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DOEQUIVALENCECLASSESMEDIATEEXTENSIONS OFSTIMULUSFUNCTION? By MANISHVAIDYA ADISSERTATIONPRESENTEDTOTHEGRADUATESCHOOL OFTHEUNIVERSITYOFFLORIDAINPARTIALFULFILLMENT OFTHEREQUIREMENTSFORTHEDEGREEOF DOCTOROFPHILOSOPHY UNIVERSITYOFFLORIDA 2000 TABLEOFCONTENTS ABSTRACT '» GENERALINTRODUCTION 1 EXPERIMENT1 11 Method 12 Results 17 Discussion 37 EXPERIMENT2 42 Method 45 Results 48 Discussion 66 GENERALDISCUSSION 70 APPENDIX:INSTRUCTIONS 74 REFERENCES 75 BIOGRAPHICALSKETCH 79 ii AbstractofDissertationPresentedtotheGraduateSchool oftheUniversityofFloridainPartialFulfillmentofthe RequirementsfortheDegreeof DoctorofPhilosophy DOEQUIVALENCECLASSESMEDIATEEXTENSIONS OFSTIMULUSFUNCTIONS? By ManishVaidya May,2000 Chairperson:TimothyD.Hackenberg,Ph.D. MajorDepartment:Psychology Stimulusequivalenceisdemonstratedwhenthefunctionsofstimuli establishedinreinforcedconditionaldiscriminationtrialsareshowntobe interchangeableinunreinforcedconditionaldiscriminationtrialsinvolvingthesame stimuliinnovelconfigurations. Althoughmuchhasbeenlearnedaboutequivalence relations,thepreparationstypicallyusedhavenotallowedapreciseunderstanding oftherelationshipbetweentrainedandderivedconditionalrelationsortheroleof equivalenceclassesinmorecomplexbehavioralrelations. Thepurposeof Experiment1 wastoattemptamorepreciseunderstandingoftherelationship betweentheacquisitionoftrainedconditionaldiscriminationsandtheemergenceof untrainedconditionaldiscriminations. Sixundergraduatestudentswereexposedto 18conditionaldiscriminationtrialtypesdesignedtotrainandtestfor33-member equivalenceclassesfromthebeginningoftheexperiment. Oncechoiceswere stable,thecontingenciesfor2of6trainedrelationswerereversed. Theresults showedthattherewasalagbetweentheacquisitionofthetrainedconditional relationsandtheemergenceofderivedconditionalrelationsthatdefineequivalence classes. Inaddition,thereversalofcontingenciesforasubsetofthetrainedoriginal relationsproducedchangesonsomeofthederivedconditionaldiscriminationsbut notothers. Thesedatasuggestedthat(a)thebehavioralprerequisitesfor conditionalrelationsandequivalencerelationsarenotidenticaland(b)thedifferent stimuluscontrolrelationsthatdefineanequivalencerelationcanvaryindependent ofoneanother. ThepurposeofExperiment2wastoascertaintheroleof equivalenceclassesintheextensionofstimulusfunctionsacrossclassmembers. Threeundergraduatestudentswereexposedtotheconditionaldiscriminationtask describedabovewithasuccessivesimplediscriminationtaskinterlacedthroughout thesessionfromthebeginningoftheexperiment. Theresultsshowedthat extensionofstimulusfunctionwassometimes(a)observedpriortothedevelopment ofequivalencerelationsand(b)notobserveddespitetheformationofequivalence relations. Thesedatasuggestthatequivalenceclassesareneithernecessarynor sufficientfortheextensionofstimulusfunctions. Takentogether,theseresultscall intoquestiontheassumedintegratednatureofequivalencerelationsandtheirrolein theextensionofstimulusfunctions. iv GENERALINTRODUCTION Someoftheoldestquestionsinpsychologypertaintoreferenceand meaning. How,forexample,dosymbolscometorepresent,orreferto,other figures,objects,orevents?Earlybehavioristaccountssuggestedsimplesubstitution astheanswer. Asymbolwassaidtomeanthesamethingasitsreferenttothe extentthatsymbolandreferentproducedthesamekindofbehavior. AsWatson (1924)putit: [w]ordsnotonlycananddocalloutotherwords,phrasesandsentences,but whenthehumanbeingisproperlyorganizedtheycancalloutallofhis manualactivity. Thewordsfunctioninthemannerofcallingoutresponses exactlyasdidtheobjectsforwhichthewordsserveassubstitutes(p.233). Althoughcurrentapproachesnolongerassume thatreference-likerelationsinvolve thecompletesubstitutabilityofsymbolsforobjectsorevents, thefundamental