le ar mnq. Resultsshowed no sil}r.:.fican t dLfference s due to reactivationor generation cond ittcns.
iii
Table of cc n t ent s
Page
1I.BSTR1I.C'l'.. ..•... • •.••... .•... ... . . . .• •. i1 LISTOFT1I.BLES•..•.••••. ... ..• ...•• ... ... . 1I.CKNOWLEOGHENTS.. .• •...•.... . .... .. .. .. .. ... vi
INTRODUCTI ON.••. •.••.. . . . ...• • . • •.•.. .. . 1.1 Reacti vation.• . . .. ••. • . . . .•.••••. . • •. 1.2 Self- vers u s Experiment erGene ra t ed
Le a r nin t;l... . . .... ... .. ... 11 1.3 Memory forHidden Object Loc ati on s.. . :!2 1.4 Present Re s e arc h.. ... .. .. 27 II METHOD... . . . •••. •.
III RESULTS•.. ... .. . . .•... . . . ..
29 J6
IV DI~.."SSION. .. 40
REFERENCES. ... . .. ... ... . ... . ... S3 TABLES. . . ... . .. . . .. ... .. . ... . . 60
iv
Table 1.
Table 2.
Table 3.
List of Tables
Page
Analysis of va rtaoce on acquisition d~ta.... . . .. . . ... . . . ... . .. . . .... 60 Analysi s .:If cov a ri anc e on long-term
retention data... . ... 61
Mean errors for eachtr e a t me nt condition••.. .. ... . ••.... .••, ... •,... 62 Table 4. Mean errors for the Self- and
Experimenter-Generated Condi tions employedin the Newman-Keuls Test. 63
ACKNOWLEDGMENTS
I am grateful to the24 daycare ce n t r e s and preschools whichso graciously allowedme to interrupt theirdail yschedules to permit testin gof thechildren.
A specialth an k -you is givento the children who partici p at e d.
I wou l d liketo thank Dr. Jack Strawbridgetor his criti quesand contributions to this thesis. !would alsolik e toth an k Dr. MikeRabino:fitz .
This thesisis dedicated to my wife, Beverley, wit h o u t whose lov e , encouragement and supp o r t itwould ne ve r havebeencomplet ed.
vi
React: vati n g Preschool Ch il d r e n ' s Memory for the Loc a ti on of Hidden Objects
Research hasgt:ownin thearea of lony-t er m retention of in f o r ma t ionby infants, school-agechildren and adults (e.g., Brainerd ,Kingma , SoHowe, 19B5;
DeLoache , 19B6; HoweSoBrainerd, 1989 ; Rovee- Cc llier1io
Hayne, 1987). .However, the r eis littl e eviden ce regarding the amount of infor ma t ion thatpr eschoo l e r s can ret ai n and thele n gth of ti methat they car, re t a i'l it Intest s of lon g -te rmreten t i on , re s ear c h ers have fou n d that reactivating informat ion durin ga ret ent.Lcn interval is effectivein faci litating re c a ll ininf ants (e. g., Rcv ee-c o ltLerSoHay n e, 1987) and sc ho olage chiId r e n (e .g. ,Hoving£:,Ch o i, 1972;Hoving,Coates, Ber tu c c i , s Riccio,1972). One issue in te st s .:f lon g- termre tentioniswhethe r reac t iva ti on of the in fo rma ti on lear ne dinthe ac qu dsitLcn sta ge will facil it at e re c al l in pr eschoo l chil d r e n . As vell,it is not knownwhe ther a fullre a c ti v a tio n trea tmenc.such as reshowingall th emate r i al le a r n e d at acquisition ,wo u l d faci li tatebetterrecal l with preschool chil d r en than a partial reactivationtreatment,suchas re - s h o wi ng a sma ll er amount of the I earni ng materia l.
Anot he r is su e in thestudy of lcnaetermret ention tc the oftec t. of scu r ceof cont ro l at the l e aimnqstage on fac Llicattnqre call inpr e sc h o o l e r s. SOUJ:C€of control is defi n ed assubjects hav ingscrne in p\,;t into th e le a r nin g material ve r sus them no t haVinginput, Inth e present st u dy, sou r ce of contr ol was operati onalizedby varyingwhether the childor the experimen ter choseahidingplace for each object. I t can alsobe te r me dse lf - ver s u s experimenter-g e nerate d learning, as inth e pr esent st udy. Whensubjects have input Lntc the lea rning material ,it facilita tesrec a l l in test s of s c hc oleaq ech i ld r e n andadults .
Rea ea r che r s (e.g ., Bjorklund, 1987, 1988) ha v e argued thatwhen schco lcaqe child r e n and a dultahav e input int o the learningmateri a l of a long-te r m e et en ticn tes t , I:.heymak e U5e of th e i r prio r l:~o wle J ge
of the mate r ia l. Res e archin thisarea le ads:0the questionof wh e t h e r mere ly obs er vi ng at lhe acquia rtLcn stage, comp ar ed with actual l y pe rfo r mi ng atthe acquisition stagein a lon g-t e r mre t e n ti on tes t,will result in different recall performance. Perfo r ming couldpositivelyaffect the knowledgea subjecthasof the le a r nin g material, thus facilitating recall . There is littleev idenceregarding the importance of sou rc e of
con t r o l and of obs e rvinq versus performingan acttonfor p r eschcoLer a intestc of long-term r etent.icn,:-.::;wever.
The effectsof reac tivationand the effe cts of sourceof cont rolin re l ati ontc prescho o lers ne e d tobe exa min ed. Whenresearchers learn more about presc h oole rs' cog n i t i v e abil i t ies , th e y gain more knowledgeabout the adaptive natureof cogn iti v e ab il it y. As Bjorklundan d Green (1992) argued, a bet te r understandingcog n it iv e abili tyin ol de r chi ld r e n and adults requi r es an understanding of it in presc ho o le r s .
The goal of thi s the si s was to examine whether reactivation during the ratention in t e r v a land/o r in put in t o learning at the acquisit ionstageof a long-term retentiontest would fa ci l i t at e recallof information fr omlon g - t e r m memory to r three-year-o ldchil dren.
rnc e e- ve e e-ctde havethe cog nit i v eabil i ties tc ccmpl ete memory ta s ks, butas yet havenot beenstudied ex te nsive ly . Muchaboutmemori e s of old e r ch i;;l r en and ad u lb is known, and there issomeknow}edg e accut memory in in fa n cy. However , ve r y little is k ncvn abo ut presc hoolers' memory,
Re activation
Reac tiva ti on is definedas the reintroduc t ion of a
pc rt icn of anc ri.ein a l eventa t .1time after \.'r. : .:hthe event may have been forg otten . tn a tYP1(;'.'l1test of reactivaticn ,thesu b j ec t fi rst lea rnsmaterral to il criterion, Then,a': SOIMpoint d-rrinq there t ention interval, the subject isgiven a r ermi.d er of
u.e
le a r aed material. Finally, thesub j e c t is testedfo r "on q -Ler m retention of the event. Testingmay invol vesinqleor multipletests of recall or re c ognition. Thepur poueof reactivationis to reinstate(i. e .,r ec onstrucc : the memor ytrac e . For example.sh owi ng a subJe c t " lis t I){sti mu l us words from a paired-associa tes Iio t tr.at heor she learned prev i.ouslymay reac tiva t e the memory of the stimulus-responsepairs. In infant-memoryand animal>
memory pa r a d ig ms , subj ectsare trainedin ahlC} h l y distinctivesetting. At some poi nt duringthe ret en t ion interval , th e reac tivat i on tre at ment is 91'; ",n ;;". thc same setting that th e initia lacquisi tio nto(J;: -Le c ».
Subjectsaresubs e q u en tIyaske d to r e produce t:,:
acquired re s p ons e 10 that aettr nq. aecearct.er; ~1 "V I'.
found that r e actrvatLnqmemoryis et te cti.ve ill strenqthemnq thememorytrace, th e r e by faciLita tinq recal l, for both human and anima l s.ub jec ts f(:ar.1pbe ll I, Jayn e,,:,1966, 1969 ; acvee-ccttter &Ha yne, 191:7) ,
Campbell and Jaynes (19 66) defin e d re in st at e me n t,
another-term for reactivatio n, as.:1,small amour;';of partial pra ctice or repetitioncf :I,learning e xp.erienc e ov e r a periodduringwhit:hsome aspect of be ha vicura s lea r ne d for lif e . Thi s parti a l pract iceis enoughto maintaina res ponse fo r tho sesu b f e ce s who had the exp e rience at th e acqu i s i ti on sta ge, but not enou g hto produc e any Iear n i n g intho s ewho di d not havethe experi e nce . Campbell and Jaynes (1969) demcnstrated the ertects of r einstateme nt with ratsin a study whe re th e y exp l o r e d the rete ntionof a visual d I ac r Inunaticn task le a r n ed in infanc y. The amount of pa rtialpractice aff ectedthe rete n tio nof th e learnedbe ha v i o ur, Long e r dura ti o n s of rei n stat e me nt result ed ingr eat e r re t e nt i on of the 1earnedbe h a v i o r . Thus, occasional remi nd ers of th eorig inal le a rn i ng experie ncemayrei ns t ate the memoryof that exp e ri e n c e .
