ProfessorPaulBloom:
So,mostofwhatwedothesedays–ourmethods,ourtheories,ourideas–areshaped,tosomeextent,byPiaget'sinfluence.Andso,whatIwanttodoisbeginthisclassthat'sgoingtotalkaboutcognitivedevelopmentbytalkingabouthisideas.Hisideawasthatchildrenareactivethinkers;they'retryingtofigureouttheworld.Heoftendescribedthemaslittlescientists.Andincidentally,toknowwherehe'scomingfromonthis,hehadaverydramaticandambitiousgoal.Hedidn'tstartoffbecausehewasinterestedinchildren.Hestartedoffbecausehewasinterestedintheemergenceofknowledgeingeneral.Itwasadisciplinehedescribedasgeneticepistemology–theoriginsofknowledge.Buthestudieddevelopmentoftheindividualchildbecausehewasconvincedthatthisdevelopmentwilltellhimaboutthedevelopmentofknowledgemoregenerally.There'saverysnootyphrasethat--Idon'tknowifyoueverhearditbefore.It'sagreatphrase.It's"Ontogenyrecapitulatesphylogeny."Andtheideaofthis--Whatthatmeansisthatdevelopmentofanindividualmimicsorrepeatsdevelopmentofthespecies.Now,it'sentirelynottrue,butit'sabeautifulphraseandPiagetwascommittedtothis.Hewasveryinterestedinsaying,"Look.We'llfigurehowakiddevelopsandthatwilltellusaboutthedevelopmentofknowledgemoregenerally."
So,Piagetviewedthechildasascientistwhodevelopedthisunderstanding,theseschemas,theselittle,miniaturetheoriesoftheworld.Andtheydidthisthroughtwosortsofmechanisms:
assimilationandaccommodation.So,assimilationwouldbetheactofexpandingtherangeofthingsthatyourespondto.Piaget'sexamplewouldbeababywho'susedtosuckingonabreastmightcometosuckonabottleoronarattle.That'schangingthescopeofthingsthatyourespondto.Accommodationischanginghowyoudoit.Ababywillformhismouthdifferentlydependingonwhathe'ssuckingon.Andso,theseprocesseswhereyoutakein--I'mgivingthisinaveryphysicalway,butinamorepsychologicalsenseyouhaveawayoflookingattheworld.Youcouldexpandittoencompassnewthings,assimilation.Butyoucouldalsochangeyoursystemofknowledgeitself–accommodation.AndPiagetarguedthatthesetwomechanismsoflearningdrovethechildthroughdifferentstages.Andhehadastagetheory,whichwasquitedifferentfromtheFreudianstagetheorythatwehavebeenintroducedto.Sohismethodsweretoaskchildrentosolveproblemsandtoaskthemquestions.Andhisdiscoveriesthat--theydidthemindifferentwaysatdifferentagesledtotheemergenceoftheStageTheory.
So,forPiaget,thefirststageisthesensorimotorstageorthesensorimotorperiod.Forherethechildispurelyaphysicalcreature.Thechildhasnounderstandinginanyrealwayoftheexternalworld.There'snounderstandingofthepast,nounderstandingofthefuture,nostability,nodifferentiation.Thechildjusttouchesandsees,butdoesn'tyetreason.Andit'sthroughthisstagethatachildgraduallycomestoacquireobjectpermanence.
Objectpermanenceistheunderstandingthatthingsexistwhenyounolongerseethem.Sothoseofyouinfront,you'relookingatmeandIgo[ducksbehindlectern].Itoccurredtomeit'dbeagreatmagictrickifIthenappearedinback.Butno,I'mjusthere.That'sobjectpermanence.IfIwentunderhereandthenthepeoplesaid,"Wherethehelldidhego?
Classisover,"thatwouldshowalackofobjectpermanence.So,adultshaveobjectpermanence.Piaget'sveryinterestingclaimisthatkidsdon't.Beforesix-month-olds,Piagetobserved,youtakeanobjectthekidlikeslikearattle,youhideit,youputitbehindsomething,it'slikeit'sgone.Andheclaimedthechildreallythinksit'sjustgone.Thingsdon'tcontinuetoexistwhenI'mnotlookingatthemanymore.Andsohenoticedthey--they'resurprisedbypeek-a-boo.AndPiaget'sclaimwasonereasonwhythey'resurprisedatpeek-a-booisyougo--youlookatakid,thekid'ssmilingandgo,"Oh,peek-a-boo,"andyouclose--andyoucoveryourfaceandthekidsays,"He'sgone.""Peek-a-boo.""Oh,thereheis.He'sgone."Andyoureally--That'stheclaim.
Piagetalsodiscoveredthatolderchildrenfailatataskthat'sknownastheA-not-Btask.AndPeterGrayinhispsychologytextbookreferstoitasthe"changinghidingplaces"problem,whichisprobablyabetternameforit.Andhere'stheidea.Youtakeanine-month-oldandforPiagetanine-month-oldisjuststartingtomakesenseofobjectsandtheirpermanence.Youtakeanobjectandyouputithereinacupwherethekidcan'tseeit,butit'sinthecup.Sothekid,ifyouwerethekid,willreachforit.Youdoitagain,reachforit.Youdoitagain,reachforit.That'spointA.Thenyoutake--youmoveitoverhere.Piagetobservedkidswouldstillreachforthis.It'slikethey'renotsmartenoughtofigureoutthatit'snotthereanymore,eveniftheyseeitmove.Andthiswasmoreevidencethattheyjustdon'tunderstandobjects,andthatthisthingtakesalotoftimeandlearningtodevelop.
