Infants’sensitivitytocostsandbenefits

JessicaSommervilleUniversityofWashington

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• PartI:Infants’registrationofthecostsinothers’action

• PartII:Infants’useofcostsandbenefitstoguidetheirprosocial behavior

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Physicaleffortascost

• Minimizingrelianceonenergeticresourcesisanimportantpartofsurvival

• Lawofleasteffort• Non-humananimalsengageincost-benefitdecisionmakingwhereeffortiscalculatedasacost

• Adultsseektominimizephysicalandcognitiveeffortandengageincost-benefittradeoffs

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Doinfantsregistercosts?

• Evidenceofcostregistrationandminimizationininfants’ownbehavior– Infantspreferlighttoveryheavyblocks

• Evidenceofcostregistrationinother’sactions– Infantsexpectefficiencyinothers’action

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Doinfantsregistercosts?

Courtesy of Proceedings of the National Academy of Science. Used with permission.Source: Skerry, Amy E., Susan E. Carey, and Elizabeth S. Spelke. "First-person actionexperience reveals sensitivity to action efficiency in prereaching infants." Proceedingsof the National Academy of Sciences 110, no. 46 (2013): 18728-18733.

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Registeringeffort-relatedcosts

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Registeringeffort-relatedcosts

• 12-month-oldinfants(N =23)

• EEGturn-takingprocedure:– Action&Observationtrials:• 70g.,470g.,770g.

– Baselinetrials• Checkerboard

Upshaw,Bernier&Sommerville(2015).DevelopmentalScience.8

Registeringeffort-relatedcosts

• Lookedatsuppressionofsensorimotoralpharhythm(muattenuation)

• Atrest,sensorimotorneuronsfirespontaneouslyinsynchronywhichleadstolargeamplitudeEEGoscillationsinthealphafrequencyband

• Whensensorimotorcortexisactivated(viaactionexecutionorobservation)thereisadecreaseinthepowerofsensorimotoralphaoscillations

• Measureofsensorimotorcortexactivation

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Registeringeffort-relatedcosts

• Gripstrengthassessment– Infants’maximumgripstrength

• Alsomeasured:– Infants’weight– Motorskillschecklist– Frequencyofblockliftsintask

Upshaw,Bernier&Sommerville(2015).DevelopmentalScience.10

SensorimotorAlphaSuppressionduringObservationofBlockLiftsandGrip

Strength(byblockweight)

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0.21

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Changefrom

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ChangesinSensorimotorAlphaSuppressionduringObservationofLifting

byGripStrength

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Infants’registrationofeffort-relatedcosts

• Activationofsensorimotorcortexduringobservationofweightblockliftsvariesasafunctionofblockweight– Recognitionofthedifferentialdegreesofeffortassociatedwithliftingblocksofdifferentweights

• Infants’abilitytomakethisdistinctionistiedtotheirownstrength– Strengthlikelygatestheirexperienceliftingheavyobjectswhichmayhaveimplicationsfortheirabilitytorecognizeeffortassociatedwithobjectsofdifferentweights

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• PartI:Infants’registrationofthecostsinothers’action

• PartII:Infants’useofcostsandbenefitstoguidetheirprosocial behavior

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Prosocial behavior

• Infantsarehighlyprosocial• Twoquestions/debates:–Whendoesprosocial behaviorbecomeselective/strategic?• Earlyorlate

–Whatistheunderlyingmotivationforprosociality?• Needbased(empathicconcern),socialaffiliation,goalcompletion,etc

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Prosocial behavior

• Impactofcostsoninfants’prosocial behaviorisnotwellstudiedorunderstood– Personalcosts:mixedevidence– Energetic/physicalcosts:understudied

• Willanticipatedphysicaleffortinfluenceinfants’prosociality?

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Effort-relatedcosts&infants’helpingbehavior

• 18-month-oldinfants(N=48;24/condition)• Trainingphase:infantsliftincreasinglyheavyblocks(170g.;1970g.to2720g.)

• Testphase: experimenteronoppositesideofroomneedsblocktocompleteatower– Loweffortcondition:lightestblockleftbehind(170g.)

– Higheffortcondition:heaviestblockinfantcanliftleftbehind(1970g.– 2720g.)

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Effort-relatedcosts& infants’helpingbehavior

• Codedblockretrievals– carryingblocktoexperimenter

• Recordedinfants’walkingexperience(monthswalking)– Carryingaheavyblockacrossaroomismoreeffortfulforlessversusmoreexperiencedwalkers

– Predictedeitheraselectiverelationbetweenwalkingexperienceandblockretrievalsinhigheffortcondition,orastrongerrelation

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Loweffortcondition

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Higheffortcondition

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Infants’rateso

fblockre

trievals

X2 (1,N =48)=4.09,p =.043,ø =.29

• Walkingexperiencesignificantlypredictedinfants’blockretrievalsinthehigheffortcondition,OR =2.12,p =.016,(95%CI1.15- 3.90),butnottheloweffortcondition,OR =1.10,p =.72,(95%CI.67– 1.81).