Atth ou g h the res earch on rat pop u l a t i on s rrev t des evrde nce for theben e fits of re a c t i v at i on,studies on humans are mo r e relevant to thepr e s e n t r eae arca . Res ults of a numb e r of studi e s oninfa ntswh ichus ed a conjug ate reinfor cem e nt par a d igm witha sus pendedmobile (e .s. Bol l e r, acvee-ccIIrer,Borovsky,0ICon n or, &
Sh yi, 1990; Fage nf, Rcv eevcc l l Le r ,198 3 ;Hayne,19 90 ; Hi l l, Bo r ovsk y , &Ro ve e- Co l l i e r, 1988; xovee s acv ee ,
1969; Rovee-c ollier f,Hayne , 1987; xcvee-c ollier S Sullivan , 198 0) have led totheconclus i ontha ·.it possible for infants to remember for lon gpe rrc dsof time. In the paradigm, the in f a n t lear n sth a t kicki.nq its foot causesanov e r he a d mobileto move. t\tsome pointduring a retention interva l , the in f a n t :Eplaced inthe same setting but ca nnot move th emob i l",: th i sis the reactivation tr e a t me n t. At fi n al test ing , the inf ant is again returned to the distinct se t ti:.g andca n kicktomove themobile again, Kicking rate :.: usedas themeasure of long-termreten'tLcn. Infants vhcwere not given a reactivationtreatmentforgot th a t %i cking ca us e d the mobile to move,asevidenced by low kicking rates. However,at final re c a ll, afte r the re ac ti vati o n treatment, the kicking rate was at or near the sa me rate as at ini ti a l acq u is ition. Thi::: findi n g ....·J S cctained for two - mo nt h- o l d s (Gr e c o, Roveeecc lLi er,uayn e. crre sler, f,Earley, In 6) , th r ee-mc n th- ord s {Rov e e-Collier '"Hayn e, in 7} , andsix-mcnth->..b (Boller etaI., 1990; Hill e r aI., 198B) . Alt:.ougbth is tecall is cued, be ingelicitedonly bythe se- p r es entatLcn of a specifi c environmental context, itis similar inch a r a c t e r to the more complex and symb o lic recall responses shown byold e r ch i l dre n.
RcveeeCo l l Le r , Sutt ivan, Enri:;ht, Lucas. andFa gen (19 8 0) s c ated that r e actLvata cn is an impo rt ant mecha ni smth roug hwhichbehav iou rca nbe in flue n c ed . Re acti va t i on ca n prov ide the oppo rtunityfor the cumulativeeff ec tsof early experie n c e .stodev e lo p over lon gperiodsof time. The authors conclude dthat the resultsof veact.Iva tLcnstud ies provide evidencefo r the the o r eti cal dis tinc t ion bet wee nava il a b i l i t y(i. e., st o r a ge ) and accessibi1 ity (i.e.•re trie v a l ) of inf orm ationinme mory. The le arned materi al maybe stored in long-termmemo r y, but without freq u ent remi n de r s of the material individuais are unable to retrie vethe storedin f ormation. Since reac t i vati on does not affect recall, howeve r, this ma yindi c a te an inabilit y toac ce s s ava ilableinformation.
Althouc:;hresearcher shaveno t stud i e d the ef fe cta of re a ct i va t i on onpreschoo le rs' memory, there :"09 researchonthe roleof reactivation inthe memory performan ce of e choc lr-aq ed c hildren . Hovin get a l . (197 2) asked children (2 groups with mea nages of 6.7 and 10.1ye ars) to le a r npa i r sof objectname s by showing the m20 bla ck andwhi t e line drawings (10 pa irs) of obj ec tsonca rds. Aft erbeingshown th e pairs. the ch ild r enwer e sh owna stimulus ca rd and aske d to name
the pa.ir ed object . All s ubje ctaweretrained ':: the cr it e r io n of one pe r fect rec a ll tri a l of all 1: pa i rs.
Inth e reacti vati on con d i t ion, ch ild r en were e xpcs ed to thewor dpa i r s embe d de d in a story fo ur weeks..tter acquisition . ch il d re n inth econtr ol group were not r ece xpos ed to th e words. At fina l te sting, ~lghtweeks afteracquisition , thein iti al learn i ng procedu r e was du plicated. Children giventhereactLvaticn tr eatme n t performed better at final testing th an didchilJ ren who re ce ived noreactivation treatmen t . As didRovee- Collier et a l . (1980 ) , Hovinget al, specul at ed that reactivationmay be inv o lv ed inthe persist ence and incorporationof early chi ldhoodexperiences int o adu lt behaviou r pa t t e r n s . Theyar gu e dth at cccas Lon aI re mi n ders of stimuli , identical or similar eno ugh to stimu li whic h we rep r es ent andno t i cedat acquisition , are effect ivein maintainin g condition ed r espor.dinq . Wit hreactiva tio n, th e re spon dfnq Ls mainta
ine-.
<.It .] hi g hleve l aft er a ti me perio dduring .. hichthe respnn a r- wouldot h e r wi s e havebeenfor qotten. This '11:"'''5 fo r future behaviour tobuildon past experiences.Hov i ng andch o i (1972)examinedwhether the improvedmemory in the reactivation condit ionvas due to the stimulus-objec t s or th e res pon s e-objects ~;-.the
pairs. Using the same stimulus materials as H~':ing et al..; Hoving and Cnoi e xarmned five 9t'oUPS of '5- and
a-y~ar-o lds, va rying rea c t i vati ontr ee trnents,z:.owing stimulus-on ly cards or response-onl yca rds. They fo und that. thepresent ati o nof the respons e- ca r a was the nec e s sary and sufficient reactivator to the ret entionof pa ired -associateslearni ng in young children,
Hovingand Cho! (1 97 2 ) loo k.edat processe s invo l ved in paire d - a s s o c ia t e s lear ni n g to det e rminewhy the re spon se - on ly , and not th estimul us -on ly, condition increasedret en tion in school-ag echi l dr en . They differentiat ed the learningof th e re s po n s e and th e lea rn i n g of the associat ionbetwe en st imulu s and res po n se as two sepa rat e pcccesee s . Hov ing and Cnoi ar g u ed that ...hen only the sti mul us ia q i.ven as !l
re a ct i v a t or, a childof sixyears would not spontaneously producethe response andhe n c e vc ul d not ree s perience thepair ing s. When the r es ponse _3 given as the reactiva t ion treatmen t, th epairsare re e xperie nce d , whic hfaci l i t ates re ca l l . Not al l re s ear c h e r s agre e. For exampl e , Silv es t r i , Rohr b augh, andRi ccio(19 70)stated that th e sti mulus wa s th e nec essar yand suf fic i ent reactiv ater. Rega r d l e s s of the
specific in f l u e n c e s ofst i mulus and response . th a t gen~rallyth epl"OCe SS of reac ti vation was effective .
There is inconsi s t encybetweenthepa r ad Ljms of reactiva tion st udi e s with infantsversusschool- a g e d childr en. In the infant's sit ua tio n, re a ctn vatr on co ns i s t s of putting thein f an t backinto the experimental setting but theki c ki ngprod uce s~.O consequence. Operant analysis wouldcall thi s extinc t i on . In the schoo l - a ge paradig m, r eact ivetLcu consistsof sh owin g theword pairs emb ed d edin 1 stor y . The procedure provides an additional learn ing opportunity; in fact. i t,n a y be considered over- learning. Although the r eu ear ch done inbo t hpar ad i gms has sho wnthat reactivationfacilitatesrecal l. ne It her of the pa ra d i gmsused to oper atLona l Lz e reectLvrtLcn usesa true reac tivation treatmen t. In studiezcf the eEf ectc of re a c ti v a tio n, it is necessary tohave a treatme n t that does not op e r antLy e xtLn q u Ls h !·'iIL-n in'J butalso does not provide too muc h lear ni n goppor t.unity .
Insumma r y, researc h on the effects of r eect tva tton in di c a t e s that even asi n g l e reactivation experienceat some point during a retention inter val will llr,prO Ve subs e q u e nt recall.This is tr u e for 'iafants (e.g.,
10
Rovee- Colliel.' (, Ha y ne, 1987) and fo r school-:l. gech ild r en (e .g " Hoving 1"Choi, 1972;Hovi ng et a1., 197 :;. Ther e is no evidence to su pport whet h erreacti vat ion:5 an ef f ec ti v e means of facilitating recall of info rmation from lon g -term rr,emorywith preschoo l chi l dren.
Self-ve plusExper i men ter - Gene rat ed Learni n g In th epre sent st ud y, adesi gnwas employed 1:0 ex a min e effec t s of react!vatio n ; howeve r, th edeafqn al s o allows for exa rm.natton of whethe r or not:.1vi n g pri o rkrmsled qe of or inputin t othe lea r n i nq :r.a t eria l affect s lonq-termre te ntio nof thatmaterial. Presch ool ch ild r e n were give n the opportunityto choo s e:.:hic h ob jects arehidd enin giv en locatio ns. They may
associate tha t ca rs ar e hidden behi nd cha i r s and , when aakedwhat to hidebehind achair, th eyhave ~~.e op port unitytochoose th e car, Thi s wou ld enha nc e retentio nof theobjectel oc attoripo>.iringf01· t:.at aubject . Int his r e s eerc h, thypctl.e s I zed tha: the ef f ect s ofprio r kn o wledg e combi nedwi th the e~~ectsof reactiv ationwould fac ilitat eteem r na . This que s tio n is second a r ytothe pri maryin ves t igat i onof theeffect s of rea ctivati o n.