Thenextstageisthepreoperationalstage.Thechildstartsoffgraspingtheworldonlyinaphysicalway,inasensorimotorway,butwhenhegetstothepreoperationalperiodthecapacitytorepresenttheworld,tohavetheworldinsideyourhead,comesintobeing.Butit'slimitedandit'slimitedinacoupleofstrikingways.Onewayinwhichit'slimitedisthatchildrenareegocentric.Now,egocentrismhasameaningincommonEnglishwhichmeanstobeselfish.Piagetmeantitinamoretechnicalway.Heclaimedthatchildrenatthisageliterallycan'tunderstandthatotherscanseetheworlddifferentlyfromthem.So,oneofhisdemonstrationswasthethreemountainstask.Wehavethreemountainsoverthere.Youputachildononesideofthemountainsandyouaskhimtodrawit,andafour-orfive-year-oldcandoiteasily,butthenyouaskhimtodrawitasitwouldappearfromtheothersideandchildrenfindthisextraordinarilydifficult.Theyfinditverydifficulttograsptheworldasanotherpersonmightseeit.
AnothersignificantfindingPiagethadaboutthisphaseofdevelopmentconcernswhat'scalled"conservation."Thenotionofconservationisthatthere'swaystotransformthingssuchthatsomeaspectsofthemchangebutothersremainthesame.So,forinstance,ifyoutakeaglassofwaterandyoupouritintoanotherglassthat'sshallowortall,itwon'tchangetheamountofwateryouhave.Ifyoutakeabunchofpenniesandyouspreadthemout,youdon'tgetmorepennies.Butkids,accordingtoPiaget,don'tknowthatandthisisoneoftherealcooldemonstrations.Anyofyouwhohaveaccesstoafour-orfive-year-old,[laughter]asiblingorsomething--Donottakeonewithoutpermission,butifyouhaveaccesstoafour-orfive-year-oldyoucandothisyourself.Thisiswhatitlookslike.Thefirstonehasnosound.Thesecondoneisgoingtobesoundthat'sgoingtocomeonattheend[playsvideo].Butthere'stworowsofcheckers.Sheasksthekidwhichonehasmore.Thekidsaysthey'rethesame.Thenshesays--Nowsheaskshimwhichonehasmore,thatorthat.Sothat'sreallystupid.Andit'sanamazingfindingkidswilldothatandit'sarobustfinding.
Here'sanotherexample.So,they'rethesame[tapeplaying].So,it'sacoolfindingofthatstage,suggestingalimitationinhowyoudealandmakesenseoftheworld.Thenextphase,concreteoperations,fromseventotwelve,youcansolvetheconservationproblem,butstillyou'relimitedtotheextentyou'recapableofabstractreasoning.Sothemathematicalnotionsofinfinityorlogicalnotionslikelogicalentailmentarebeyondachildofthisage.Thechildisabletodoalot,butstillit'stosomeextentstuckintheconcreteworld.Andthenfinally,ataroundagetwelve,youcouldgetabstractandscientificreasoning.AndthisisthePiagetiantheoryinverybriefform.
Now,PiagetfaredalotbetterthandidFreudorSkinnerforseveralreasons.Onereasonistheseareinterestingandfalsifiableclaimsaboutchilddevelopment.Soclaimsthat--aboutthefailureofconservationinchildrenatdifferentagescouldbeeasilytestedandsystematicallytested,andinfact,there'salotofsupportforthem.Piagethadarichtheoreticalframework,pullingtogetherallsortsofobservationsindifferentways,wrotemany,manybooksandarticlesandarticulatedhistheoryveryrichly.Andmostofall,Ithink,hehadsomereallystrikingfindings.BeforePiaget,nobodynoticedtheseconservationfindings.BeforePiaget,nobodynoticedthatbabieshadthisproblemtrackingandunderstandingobjects.
Atthesametime,however,therearelimitationsinPiaget'stheory.Someoftheselimitationsaretheoretical.It'saninterestingquestionastowhetherhereallyexplainshowachildgoesfromaconcretethinkertoanabstractthinker,orhowhegoesfromnothavingobjectpermanencetounderstandingobjectpermanence.There'smethodologicallimitations.Piagetwasreallybigintoquestionandanswer,butoneproblemwiththisisthatchildrenaren'tverygoodwithlanguage,andthismightleadyoutounderestimatehowmuchtheyknow.Andthisisparticularlyaproblemtheyoungeryouget.
Methodologyisgoingtoloomheavyinthediscussionofanyscienceandthatincludespsychology.Often90%ofthegameisdiscoveringaclevermethodthroughwhichtotestyourhypotheses.We'regoingtotalkalittlebitaboutthatregardingbabies.I'llgiveyouanotherexamplefromaverydifferentdomain.Therewasasetofscientistsinterestedinstudyingtickling.So,whenyouticklesomebody,underwha
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