Infants’blockretrievals

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Effort-relatedcosts& infants’helpingbehavior

• Infantsarelesslikelytohelpunderhigheffortconditions– Thefactthatinfantscanliftthetargetblocksuggeststhatitiseffortnotabilitythatgovernstheirperformance

• Costsoperateatbothan“objective”level(heavyblocksaregenerallyhardertocarry),anda“subjective”level(exactcostsarefurtherdefinedbyindividualdifferences;e.g.,walkingexperience)

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Intrinsicbenefits&infants’helpingbehavior

• Isinfants’willingnesstoengageinhigheffortprosocial behaviorinfluencedbythemotivationalbenefitsofprosocial responding?

• Earlyprosocial respondingappearstobeimmunetoextrinsicrewards

• Intrinsicrewards?• Infantspossessaffiliative biasesforsimilaror“ingroup”members– Functionalconsequences:importantforculturallearning

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Theimpactofbenefitsoninfants’helpingbehavior

• 17.5-month-oldinfants(N=56;28/condition)• Training:– Infantchoosesoneoftwotoys– Experimentersharestheirtoypreferenceordoesnot

• Testphase:experimenteronoppositesideofroomneedsblocktocompleteatower– Forinfantsinboththesharedornon-sharedpreferenceconditions2220g.blockisleftbehind

• Post-testphase:infantsencouragedtoliftincreasinglyheavyblocks(2220g.,2570g.,2720g.)

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Theimpactofbenefitsoninfants’helpingbehavior

• Codedinfants’blockretrievals• Recordedinfants’walkingexperience(monthswalking)

• Investigatedhelpingasafunctionoftheresponseperiod– Firsthalfvs.overall– Earlydifferencesthatattenuateovertimesuggestdifferencesindegreeofmotivationtohelp

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Infants’rateso

fblockre

trievals

X2 (1,N =56)=4.67,p =.031,ø =.29

• Walkingexperiencesignificantlypredictedinfants’blockretrievalsinthenon-sharedpreferencecondition,OR =1.88,p =.033,(95%CI1.05- 3.36);butnotthesharedpreferenceconditionOR =1.45,p =.151,(95%CI.87– 2.41).

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Infants’blockretrievals:Firsthalf

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Infants’rateso

fblockre

trievals

X2 (1,N =56)=1.91,p =.158,ø =.19

Infants’blockretrievals:Overall

00.10.20.30.40.50.60.70.8

Sharedpreferences Oppositepreferences

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Intrinsicbenefits&infants’helpingbehavior

• Infants’willingnesstoengageinhighcosthelpingisaffectedbyintrinsicmotivationalfactors– Infantsaremorelikelytocarryaheavyblocktohelpsomeonewhosharestheirpreferences(versussomeonewhodoesnot)

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Cost-benefittradeoffsininfants’helpingbehavior

• Expandingthescopeofbenefits: Richvs.poorexperimenters– Youngchildren(3- and4-year-olds)sharemorewithrichversuspoorrecipients;affiliative biastowardrichindividuals

– Receivepriorinformationthatoneactorhasalotofresourcesandoneactorhasfewresources

• Equaleffortvs.unequaleffort(shortvs.longwalk)

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Infants’blockretrievalsbywealthandeffort

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Infants’blockretrievalsbywealthandeffort

n=16 n =7

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Equaleffort Unequaleffort(Rich>poor)

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Implicationsforinfants’prosocialbehavior

• Cost-benefitanalysesunderlieinfants’helpingbehavior

• By18monthsinfants’prosocial behavioris“strategic”inthesensethattheyappeartominimizecostsandmaximizemotivationalbenefits

• Underlyingmotivationtohelpisinfluencedbyatendencytowanttoaffiliatewithcertainindividuals

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• PartI:Infants’registrationofthecostsinothers’action

• PartII:Infants’useofcostsandbenefitstoguidetheirprosocial behavior

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Futurequestions

• Identifying“currency”–Whatcountsasacostandabenefit?

• Howarecosts“read”?– Somecostsmaybeobviousfromthegetgo;othersexperientiallyderived

• Doinfantshaveacategoryofcosts?

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Acknowledgements

TheJohnTempletonFoundation

NICHD1R01HD076949-01

Images of Kayla Upshaw, Miranda Sitch and Elizabeth Ake removed due to copyright restrictions. Please see the video.

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