Thetwogroups inthedesi g nare re fe r redto as 11
self -generatedlearning, in which case the subjs ethas input int o dete rrmninq the 1 earning material, and experimen ter -generated lea r ni n g,in whichcas e the subje ct observ esth ee xper Ime.nter pr esent the:earning mat er i al, sel f- gene r atedteemtnc invo lv e s having inp ut into learn ing bychoos ingwhichobjectsare ha d den in give n loca tions. Expe ri men t er -gene r a t ed learn:.ng in volv es ob ser v i ng the exper imen terchoosewhi·;hobject goe s in wh i chlocati on , The objec t -loca t ionpalrings are lat e r recal led.
Two areas of particul ar int ere s t relevant ~othis issue of sourc e of control ar ekn o wledg e base, and sub s equen t beh aviourof observe rs and performe r z. Kn owledg e bas e isatheor e t i ca l co nstructused to iden tif yprior kno wl e d g e. Theef fects of prior knowledge can be exerm nedby ueinq the e xp erirr.ent a l man ipu lationof self- versus expe rLraente rvqe n er ated learn ing; thi s studyattempt::: ',0 a naver ':1'1(>qu e stion:
"Doe s havinq prior knowledqe ofthe l ea r ninq :.a t~ri i.J. I
facilita t e acqu isit ion and recall ofthe mater:.a17"
Ac cor di ng to Bjorklund (19a B), a per s on ' s prior knowl e dg e is theconc e p tu a l in fo r mat ion he or shehas about th e defin iti onof and there la tio n s among common lan guage te r ms. A well- e l a b o r at e d kncwledqe c-ase may
faci lLt ate memo r y perfo rmance on long-termreteatton tests (a) by facil i tatingdeliberateuse cf mel':'.cry st r a t egi es, (b ) through re l a tiv e l y automatic ac- Lv at Icn of relations among items, and/or (c)by increasing the activa tion of individual items (Bjorklund ,1987) . Children who make qr e ateruseof their knowledge base have more features in long - t e r m memory associatedwith the it ems . Theref ore. at th e time of recall the activated feat uresshoul dbemor e access ible for chil d r en invol vedin det ermining the learning::la t e r i a l than for ch ildr e nwho simply obs e rved at the acquiaLt Lcn stage. Hemory re pr es e n t a t io n s for chi l d r en whous e their knowledge base while involved indetermining hi ddenobject l ocatton pairings, for example, should be better able to readily activate theserepresentations tha n thcoe chil d ren wh ohav e noop port u n itytc use their knowledge bas e.
Bjo Lld und (1987) stated that themore kno wled g ea chil d has about .3,r et of ite ms and the mor e en ccunterc with the t tene • such as through reactivation treatments, the I ess mental effort is requiredto activatethe items. If this is so, then the use of knowl e dqebasein acquiring information t o-beeI earn e d,shouldleavemore of on e ' s limited processing capacityfor ot he r cognitive
act Ivt t.aes .
Th evcr kof Bjorklund(19 8 7. 1988)an d H<J:"'- (1985) indicatedthatpriorkncvledqe is an import ant explan a to ry componen tofmemor y perfo rmance, 7he prior knowl ed g e strength ens the memorytra ceand fac ::ita te f;
rec al l. Fo r example . ina pair e d- a s s oc ia t e stas k the subject"sknowledge ba s e mayinclude tha t two vc rds are frequentl yencounte r ed together. Whengiv en astImulus wordan d askedtochoose another word topair :~with.
thei r choice s are ba s ed on theirpri orknowled ge.
'nu
o make s 1earning easier and streng th e n :!;them':mc=-j't.re e e becau s e the subjec tsstart out WI th a non-ze r otruce.Manyothe r researche rs ha ve added to thi s deb a te (e.g ., Baker-Ward, Hess. &Flannagan, 1990; Fe l dmanEo
Acred o 10,1979;Rudy&Goodma n, 1991). Enh ancedr eea II ,Jflea r ned.na te d],1mayoccur forchi ld re n as :..."Ul)tj1::
four yearsof age (e. g., Fe l dma n&Acz:edo lo .l::H) . The s e rcsults illus tr a t etheimporta nc ecf mar.: i1ul ali nq self-gene r3t~ dve r cusr.-:-:pe ri me ntt:r-<) e n":ll'3.to<:>':i :-: ndittcns of recal l whenst udying early memor y de ...~l o pm,= ~.,:. When subjects have input int othe learni ng materiaL. ~.h e y have theopp ort un ity touse prio rknow ledge. '''he t her or not le arning and re call arefac ilitatedis impc rta nt for practic al an dempdr Le aI re aso ns. Practicall y . i t1:;
importa nt tokno wthe bene f itsof involvemen t :::
lear ni ng forsuch purpcses asdas i gni ng ed uc aticn programs . Emp i rica l ly , it is imp o rt a n t for res earchers to knowwhen designingstud i es of rnemory tha t :'!ie mo d e of invo lvement (Le ., actively inv olv e d , as in self- generated le a r n i ng,VS, passive ly inv olved , as in experimente r - gen er ated1earn ing) wi11affect the perfo rmanceof young child ren.
Inorder to examinetheimp o r t ance of.1kr.cvledqe base,Bjor k l und andgernholt>(1986) andBjork ~ ;md (1988) us ed the paradi gm of recall ingself- ve n u s experimente r -gene r atedwo rdlis t s. Bj orkl und and Sernha ltz mani pu l ated th e ty p ica 1ityof words '..Iith q roupsof good and poor I3-ye a r-ol dre a ders, For the self-ge n er a tedli st, the typi cality of the itemswas .Iete rnd n edl-asedon['ati ::.g dat a obta ined~:: cm~he
childrenina previous se s s i on. Fo r the expe rirr.e nt ere
qenerated ILst , typic alitywas based onno rms :btai ned fr om.,sampl eof colleg e s tuden tc . Duringth ele arninq stage of the study, sub jects received twolLsts consisting of setsof typicaland atypica l it ems for recal l. At re c a ll,perfo rma nce wa s betterfo r the typi c a l th an for the atypicalitems fo r each gr oup of ch d ldre- ....ith bo th the self-generat ed andexp erimenter>
15
generated li st s. Good re ad ersrecall ed more fcr -he exp e rimen ter - g e n e ra tedl Lst c t ha n did poor re aders.
Wh e n the 1 ists we r e devised1:'j'the subjects,r.caever , therewere no re call differences bet wee n the goodand po; r rea d e r s. Bjor kl und and Bern h o lt : argued that th e dif f e r e nc e s inknowled geba s ebe t weenthe goe:! and poor re ade rs we re re s ponsib lefor the d Lffe r ence sl:l recall foun dwit h the expe r im ente r-genera t ed lists rather than dif fe r enc e s in str ateg y use. Theystat ed that performa nceva s influ encedby nonstrategic, organizational processesas so ci a te d with the c e l etivelv effcrtl ee e activation of we ll -e st a b li she d s erne ntLc memo r y re l a tio n s .
Bj o rkl und (l9aS>' inexa mi ni n g how knowledge base 1s affe ct e d by age,st udie dchildren's strat eqies for rernemberLrrqwo r d li s ts(:3u b jec t :: we r e from -rre se 4 md gr ade7). Th e typi ca l it y of the vo rds wa sjud qed either bythesubjects or byaduk t rat e r s. 5jorJduncireferred to r eae a rchon children's free re c a l l (E jct k l'.::-.-l&
Be r n hol t ::, 1986; Rab i n owi t z , 1984) and cuedr e calI (Acker man , 1986; Bjorklund &Thomps on, 1983;~'hitney(..
xunen .19 8 3 ) inwhic hperf o rman cewashighe r fcrsets of typica l than atyp i cal ca t e gor ye x empl ars. In the pro c edu r e , subject s learneda vc rd list, and d~fina l
10
teatLnq th~:t ve r e given fou r re call tests. 01:!.e:
chL ldrenre c all e d more word s than younger cht l
c
r en , and recallwas ']reater for typical than for atypical categoryitems forboth self-g e n er a t e d andadu : ':- generatedli sts. Recall of the aty p i c a l items :or bot h old e r and younger childrenwas greaterfor subjects receiving self -generatedlists than fo rthose receivi ng adult-generatedlists . With r-cr e knowle dge , prece s sin g becomesmore effi cient, thereby enab1ing easie r to ent riesLnsemanticmerno ry.In summary, Bj or k lundand hiscolleagues (Bjorklund , 1981 , 1986; Bjorklund&Bernholt: , :986 ; Bjorklund& Bj or klund, 1985) fo undth a t knowledgebase is an rmpo rtant, explana tory compon e nt of memory perfor mance . In the ir studies, reca llwas better in :.elf-g en e r.:l te dcc n dttLcn a th an inexp e rIme nterejene r ated condittons. Thi£: learnin g co n d it i on vari ab le int e r act ed , howe v e r, withag e (old e r VS• .younq er) , readi ng abilit y(goodvs .po cr) and typic al Lty.