problemofreferenceandmeaninghasscarcelybeenresolved. Thekeyissue,as Watsonrecognized,lieswiththeextensionofstimulusfunction,orthe circumstancesinwhichaneutralstimulusmaycometofunctioninamannersimilar toanalreadyestablishedstimuluswithoutdirecttraining. Someimportantconceptualandempiricaladvancesinthestudyofuntrained extensionsofstimulusfunctionhavecomefromanareaknownasstimulus equivalence(Sidman, 1971, 1994). Briefly,researchinstimulusequivalenceis concernedwiththestudyoftheorigin,maintenance,andmodificationofbehavior undercontrolofrelationsbetweenstimuli. Theexperimentalpreparationusedto investigateequivalencerelationsgenerallyinvolvesaconditionaldiscrimination procedureinwhichasubjectchoosesoneofseveralavailablestimuli(called comparisonstimuli)conditionallyuponthepresenceofanotherstimulus(calledthe samplestimulus). Choosingtheexperimenter-designated"correct"comparison producesareinforcingconsequencewhereaschoosinganyothercomparisonends thetrialwithoutreinforcement. Asubjectisexplicitlytaughtseveralinterrelated conditionaldiscriminations(e.g.,givenA1 pickB1,notB2orB3;givenB1 pickC1, notC2orC3)andthentestedfortheemergenceofotherconditionaldiscriminations thatwerenotdirectlytrained(e.g.,givenB1 pickA1,notA2orA3;givenC1 pick B1,notB2orB3;givenA1 pickC1,notC2orC3;andgivenC1 pickA1,notA2or A3). Accurateperformanceonthesenovelconditionaldiscriminations,inthe absenceofreinforcement,issaidtoindicatetheexistenceofanequivalencerelation amongthestimuli(Sidman&Tailby, 1982). Thesestimulus-equivalencerelationsaredefinedintermsof3propertiesthat defineequivalentsetsinmathematics-reflexivity,symmetryandtransitivity(Sidman &Tailby, 1982). Thepropertyofreflexivityisseenwhenasubjectselects comparisonstimulithatarephysicallyidenticaltothesamplestimuli. Forexample, giventrainingtopickA1 givenA1,asubjectpicksB1 givenB1 without reinforcementfordoingso. Thepropertyofsymmetryisseenwhenthesampleand comparisonfunctionsofstimulibecomeinterchangeable. Forexample,givena historyofreinforcementforselectingB1 givenA1 assample,asubjectselectsA1 givenB1 asasamplewithoutreinforcementfordoingso. Thepropertyof transitivityisseenwhenthesamplefromoneconditionaldiscriminationexerts conditionalcontrolovertheselectionofacomparisonfromadifferent,butrelated, conditionaldiscrimination. Forexample,givenahistoryofselectingB1 givenA1 . 3 andselectingC1 givenB1,asubjectselectsC1 givenA1 asthesample. These relationshipsareillustratedschematicallyinFigure1 Thisthree-partdefinitionhasbeenextremelyimportantinestablishingaclear matrixofbehavioraltasksthatcanbeusedtoindicatethepresenceorabsenceof equivalencerelationsamongthestimuli. Asanexample,consideranexperiment reportedbySidman(1971). Usingaslightlydifferenttrainingstructure,a developmentallydelayedsubjectwastrainedtoselectapictureofacat(B1)given thespokenword"cat"(A1)andtoselectthewrittenwordCAT(CDgiventhe spokenword"cat"(A1). Asaresultofthistrainingthesubjectcametorespond accuratelyonotherconditionaldiscriminationsthathadnotbeendirectlytrained. Forexample,itwasfoundthatthesubjectcouldnowselectthepictureofacat (B1)giventhewrittenwordCAT(CDasastimulusandselectthewrittenword CAT(CDgiventhepictureofacat(B1). Sidman(1971)concludedthat,byvirtue oftheconditionaldiscriminationtraining,thestimulihadbecomesubstitutableor "equivalent"withinthecontextoftheconditionaldiscriminationprocedure. Animportantfeatureofthesestimulus-equivalenceclassesisthe demonstrationthatstimulithatbecomeequivalentinthecontextofaconditional discriminationtaskcanalsobecomeequivalentinothercontexts. Basedonthe observationthatstimulusfunctionsextendacrossmembersofequivalenceclasses, ithasbeensuggestedthatthecontextofstimulusequivalenceexperimentsmay serveasausefullaboratoryanalogueforthestudyofextensionsofstimulus functionsinnaturallanguages,providingapotentialbasisfortheexperimental analysisofreferenceandmeaning(Hayes, 1992;Sidman, 1986). Itisimportantto notethatifthestimulirelatedviaequivalencerelationsdidnotalsobegintoshare ) 4 i i v A1 3> B1 s» C1 -c- <- A LEGEND ^ Trained relations (A1-B1; B1-C1) « Symmetry (B1-A1; C1-B1) > Transitivity (A1-C1 «c_ Symmetrical Transitivity (C1—A1) Figure 1. A schematic representation of the properties that define an equivalence relation. The solid lines indicate trained relations and the broken lines indicate derived relations. 