These c o ndarea to considerin examining:the
etree e e of source ofcontrol is the di ff e r e n ce in subseq uent behaviour of obs e r v ers
(e xp er i men t e r-ge ne ra t ed le a r n ing ) an d per formers (sel f-g ener at e dle a r n i n g). The que stion in th i s area of
17
obs e rve r sve r s usperfc rme r s is vhether obs e rvaz j actio n tc be late r recalledwill affe c tre c al:
dif fer ently thanperf orrnirrrtheaction . For ~:.~
purposes of th e pres ent resea rc h, thisquestior,\5ac ked rega r din gthr e e-y e ar-al d s. Fellol/i n g the l oqic of his theo r y , Bj orklund might arg ue that pe rfo rm ing1 task wou ld strengt h en thefea t ur e s in memo r y oe s cciat adwi t h thetas k. Attime of fin al re c a ll, th eteatur es wou lJ bemore ac ce ss i ble fo r perfo r me r :::of the task·.hen-by making recal l lesset tor t.fut. i\chafd who .int,.. rac tc with ob ject s to-be- hidde nat the i r hidin g tcca rion may have repr es e n t at i ons of movement and even t s th3': are linked to location s {e.g .,CohenloCo h en, 19a 2;. Itte also poaaib I.e thatthe mot or activity invol vedin perf o r mi ng theta skma y inter f e r e wi th es t abli :;h ir.q the memory rep res ent atLcns, .a ltho ue h t ht o poaatbi litytc not ernpLrical l y support ed. aaker-Ward et al, (199'0' found that performedactions wer e retaine d bet t e r tha;",
familiar an d meaningf u l. They also arqueci, alterna t i vel y , th atpassiveobse rv a t i onof ancthe rts acti v itr es ma y direct thesub j e c t' s choi c eat reca l l , a possib le sup p ort toth e specula ti on that pe rfc r rni nqma y cause interferen ce.
is
Cornell andHeth (1 9 86) exami ne d obs e rv ers and pe rformerc ir.a task of hi dingand Iate r fi n d ':'r;; 20 mar bl e sin aroo m. Thesubjects, in kinde rqa rtenand grade two . eitherhi d th emarb h-s themsel ves, ene ee th e loc a ticn s bu t chner ved the experLrae nte r hi d e the marblee,or observed the e xpe rirnente rch o os e t he locati on s and hide th e marbles, The subjects immediat elywe re re quir e d to find th e marbles. cen e r al ly , alt h o u g h childrenwhocho s e thel cc ations
used c cme Lamof strat egyin their choices , ther evas nodiffe r en c e in re c al l between the groups. Cl'".ildren used memories ofhidi n g plac es to direct th e i r search.
The in f o r matio nobtai ne d frem observationwas suffici ent to es ta blish th e se memori es .
In centras c.performingan ac tivitymay fac ili tate
cch en, 1982}. ThH .. is alsoevidenceth at cbs: ;v i ng is suftLcientto form reprea e ntationa inmemory a:-..:!.t hat;
petformers (corne tI &Bet h, 198 6 ). This la c k :: .:;i g nifi c 3'.lt dff ferencemay be a result of the ':.j'peof ob je c t s beinghidde n; the objects (ma r b l ecj were alike, Di s tinc ti v e cbject s may havebe en more interest ing, the rebyincre asinqmo ti va t i onof su bj e ct s to findthe
19
cbje cts. Toanswer this question, further ev a c ence using obj e ct : th a t would int r i gue presch o o ler s :~ needed.
In th e present stu d y , the recall of cbe e rve rs ve r s us performers was examined. The ob ject a used were nove l and age-appropriate t.vys. lnvolveme nt wi th hicll ng the objects(i . e., choosingwhich obje c ts arehid d~nin given lcc aticna ) is expe cted to facilitate acquisiticn and recall of the hidi ng lo c a tion s . rh tcexp e ctation is based on th ere s e a r c h which argues that pri or 'i acvtedac facilitates lea r n i n gan dre c a l l (e.g" Bj ork h.::"j&
Bernhc lta, 1986)andthe research whi ch suppo rta th a t performing as opposed toobserving anactivity fa c i lit a t e s le a r ni n g and recall (e.g.,cohen<.cch en, 1982).
subsequent behavio u r of cb e eeve ea and pe rfor.ne r s facilit atelearningan dre cal Iof mateitat is unres cl ved. The ine o n siutency ir.r e s ear chr eec r de whether or not zelf-gener at " d le a r ninganu/o r ~~rf ol ming a task in a test of long-t e r m retenti on taciLitatcs recall. Having priorknowledgeof the l e arninq material may S;ive aubje cts the opportunity to use thi::knowledge to strengthenmemorytraces. This use of p rior
knowledge faci litatesacquisi ti onand reca ll c:
inf o r matio n, 3lth ou g h thereis no evid e nce t ha-;thi s is so for th r e e-iye arr-olds . The kn owl edgebase E':.e r a lur e inc ludesa number ofstudi e s ofsel f- ver sus expe r imen ter -g ene r a t ed word li sts, and stu d i e s ofthe effects of beingpermittedto us e priorknowledgein pai red- asso ciates tasks. The re s u lts of th estud i es show that having input into determining th e list s fad1itates reea tt,at 1eas t for school-age -=hiLdrenan d adults. Her efe ature s are encod ed , whic h makes the lists more readi l y acces s ible at timeof recal l.
Regarding thecon t ro ve r s y about the eff e cts of observi ngversusperforminga task, researchers argue that performe rs recallbetter th anob serve rsof event s (Ba k er - War d eta l . 19 90; Cohen&Cohen,1982)and, a lte rnatcly, that th e re is:1 0 dLffe r ence ce tve en obs erv e rs and performe r s (Cornell& Het h , 1~8 IP . As well, ther e is ev ide nce inth e tvc -rc hcfce altercaticn task l Lte r at.ureth at a tas kof hidi n gandse~k: ::'l 1 ob j e ct s, a widelyus ed tas k in this area, maycebe y on d th e cognitive ab i l i ti e s of three·year-olds (Rabi n owi t z &
DeHyer, 197 1 ) . Theserese a r c h ers would argue -n e e examining theef f e c t s of observing versus perfo rmingby employi ng a p at-adLqrnof hiding and seeking ob jec t s would
21
be inappr op r i a t e , <:11though ethel: rese a r che rc (~ . ;;., De t.o ache,1986)wouldai c aar ee.
~HiddenObiect Locatio!1§.
Inlong -te rmretentionstudiesof the effects of reactivation andsourceof control,app r cp r La te me t h od s of testingare necessary. Retention of vo rd lists, su ch as usedin Bjorklund (1 9 8 7, 1988) , Bjorklund ad aernhoIts (1986) ,Hov i n g and Choi (1 9 7 2), and Hoving»t 011. (1 9 7 2) areapp r op ri a t e in te st ing schoo l -a ge children,but moreinnovativemethods are ne e de dwhe n testing youngerchi ldr en. La n g e , MacKi nn on an dNida (1989) stated that the less cognit i velydemand ing the task, and the more attractive the task , the morelLke ly thatpreschoolerswill tend to automatically respond
me mo r y- f-::r - h i dd en-obj e ct.s parad Lqrnto atudy t.vcvyea rec l d ch il d r en' s l onq - Ee rm rete nti on .:ohetubj~ ,: t :; ur.der ctood what ·.."a s required of th e m and ...erec ap abl e Jf :,m p l,~ ting the task. Th ecu rre n t researchus e d a si mil ar ~.J.radigm. Th e r e areconflictingopinio ns inthe ltter atur o as to wh e t h e r pres ch oo le rsare cognitivelycapal:..l ..of under~tandingthe conce ptof "hiding". Fl av.e1 :, Shipstead, and Croft (1 97 8) ..xamined chetbe r a rnot
j'ou n q children t.etvee nthe ages of 2'- and 48-r-cnth s ve r e able tohide obje cts fr oman o ther person . 7~eya1.:::;0 exan.tned whet her the aubje cta we r eab le to dete rminei f theot h e r pers on could c ee th e hi dden ob j e c t( s; . Even the younqezt;subjects knew ho w to hidean object from the experimenterby putting an object on the s: ieof a pa n e l oppozite theexperime nt e r. onlythe ol der child renwereable to hide an objectby pl acinca pane l be t wee n the ob jp.c t and the experimenter . All chkldren did we ll ondeterm:' n i nqvhetbe r ase co ndexpericent e r couldsee an obj e c t when th e first experimente r held a panel in a cert ain po s i t i onan d asked the ch ild i fth e second experimen ter cou ldsee the objec t. Thus, the r es u lto of Flav e l l et 03.1.supp o r t the viewtha t 2.5- to 3.5-y e ar-oldchildren un d ers t a nd theconce pt o~ hiding.
Lemp er c , Fla vel l, and rtavet t :1? 77:, 1:l-::n min i:lg hi ding beh avi our,ha d youn g childr e n aged1- tc a-vee r s hid e anubject from the exp e rLme nte r , Eit h " r :~.e::h il d aas to move r be obje et.to hid e it beh inda par.~:. ~~th e chi ld waoStomov e th e pane! to hidethe object. Three- yea r- o l ds pe r formed at ceiling leve lson almost all tasksus e d inth e study. Lempers et al . ccnc ludedtha t byth e ageof three ye a r s children demonstratethe kno wled g e th at object sca nbloc k thevisi on of cthe r
obje c t s . They found that threevye a rcoIdu kne e :h atthe eap e rimente r ' s perception of an abjectis .independent; I,)f their own. These young subjectsde no t e-xhibd; much ego centr ichid ing.
In contr aet. Rab i n owit z. andDeMj'er (1971; tcund tha t thre e-ye ar-aldsdo not have the cognitive Jbility tocraentc e: the ydo not have thesystema ticc cqru ttve abilities forhidingcr searching. Inthervo-cbcace al ternationtas k s usedby Rabinowit:. and OeHyer, the chi ldren ch oos e between tvc lo c a t i ons to findt.idden objects; theym<1Yalsohide theob j e c t. Thair abiLity to hi d e in an un p redictablewanner vaso xauuu ..dandit wa s determined no t to be present at age tb r e eyea r s . The autho rsalsofcund that th e abilit1 tose a r c h comes onl y about;sixmonths before the ability to hide. According toP.abino\o:it:. Jne I:~M~'er . ':h", t'<~ !,'t' <:, ~h'~
eubfeet s inth e present res e a r ch we re ')n 11 IJeg::,n i ng to havethe ability ':0sea rch.
dif f erent from hiding objects as in the Le rnp er c"!t c l . (l977 )et udy. The alternation taskLite r atur .... '/il':'wS hidingas a purposeful strategyrath erthanas an innate abil it y asdescribedin the t.emsers et al.study, Therefore, re s ea rc he rs suchas Rabinowitzand :eHi'er
:-1
(1971)'../ho claimtt.at thr e ecye arco l d z ca nnot hide may be refe rring to strategic hiding,
In the pr esentctudy, pr elimina r yinvesti;ations ind i cated th a t threeeyeareo l da didund ers ta n d vhat was be i n gexpect e dof them whe nas k e d to hi d e an cb jeet . Based on th e resultsof th iz testandon th e resea rchof bothFlave ll etal. (197 8) and Le mper s et at. (1977 ), I cont en d that pr esc hool ch i ld ren und erst a nd th e :o n c e p t of hi d ing ,
Thememory -fo l:'-hidden -objects?aradigmrequf rea an abilLt y tosearc h as wel lasto hide. Sea r c h i::; for hidden objec ts i!l wellwith in theca p a cit yofiaf ant.s andis useful inassessing thememory skillsof toddlers
an d you n sch i ld r e n (Bjork lu n d E.Mui:: , 1988), :'-eknoa
fro mthe res e a rc h of Het handCo r n el l (1980) th a t
ef fectivel yaf te r ob s ervingmodel s, thei rmothe r s , pe rfor ma se arch tas k, Ch ildr e n35 you ng as t::'::e eyear s cf ag e ca nsear c h ef fec tiv ely in a natura l envi rcnraent wi tho ut observ ing a mod e l . Sear chi n gse ems tc be a skil l thatde v e l o ps earlyin life.
Thus ,in accord withthe re s e a rchof De Lc ach e (1986), DeLoache and Brown(1.98 3), DeLoache ,cassidy, and Brown (198~), Flavell eta l . (1978), and t.emsers et
a l.{l'2'7i}. r:- esc~. c ci chdl d r eanave':hcJ.bi E '::' ':ct'.:'d e
be appr oilri3.t e tote s t r eeat
r
cf in f:rrn 3 ticn ~:'':::\1"0 9-termmemor~'ir.three-r e ar-o ldc~ ildren.
Present Resear ch
hl Pothe ~::':. :'st~.",~::':'1atea t ;::f !o r.;-t e rr. .retl':'".':.':'O::l... ith three-year-o l d eubfee ts, reactIvatton of aror ':.:'onof the original learl'".i:l7 materLal darin g th e r etez.ticn Lnte rval ~ill facilItate recall of thatmate riaI. I pcctu late that the strcnae r the rea etLvatLcn, ~:,ebette r willbetherec a ll. testec by gi-01ngcomezub;.;.~tsLess infor mationduring reacttva ticn. 'n. :!.shy p othe zisis b...acdonanal ys e a!:.1 resear che r s stt:.d1in ; U.t! :":npactof reactivation(~.9.,Hay n e. 1990;Hoving t.Cha :-. 1972;
Hovir.~et al.•197:::; Rovee-Col lie r t. Hayne. I n,:,)who
arguedthat the amountof reactivat i ondoes fad li t a te recaI 1.
I aLc c hypo th es i:edthat thre e-year- old::.':'ldren
long·':.~=;.1 ::etention test ....i11 havebe t tcr ::~ cJ. :~ ::f that
T~.i .;;hypo thes i s is based :m the ',;orl:~~res ea rche r s {a . g•• Sakcr-Wardet 31. 1990 ; Bjo:l:lun d,
::. n :-.
19 8 9 ; Cohe nSCohen. 1982; Pel dman&xecedete, 197 9 ; P,udy t.Goodman, 1991} wh oar gue d thatmo r elm owl cd g ~:>bout ..hat is learn ed.andperfo rming r athe r thancb s e :;"li:-.~0.task
Impr cves re eatt ;:If :.Ih a t is learne d. : wante d :: determ ineif t.3 / inqinput :';;.t olo!,tr::ling a.t:l.:::!' :.,;
effe etIveir.f,"h.i lita ti nq recall withpreschc c l e r a • If rea cti vat ionfaci lita te s re calI inin~'J :lts and sohceLeaqe chil d ren,theni tmay aLac tactl Ltate rec a ll in pres ch o o l e r s. Furthermore , if ~~l ~-gen e rat"l learni ng facilitate s ac qu.isitLcn an d recal l wit~.thr e e- ye ar-olds , th ensubj ec ts in the:;el f-ge n e ra t",d ecn ditLon qiven a eea ctrva t.Lcn tre a tm ent should havethe beet re call per formance. 1'hisposs ibil i ty.)f the s e ~ffect:l isthe reas onwhy th e two variable s are exaeune d inJ.
taskwhichre quire dthree-ye a r- oldch il d r e ntc reme mber the locationofhi dde nobj ects .
:s
Method
Su b-iectc, The subject~were ')0thre e-year-c !':! :!"li l d ren (M=39mcnths, SO:: 1.96 ) . Th e subjects wer eae l ected from :!4 dayc a re centr es in St. John'.=. Pe r mi s s ionfcr eachch il d's parti cip a ti on was obtaine d bya lette r of parental con s e nt ,
De s ign . ~hedesign '..as ·12 (se l f- ve r s u s expe riaente r>
generat ed lear n ing) X:;(r eac tiv a tio n, partia l reactivation, co nt r ol) :~.;(t r i al) de s i g n, ahe r e the firsttwo factorswere between-s ub jectsand th e last factorwas within- sub jec ts. The de pe ndent var': ab l e was tota.l number of error son eachof foul."tcna-tera retentton test trtal s .
11.ater i::11!j;10 4pro<"e du r e , All ch il d renweretestedat.
theirdaycare. Duri r:g the acquisitionph a se, ::.~l cu bje ctn l e a r aed thehi d i n'Jl ocatLons of :S objects (b a ll, book, ca r, car d s, cow,crayons,e r as e r . fl ov er , barmcnt cc,man. plane, cet ssc cs• spoon, c unqla sa e s, wat c h, '/0yo). Asub ject was fir st tak en intc a cenar ete roomthatwas appr o :dma t ely 3meters~:3 meters . The crate ri a fcr choosing the room:.;a s that it
2'1
befamilia r to U.<;-ch i.Ld, ~h a lit b~free!~-o;:-.
tecattees(e...be hinda ch air.under 0\,:-~ ::h :':;".l. ;'he child~asthenintr odu c e dtotae exp erimenter!::ia Jaycarestaffmember, and afte r cs t a Lli::h ingr apport, theexpe rimentera::ked the chilJ:"Wou ld IOU~:"::eto
~la y3.aame withme? I veutdlik e to sho w youz ome toy::
that I have in thi s bag:,an dthenwecanpi30ya '3m«:l wi t hthem, " chi l d re n tested with ineac hda ycarewere dt str Ibutedaa eve n l y,1.::; pos s :'bl ~acr ocs the c;x bet...een-s u bfect cel ls .
The experimen te rand t~. e·:hlld::a tin the-ai dd'l e of the room onth efloor. and the experime n t er tack the items at ra ndom from abag:andpla cedthemcn~~.e Lloo r infr ont of th e child. Afte r bei ng: showneaet, :'t emt.t.e (;h :'~dlola:::as.ked, "',Jh at i.:;thi ;; ~ .:111~·j';"" !f t~"· "h':'!l did~.:;l t rez pen dcr did~.o tI:r.c :.l. ';~... ir. fcr:n:l.t~:".
provided .::1.:.1',.; =-:~~:-.dme 301ub jcc t cccur rcd .."
thechild'!: obje ct name wa s acc ept e d andus ed~~.rou ghout the atudy.
Then thechild was to l d thathe/s he and tt.e experiment e r wer e gOl:1';!to pl a yagameof
30
"ht d e-nnd- e e ek" ;,;itl". H.e object s . The £: l1 ow::. ; ins t ruc t i ons wereuced : "11€'are goi:-,g':0;;1;;':11jame':If
~.i 1 (:-J. n 1- z eE. k. !:o.: ':inst ea d of youand I h:.din;.'.Je are 90i ng to hid " these toys c r cund this r ccm. Whenae are finishe dhiding them, you are going tohave to fi nd them."