5 establishedstimulusfunctionstheywouldbeoflittleuseaslaboratoryanaloguesof symbolicrelations. Forexample,ifthewords"water,""agua,"and"paanee" enteredintoequivalenceclasseswithoutalsobeginningtosharestimulusfunctions, thentheirbeingequivalentwouldonlybemeaningfulintermsofthederived conditionaldiscriminationsusedtodocumenttheequivalencerelations. Itis, however,preciselytheobservationthatstimulirelatedviaequivalencealsobeginto sharestimulusfunctionsthathassuggestedthatthefunctionsofthestimuliin equivalenceexperimentsmaybelikenedtothefunctionsofsymbolsinnatural languages(Hayes, 1992;Sidman, 1986). Theseobservations,incombinationwiththefactthatequivalenceclass formationhasnotyetbeenreportedwithpreverbalhumansornonhumans (Devany,Hayes,&Nelson, 1986;Sidman,etal., 1982)but(seeSchusterman& Kastak, 1993),haveledmanytoconcludethatequivalence-likerelationsmaybe fundamentallyrelatedtosymbolicorlinguisticfunctioning(Hayes&Hayes, 1989; Sidman, 1994). Ithasfurtherbeensuggestedthatresearchontheextensionof stimulusfunctionviaequivalenceclassesmayyieldsomeinsightsabouthow humanscometobehavesystematicallyandpredictablyinthepresenceof circumstancesthathaveneverbeforebeenexperienced(Hayes, 1992;Sidman, 1986). Althoughsomeresearchhasexaminedtheextensionofrespondenteliciting functions(e.g.,Dougher,Auguston,Markham,&Greenway, 1994)andoperant consequencefunctions(e.g.,Hayes,Kohlenberg,& Hayes, 1991),themajorityof workinthisareahasbeenconcernedwiththetransferofdiscriminativestimulus functions(e.g.,Auguston&Dougher, 1997;Barnes,Browne,Smeets,&Roche, 6 1995;Lazar,1977;Lazar&Kotlarchyk, 1982;Wulfert&Hayes, 1988). The earliestexperiment explicitlyconcernedwithtransferoffunctionandstimulus equivalencewasreportedbyLazar(1977). Adultsubjectswereaskedtopointto eachmemberofseveralpairsofstimuliacrossrepeatedtrials. Twodistinctclasses ofstimuli(roughly,"pointed-tofirst"and"pointed-tosecond")emergedfromthis training. Inthenextphase,thesamestimuliservedassamplesinaconditional discriminationtaskinwhichnovelstimuliwereintroducedascomparisonsin reinforcedtrials. Followingthat,conditionaldiscriminationtrialswerepresentedin whichthenovelstimuliservedassamples("incorrect"responsesduringthis conditionwereremediatedwithdirecttraining). Finally,thesequencetestwas re-presentedwiththenovelstimulitotestfortransferoffunction. Lazar(1977) reportedthat2ofthe3subjectsrespondedappropriately. Thatis,thesesubjects pointedtothenovelstimulusthatwasplacedinthe"first"classfirstandthe "second"classsecond. Thediscriminativepropertiesofthetrainingstimulushad thusextendedtootherstimuliinthesameequivalenceclass. Studieshavealsoexaminedtheextensionofotherkindsofdiscriminative functions. Catania,Home,andLowe(1989)establishedahighresponserateinthe presenceofonestimulus(atree)andalowresponserateinthepresenceofa differentstimulus(astar)ina5-year-oldchild. Theschedulesandstimulialternated severaltimeswithinasessioninamultipleschedulearrangement. Inthenext phase,thesestimuliwereusedascomparisonsinconditionaldiscriminationtrials involvingtwonovelstimuliassamples(awormandablock). Afterseveralsessions ofgreaterthan90%correctmatchesandconsistentratedifferencesinthemultiple schedule,thesubjectwasre-exposedtothemultipleschedulewiththedifference