In ".111inst ance s thechil d·...assho wnth e lccetion fo rhid ing th e objec t . Withir,ea c hd aycar e the lo cat i ons ferall ch i l dre n ue r ehe ldconst a n t. The on ly
fa c t o r t h a tv a rie d·. . .a swh i c hc bje ct va sr.i dd er.1t ea c t.
location. Sub j e d s ':'o theself -ge n~rat e d :or.d:'~io nwer e ask e d wh ichobj ect th e yvculdli k e to !-. idei ....each cf thegi venloca t i ons. The followinginst r uctic:.s were used: "Here i:; ago o d hi di ngplace. Whic hof tbe s e th ings wo uld youlik eme to hide here?" ~n the
~h·~ ~vl 1owi ;-.9'irict ructLcna : "uere i'::'l9cod h::: 09 31
place . : aIT,:j ci ,. gtol,ide the_ llere,"
In bot h c ondi tLon e, theexpe r Lmente r actual l ypIac ed the object in it shiHn9 loca. ti on . 'I'hi.= wa s the ~:'~ ststudy trial.
:'I.ftC l the...tems were hi dde n. the....xp e r Lmenter asked
the ch :' :c!.the Loc a ticn of thecbfectr in apt"-=-HL":l.nq c d randomcrde r. Tl-, i ~was the fLr at -ect '::ia l l02ll recall wa s randcrruced . ai th thec cn straint ~hJ. ~ cbjcctc which were hidden las t verenot;'\mong the fh .::'.to be asl:ed fo r inor de r toavoi d se rLaI positi on effec t s , Th e childwas askedto poin t to the <Jb j,~ct frc-;vher ....
he/sh e vas seatedwit h" u t ie ve al Lnq the cbje ct Jt the locati on he/shepointed. The exp eriraen tcr ;:;a: ::; "~ am go i n g tcask you tc t el I mewh e r e thetoy s arer.Lddcn one at ati me . Youace not a l Icv cd ~~ :,;~I: .: ~:~ C cb fe cts. You are only all owed tcpoint tc vh e re j'CU think th eto yis hddden;" Ifno reu pona e to ~~.<:teqtrcc t to pointtoth e objectwas given , the chrlJca c asked to stand next to vhe r e the ob je c t was hidd en. [~'.h i :::W.) $
unsueeesstvt • he/ s he was askedto te l 1th e cxperimen t e r
ct.oI c e wa:,;take n :,:;:._.;/;,.~[ -lt,.;.·;·~~'
Aft e r asking for th e l ccctLonsof the1(; ccfectc , the exp e r Lrnen t e r again chcved thechi l d the,~!:. :·~ ,;t:;and their Iccattcn s ina pre-arranged randomcr d er .thua avoidin g cerial scsitcc» andshcr trtc r m-memccy·;f fer;t. ::;).
cr.ce;)qair. ;.test tria l ;.oasedmf nizte r ed aher e ·. ~. ed.i l d
"a sasked . :n~ r,r e-<tr raul;e dr an d c m order.th e :'cat i o n
folLcve dunt.:.l tt'.e ch i ld reached a crite ri on c= ~w o ccnsecuttve p~rfect recall trials. 1-.t thatti;;.e the ch il dwa s ret uroed tohis /her norma lacti vit1 ·....ith the ot her children at the daycare.
Threeve eksafter acquisition. cn eethLr d .:: the child ren returned to thetes t i ng room .... ith the experimente r and were she-enthe ob jects (r eaet iva tteo tre atment cond i t i on ) . Oponreturnir'\lto the rc cmthe e aper imente-r safdt "0" you remember being here '.tithme, and playing'a game of hide-and-seek? We used ,;~. es e
to ys . I'mg01".9 tc showthem to youagain." ::..11 subjectsstated th e y remembered th e acti v i t y . ;.ft e r
"Th a t'.,:. ",l~ vetre 90in9 t c 10 today. :'et ',: ; c b ack and ::ee\.Ir•.J.~ ':.t.e "_tr.o!r boysan d'lid: are do inqn.::;.,",..
1\.n o t h eL" ':.h i l"dof the chd Ld r en re tu r aed tothe :estinq rocc vi':.~ the expe rfmen t.er thre ewe e ks aH e r l.:::;.u i sition but wer~no tahcvn th eobjec t s (pa r t :'al reactLvaticn treatment -.;on dit i on) , These subjec ts wereaske d by the experImente r: "00yourememberbei nq herewit~omeand p1 3yir,ga g3me ofhide -and -s e e k? I just wa nted ':.0see if
"
j'OU remembet-ed, Le t' z gobacl;andsee\~h atth,::cther boys andl]i r ! 3 are doing now," ':'he ::~ m<li n i n .j :~.ir d d the chd Ldr er;we r einth e icn tr o I ccnditicn a" c.'~"' H'not seen again in the experLme nt.a lcon te xt until ~;':".al testing.
Fo ur weeks afte, acquisitjoneac hchildrc rur nedto the testing roomwi t h the e xpe rime nte r. Eac hvas told that he/ s h ewas goingtoaga i n play tb ega m...,,~
"hd devand-cseekv" The follo wi ngtnstruct Lcnc vcr egi v en:
I alreadyhave the toyshid denvber eth e y ve re :-.idd en before. I want tocee if you remember aher e t~....y are . Where didwe hide the_ ? Point towherewehidit,"
There ver...four test tria ls ~it hno further .::;t;.;,d y oppo rt uni ties, Howea.n d Bra inerd (198 9 ) reccmmended
to ~y. a i7l~ n,~ chan g e::in perf ormanc ebetwe e n two;:: morc testc
0:
r et.ensa cn. aet en ttcn performan..·: '·:-t.:: ':!.-'Thechildrenwe re asked in a pre-arranged rand om or d er che re the itemswere hidden. As at acquiaiticn, theywere fi r s t as ke d to point to th e obje cts, If th e y did net respond, the y were asked tos t.and I'IE:l': t ~othe
:.bj'J-=~. !~ ~!".,; i':Igai=-.Lid r.ct re::pcnd. t.'1.ey.~-:: ~a:ked t::.'~1: '.t-.e ·~ r e r ':':ne l.Lr :...!"•.;ret!".t! :b j eo;t ',Ja: :::. ..!J en . f.nl r~::po n: '!'",hit;hind ic a ted 1 defi:1itecb e tee va s acce ptcd , At this time theobjects aeee r:.ot a.::u a ll l hidden,sinc e t.bere would beno stud ytrial s ar;::'the test tria lsdd d nct r equ Lr e r etrieval of the ;:!".~·si cal cbfect . Thi s als o ensur e d tha t thechil d wou l.::!. no t reveaI the ob jec t du r Lne a :sttr LaI , Tense c : ..da ve r e allowe dfo r a resp onse an d the fir s t ona ve r va s c co red.
Resul ts
Anahsisd i.;;cu'zition Dab
1".0ana Lys I a uf va r i a nce was ccnd uctedon~~.e
acquisitio:,\data for the 90 s ubje cta in th es~:·: ~r o u ps. The de s LqnwasJ, 2{s eLfeqene ratedva rcun e xperime ntcrr-
genera ted ) X 3 (reacti v ati on , pa rtLalere ac t.Lvati en, control) be tveen-eub ject sde s i g n. ~hedepcndent variable was to t a l numb e r of errors. The anal yaLsof
interactions (se e Table 1) , Subjec t:::ineachet thesi x groupsle a rne d to criterionwithin3ppro xi m.:lt,<:, five study-testtrials; there was nosi9'nificantdif fe r-enc e between groups in howmany stu dytl:ia.l ::it ';.':;01; Lore ad, the criterion of two consecuti veperfect r eca ll a of 16
"bject -l oca. ti onpai:: ':':-.g::.
Inser t T-J.b:",:: abouther e
Althoughthe initial "NOVAon the ac qufcitionda t a showed nc mai n effects or interacti ons . An ANr;':'lA was conducted on th e re t e nt i on data. Thi:: was donetc ensure that the resulta obs e r v ed wil l be at t;: ~!:.·.It e d
36
'iithi r,l::'mit~cf e r ror t= th e tr e a tm e n t ve riebl e. The
'I:::C,)f
;'\.ur.o·/;, r .e
l pa toe l Imt a ates purLous c:It.: ~;,: :feffects , zuc t.).z rate of tearnr na at the acquiz ct.Lc n :::~,o.geof a two- :;t a q e e xperi.rnerit, (Un d e r woo d , 19-!~ ). The def;i g n was:(s e lf - g e n er a t e d versus exser imen te e- generated )x 3{z-a a ctLvation , part ia l -reacti vation , cont roll X 4(tri a l), where the first two Ea ctc z-s were betwe enez ubje cta and the last factor was wi thi;".-zubject.
The dep end en t va riabl e was tot a l er ::o r s on eac -,of the
~O) UL long -t ermretentiontest trial s, and ',:"'13.cv a rtate cas tct aI errors at a equi..tion.
The cova ri a t e W3Z significant [F( 1 , 8 3) : H. ~l , E.<
0.01), and the in t er a c t i on between source of ccat r o I (:::131f-ve r s ua experimenter-1en era ted learning) end trial approached::::ignificance, [F(3,252) : 2,62 , J2.; 0.0 5 17 ) ::::13 13 Tabl e 2). 1I.pp roximat el y ~Operc en t -:f t~.,;
ac quisitI cn meteria l vas r aca l l ed byeubjects ::,all s I x grou p:::. The ~.l ct th a t thr e e -:J e a r~';: .l ::verc J.=:~ to r emernbcr :..:itbSOpe r ce ntac c uracy th e IOC'3t::'or. :~ le
further research.
Insert Tabl e 2. about here
sf nee theccver Late\:az .:i gn i fi ca nt ~i .t:'. ~!",o= ,...
vbc made f~ :l el: ~,:>al·n.in~or r orc ma de ~e H ~r ~"C:l :: er rors), the estimated r;::~u lJ.ticnjararncte r (;;'': ~'J. s tcd
mean )for each LeveI .:if H.e ind e p e nd en t va rLablewas ca lcu la t e d. The adjuste d me a ner ror rato fc r e-ach test tria l arelist ed :'11Ta ble 3. In the aelfeqeneiar ed con d i t io n, th e r ewe refe wddffer enccsbe t wee n ~:-.e tota l nu mber of erro rs in eachof the thr ee t.ree tmer. ; condi tion s (r e ac tivation, p artialcr eactLv atLcr;, an d
subjectc rece Lvi. nq thecontr c It reatnent '~~n1eJ. t.onav e slightly more er r ors thant3 0SC r e ceLvLnq the '',10 reactivati on tr e at me n t s . 'rber e was ve r ylittle diff e r en cebetveen pe rformance forz ubjectz reeetvina the react i va ti on orp a rtLalvreac tiva tLcn tr ea tn.ent.
Inse rt ~a b l-: -: abou t here
adjustedmean erro rs calculat ed on the self- ar.::
experiment er-g en er at e d con d it io n::: we r e an aly zed usi ng a Newrnan- Keu ls test . Therele van t trial me an nUIT,bf:l." of e r rc rn are list e d in 'rable 4.
::9
Ins e rtTabl-=4about r.ere
Th,~ nevean-xeu ts test (2 ( .01) indicatedthatthe
mt.e r actioa wasdueto performance beingpccrer on aubcequ ent; lonqvter m retention te stc within thezel f- generatedconditi onrelati ve to theexserime ete e- qener ated condi t ion.
In summar ..., anANOVA·...as conducted onthe ac quiciticr;'~J.t ,J. . :lhid. Lr.dLc ated
:.=
::'.ai :-,ef~c: :ZInte r a ctl onn . !\n ANCOVAwas then ccn d ucte d,'..,r:'':h He dependent variablebeing tolal err orsoneach :: th e four long termr etent Iontest triats and the ccvariat.e bei n g total err or sat acq uis i ti on, The cnly s:.;;aifi cant ef fe ct was for thecovari a t e . The interaction»etveen cc urce ;If ccr.t rc l andtriaI appre ached.::ign ::' ~:'.=a n c'= ,
cf th e tcna-tar.n r eteuticndata refLecte dth at ':he iat or a.rtton approach ed.:ignif :r oncc beca us e ':~.~:~vea a
tri a l s for th e experiment er - generate d cc ndtttca anda slight inc r e a s e fOI: the self-generated cond i t i: n.
Dis cussion
Inthe present expe riment , thre e-Yeareo ld c!-.':'~ : ::~nwere c l ea r Ly able to learn and recall inf ormation..~~el·::I fou r-wee k interval: Th e sub jectsrecalled app r ox Lmat.el y 50percent cf:the hidden ob ject.e-Lc c atLoupairr . Howe v e r . the hypothesisthat,J. r eactLvattont.r eatment du ri n g a retention interva l wo u l dfa cil i t ate rea alI (rom long-termmemoryfo r t:.r ec-- yc J.r-ol d chil d re n;.;a s not supported.
In answer to the question of I-:hl2ther,;:: :.:~ \;a vir:-:;
input inte learnir.; facilitatedacquis it ion an::ieccl I
<')f thehidd e n object- locatiJll pairings, the La ter actfon between source of ccnt r c l and tria l approa ch e d significance. Input intothe Luar n Lnq materia l , and
elaborateth e l ...Hr.ingmaterLa L, ve r ei:H: ~ ~'=C~ :.c ,and perhaps evendctrLme n t a l,,...itt, thic i:lge grouv'
TheeEfec tc'.f ~ot r. raactLvaticn ~ll ~! :;,.'.: : -:.f con t r o l aer e examd aed todetermi n e ',;h c t t n ~~.'; ~" ';OI;1:.~
be an i.a t eractLon bet ...een the twove rtabj es. !jorld un d (1987. 1983) argued that both prior kncvl e dqe, 3.:J.d repe ated expocures tothe lear n Lnqmat.e r LaI at r enqthe n the Iinksbetween fe e tu r esinmemory tr a c e s . :'~.e
'0
___hou l d have»o rked!::i gf:!';.b.e r l.:l =aci.::"';.3.te re ca l ;, Thi z cle a rly •....as notthe cas e•
Reactiva tiondidnot =acilitat e reca ll o~
informat ionfrom long-termmemor y . Res ults shcve d no zigni fi c.3 nld Lff erenc c bet·...een t hethre etreatc.ent c ondttto nc(i.e., rea c t r-..ation, partLaler e a ctivatd on, andcont r o l ). The reare severa l ways to .interjr et.thiz findi ng . First, the~xper iment er '.!ip r esen c ec-ne Lde cf
EOI:..11 cucfec es . Itmay abo have interfered:.,'i ththe or igina l memorytr a c e of theacquis i t ion materiaL,
The reac tiva ti on tr e a tmen t wasgi ven inthe dayca r e c entre , whe r e the experimente r was oftens eenc y all ch ildren. When he vent to test subs eq uent s ubj ect.sat
the initia: le a r r.in g fcr the subjec ts tested .;~:.- ~ :' e r , ev IJonc cJ l::r themany chdLdr en who askedtc ~;~; the
c eel. }. Th·.' :-=,:n~:ingmate r La l.aa y Lav e Seen r ca ctLvate d tor subject s in all condit ions. Bol le r et al .:19 90) stated thatinformat i on ac quir e d afte r ini t ial :rai ni ng may bee orne associat e dwi t h the ori gin al memoq' tr ac e . Suchin f o r mat i o n ma y includeseeing th eexp erinenter in
11
eeeveee the ne wtrace andtheo:-ig inal trac e. ;oll...r..:t al• arguedt~at the Loriqer-the r etenttcntne erv a t•the mor a oppo r ttmi t:'es for ~~.iz ':.0cc cu r.
a
th L : alterationhap p e n:),thenan ath ~L-w it~-:ff" ct:'\';, rea ct.Lvatc r.su c h J.S~howingthe cb jectz uae d::1.an object-locationpairing task, mightbe unable:;1ac ce ccr eactIvatcdthe or :';:",.a l memorytr ace tor .:1.11
conditions the r e b y reducingaccess to thetr ace. then the sight ofth e exp e ri me nt erccuLdaccount ~C~ t herc being'no differencebetween the thrn treatmer;':.
.\ se c-cnd':'01terpretatic••t~c c ccunt ~J r :..'~.i"
familiar::oom in the dayear e was usedto make ':.~. ~chil d feel more ccnrc r eebt e• Del.c a che, o::azsidl"nr..!.:;~ o ~ n (1 98 5) foundnoper f o r manc e dif fe r ence betwe en con d:..: c t i ::.;,l.I.:c h tests in theheme :~J,.:nil: J. r ~~ ':. ':. i :".':l: and
:ec r, :;:"':.~.e:'Jb:;rc-:t:: r equLa r Ly ever the fcui-',:.;:~k
rete ntion Lnt erv a lshich ...eactivated the ;;>ah ::';-.;:: , Ma v i n; and ct,oi (l ~ 72j st a ted tha t ther~zpo ,,::o:aa s the necenaa r y andsutHcient reactivator. It :;,a, c et~.a t all subjc ctzhad
n.i.=
reac tiva cLc r; tr eat ment . reducinq any ddf fe re ncec be tv eentre at ment c cndrticnc . :f t!-.i s study had be en done in as chcc l, aswas th eH:c ':~ n g et~h<:contr c; con dLtion vcul d not have se e n the
e
xperimen t e r 'Jn ti l ~inal tes t i ng, ;';3well ,a
r; ,;scho ol or labth e sub j e c tswouldnothave routinelybeen inthe exp er imentaI room.Athi r dposa Ibl e in t e r p r et a t i o n isba s ed :0the
trea t ment. :,It;-.,ou<,; ~.Ho'Jir.; and::hc i ~1::'7 :; ctatedthat
bec a us ethedesi g n is analogo us to the infant r es ea r cb onreactiv at tcn. acvee-cotlLerand Hayne(1987; USE: d a complex stLmulus and a z::'ngle response, The r e sponae in tnt)pres ent; ctudy vas comp l e x and might havepr cvLded
acqu isitionsraae• ae vee-cottierand :3.gen
t:: .: : l )
arg ued that thetever the~·.:.n.1)erof ,;,·ol.t e:.t u3.1=ut'~ 3t ac qu i s i ti on , the cmaller tbepo::::i!;..i~:':i' :'~.at':b:lu g c L at t r i b u t e ....il~be accessedat ~ina~ teetLnj. ::;ybo:ther e'oI-l're r.: t enoughcont e x t u al cue sin thepr e sen t.
study. Eac h rc omuaed had enouqhLccatLc ne tcr. Ld et!".~
bri9ht~j'colo ure d clcv-,onthe to,,' rather lb.:.
locationa auehaa 'behind3chair ' cr 'un d er :1cus hi cn' mig h t have increasedthe conte xtual cue s . Also,gcvee- Collierand Hayne ~1917) emphazLa cd 'ihe imp'')t';:H•.:'! .f ...
dfstIn ctIve setti ng~orreacttva tto n tobe efrectrve.
:': ;;-..:1j' !.~~"ha':a.ncr e H::::i:.:':i":':.:c·:.ti:1;; :.;;:. ~:,:,;;:::,)r 1.
Atea: ti,,:!~iontre atc.e n t.::-,ig!".':ther; ~.3.v ,:, ;;J,lL" ~:,: :"c:l glj'
toe:!.'; :;'.::•.
nu ll find i n gs is thelength of rete nti on tnt evv at s. The ret enti oninter vals be twe en ac quis i t i onand
reactiva tion , andbet weenrea cti va t i onand b~; -t er:tl rete ntion, dftter ~romtncseused in res e a r ch;:0infa n t ::
three- raont h-ctu rhi.Ld r en=oqet aftcr ') - 1Z:::3j':;
-:.:h ild r'~ n f: ::ge t attc r 14- ::~da y:: (Hi l l at el . 19 Se) . 1\rea cttvattcn tr ea t.nent ....ithin':.',.1'0ve eks of f:rgettin;, th~Y'ctated,....i l1:1.11 0101f'-11 1ac cesn':.0 thecr ~;;: :1. a l ne n.or; ':.race , zec oe rcbers whos t udyc c hccl>aqe:hildrer;
(:10'11:1.9 I;.Choi, D72; Hovinget; al., 137 ::) emt-:;la
re ac tivaticnmay no t l.cvo Seee ~ong~nou ;h tc .r.sure th a t ther ehad bee n zuffic ien':. fo rgettingfo r reactiva tion to be r.fIective. '!'~e~i :ne f~r io dbetveen react ivctLca ari dfin al tes ti ngmayals o not have been
tc te,":". ;::::t ·ff,.";t i '.-",,
re acttvct tcnwasnot ef fe c tiv e in facilitatin;re c a llin threeeyea reold chil d ren.Ther e seems to be ~ig:,~ f i cant evi dence inth e litera ture that reactivationis t!ffJ C' ti'J ~ '~ith inb n ts(t! ,:;t" acv ee-ccttIe r ~Ealne,
preschoo lchil d r en.. Sue r. res e a r ch :r.:l\.:.~J::l02t " ~::l.:.ne~~
thecubjects a r e seeni:..~, :,-b .;;",t~ :':-. g , J.cc o ·..:r.~ : ;;.gicr c cntinuousreac tive t Lon, :.;;,l;.;1",';-:1 ares pcno e :~ :l .t.:l th an a stirnul ucis used astae rea ctivatcr. as :;uC;; '::t·~:\bj'
:;ignifi':::Ir.l .
Th e questicn or zhethe r or not int:'\ll Lr. tc:'~ a: nij) 'J
al s o e x amined. Th e l ack -:.~::i g n if i:<:l n t ,Ef~·;:., :: ces
:0
bychoo:::ingwhichobject to hide in a atven ::;ati on , andth isiT,a] not havebeend.ict Lncten ouq t. ~::~ .~ ':h'"
ex peri mente r - gen er at edcondition. :f :;ubj <?':':: in ';.h'~
ccdu r-dant . Each :hi~..!'.... auldhave been r erra ndec ,jf dif f e r en t cbje ctelc c ation pairings, arid anyd:~ ~e renc:es fo und couldnot ~,aveconclusively
c
eenattrIbc t ed to the efI cct scf reccttve tion sinc e theree c ti.vattcr, vouldnet ha ve Leen c onaf c t.ent acr cs c pa rt icipant c .Th<:qacs ticn of:vhetr.e r cr:-.:t ;erformir.; 1task
,;ti ::
-mrecc lved . ccrae l; andlien. ::99 3) 3r;·.:. ~ dtha t there.:.,;; nc ton efLt t,j beir.q ':'n ;·o>.-.;-Jir.lea; r.;' ;-.9·.~. e .nate ria l . Bol leret al. (1 9 9 0 )ar q-...ed that eae atveactions . aoser.ba um(1 9 57) a r qued that observ:::; a task
hidd en-object lcc attcnsfa cil it a t;~:; recc l L. ':':.:
re s e arch to determine:'f having input ir.tothe ~eal:ni ng
mate r Lcl.
task cu cbas tlle one r equfred in th i :::; stu dy. ::~ \oIcve r, based on the vcrk of Flavell et 301. (l~7S) and :'~mp el:::;
et 31. :ln 7 ),th l'~ e- 1 e3.r -ol d:::;cho u l d be a bIe','; perf or m the pres enttas':• Itappcar ed .;lur in gthe p rec ect experLaent.tha t thecubject c under stccd '.he rcquLr cmentc cf the task. Their rec sLlof about ::'0 per ce n t :If t he
lac}; o~ di f fe r enc e may morc l Lkelybe due t.o;.:acl~cf dizt ir. :::tiven e:::;between th e ta o];dema nds tha n-:: <ll a ck of undcrstand Inq of the task.
Sub jec t :::;in th e se If- \;en era t e d cond iti o n:.act thc opportunity tous epri or knowledge le a rn e d thr::u g hthc Li
bfdd en b~1:. ir.da cus hionc) :';.;--;.31 Le tha'; '.!-. ,~:l'~:' .
not seemto aut ornatic alLyO~·deliberatelyuse :;.st r a te r;t1 such asel abor atLcntc help thcrrcc l v e s J.cc.ju i~'., '.~. C lea rnd nq material.
Th~in t e r a cti onbe t ween c cu rce ct c.a. tro'; cnd trLa l IS
incre ac e in error: ~':; l: the zel~~gen'O"rated,;;c:l.d:''::'or..
Although net toomuch can bema d ec~ th is ,the fec r e as e inper Eo rmance in the :elf-generat~d conditiar.vas :ur;~nZ lr.c;. stnc e ~~,izcondition's i:n o wl e dg e
c
as e ·...a:oupposed l yel abc r at ed, th...se ch dLd ren:;ho\,;~dr.ave been ableto retainthe matcriaI ove r ti....e. 1t c:::-:.:::!.p e rha pc
beearne bcr ed with thetaskandput le s s ettor; iat.c r c ca l l Lnq the objectelcc ation.,airi.:-.3:;;. I tsee:':'l::: morc possib le that their knowledge base vas not e l abcr ated and:hectccre a s einr ec et ; cv e r te st trIe l s Lsce l ated to some other factor.
(:':?89) ar que d , len n i r'. ; tc crite ricr. at J.'=r..:iz:'tic :'.:.nd
components of a two-staqe lonq-term retention tes t. uhen oubjeo t s learntheacquisi tLon ma t e ricI t: a str Lnqent crite ri on, it ensures that a lIsubjects le a rn th e material. "t!ong- 'ermret ent Lca , 3.: Hov:.:.;;et al,
cf acme i.;-.forr:.atLcn::-,3.y.:;park r oca l 1of add':"~:'~:•a l Lnt crmct icn . Mu lt i p l e testtrieis,.I n res u tt ~_~
.:h:1I':ge, an Lr.cr eace ':':1 i:l.fo:::nationre c aLlod, :~1
decreasein i:1fo r:nationie cal lad. !:-.this.;':;.: . ~ . fer thr eeryea rrcl ds the rc aa s a.;:1ight :'r;':1' .:.-11$'::':'v",: tect trte l e.:~i...formaticr,::e ~:::11 1",d ~o;,: ~he~:·:P"'t"::'::-.r.tc r-
theself -g~ r.el."3.toJdcond tticn , :1ore :.:If',,. -':e r ;r..-tentic..
between thesel~-and expe rimente re qen er atezlccad Ittcnc.
;,a Lnq l c t e st wcul drio t t.avc sbcvn'ihd c .:tppt".:.J.:;~t ; sign if icantdff fe r ence and ic net. nece s anrl l y iadfc ativo
with t.h r ee- ryea rrol d aubjectz was app r op riate• xec e ar cb :.Jitr.pr ea chcc Le r a has tendedto r eLy cr; r.ar eat ~·:I-r..rt.:;
or episodicmemories of event s in ',;hic!1the :u);; e c t::
,~t:1.1. ;1:) 72) and t.emp cc o ct d . (1~ ':' 7) 3.r g e-s:.:!.a r e ';ap 3. l:.~::~~ h:'dir.;; and.:;eekir. ;. ,:,~.e}· seem to beabl eto
ce e ot to !li de t~. " obje c t a, t? Le requir ed t cre-.e mber thehidi r.; l c c aticnc, and t:: ae arct; fer cbje c';c,:r.e ~·
)"..:'1:10n'1pericda of ~im e. sec c nd , t~. e ~3.ck:: .:;i 9 ni~iC'3ntl:1a1:-,eftects01:inte r ac t i on.:ma y r.ave be en
empirica lev id en ce tojustIfy furthe r r esea rcr. cn th e
<:!f~<:t::of rocctivctionandccurccof :on t :- ,;: ~ :':.
rel ati on to tcna -te nn reter. ttcn fo r pr-e sc hooIe rs, To det c rrm ne if reac tivatLc nand Ln put..intc lea:- :::::.-,;;
