1 UAA Department of Working Paper
Transcript of 1 UAA Department of Working Paper
1
UAADepartmentofEconomicsWorkingPaper1
Title:IndirectReciprocity,ResourceSharing,andEnvironmentalRisk:EvidencefromField2
ExperimentsinSiberia3
ShortTitle:RiskandReciprocity:FieldExperimentsinSiberia4
Authors:E.LanceHowe1*,JamesJ.Murphy1,2,3,DrewGerkey4,ColinThorWest55 1DepartmentofEconomicsandPublicPolicy,UniversityofAlaskaAnchorage,3211ProvidenceDr.,6 Anchorage,AK99508;2InstituteofStateEconomy,NankaiUniversity,94WeijinRoad,Tianjin,7 China300071;3EconomicScienceInstitute,ChapmanUniversity,OneUniversityDrive,Orange,CA8 92866;4DepartmentofAnthropology,SchoolofLanguage,Culture&Society,OregonState9 University,218WaldoHall,Corvallis,OR,97330;5DepartmentofAnthropology,UniversityofNorth10 Carolina,301AlumniBuilding,ChapelHill,NC,2759911
*Correspondingauthor12
E‐mail:[email protected]
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Abstract1
Integratinginformationfromexistingresearch,qualitativeethnographicinterviews,and2
participantobservation,wedesignedafieldexperimentthatintroducesidiosyncratic3
environmentalriskandavoluntarysharingdecisionintoastandardpublicgoodsgame.Conducted4
withsubsistenceresourceusersinruralvillagesinremoteKamchatkaRussia,wefindevidence5
consistentwithamodelofindirectreciprocityandlocalsocialnormsofhelpingtheneedy.When6
experimentsallowparticipantstodevelopreputations,asisthecaseinmostsmall‐scalesocieties,7
wefindthatsharingisincreasinglydirectedtowardindividualsexperiencinghardship,good8
reputationsincreaseaid,andrisk‐poolingbecomesmoreeffective.Ourresultshighlightthe9
importanceofinvestigatingsocialandecologicalfactors,beyondstrategicrisk,thataffectthe10
balancebetweenindependenceandinterdependencewhendevelopingandtestingtheoriesof11
cooperation.12
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Introduction1
Researchoncooperationandcollectiveactionoftenfocusesonstrategicrisks—thecostsand2
benefitsofcooperatingordefecting—andassociatedfree‐ridingbehaviorinasingledomain(1,2).3
Expectedpayoffsareafunctionofindividualandgroupchoices,andinteractionsaretypically4
limitedtoaproductionorinvestmentdomain.Previousstudieshavefoundthatrewardscan5
mitigatethecostsofcooperation(3,4),punishmentcanincreasethecostsofdefection(5–8),6
reputationscanfacilitatepositiveassortmentamongcooperators(9),andculturalnormsand7
institutionscanstructureincentivesandexpectationsinwaysthatsustaincooperation(1,10).8
Insmall‐scaleresourcedependentcommunities,cooperationcanoftenoccurinmultiple9
domains,suchascontributingtoapublicgood,harvestingfromasharedresource,punishing10
defectors,rewardingcooperatorsorsharingwiththosewhoexperienceahardship(11–13).These11
domainsusuallyinteractwhichreflectsthefactthatbenefitsofcooperationcanextendbeyonda12
singleperiod,domain,orstateofnature.Cooperationmaybepreferredtonon‐cooperation13
preciselybecausefuturestatesofnatureareuncertaininoneormorelinkeddomains.Assuch,14
environmentalrisk—definedasthespatialandtemporalfluctuationsinbioticandabiotic15
componentsoftheenvironmentthataffectaccesstoresources,health,andothermeasuresof16
humanwell‐being—couldincreaseinterdependenceand,asaresult,long‐termsuccessdepends17
uponcooperationinmultipledomains.18
Idiosyncraticenvironmentalriskcreatesuncertaintyaboutfuturepayoffsinacollective19
actionproblem.Individualharvestingsuccessmaybestochastic,harvestedresourcesmayspoil,20
animalsmaydestroystoredfood,oraninjurymaypreventtheindividualfromparticipatingin21
collectiveaction.Insubsistencecommunities,whenanindividualexperiencesahardship,ora22
“shock,”hisorhersurvivaldependsuponthelargesseofothers.Thus,thedecisionsaboutsharing23
subsistenceresourcesmaydependupontheindividual’sreputationforcooperatinginother24
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domains.Althoughenvironmentalriskcanincreasevariationintheproductiondomain,sharing1
amongindividualsandhouseholdscancompensatefortheseshort‐termproductiondeficits,linking2
strategicdynamicsandcooperationacrossthetwodomains(14–17).3
Inthispaperwepresentresultsfromaframedpublicgoodsexperiment,conductedin4
subsistence‐dependentcommunitiesinSiberia,designedtotesthowidiosyncraticenvironmental5
riskinteractswithstrategicrisktoaffectcooperationwithinandbetweentheproductionand6
sharingdomains.Consistentwithamodelofindirectreciprocity, ourresultsindicatethatdecisions7
inthesharingdomainareconditionedonreputationsforcooperationintheproductiondomain.We8
alsofindevidenceforrisk‐pooling,asindividualssharemorewiththoseinneed.Further,when9
reputationsforcooperationextendacrossmultiplerounds,theaidprovidedtocooperators10
increasessubstantiallyandrisk‐poolingbecomesmoreeffective—aresultthathighlightsthe11
importanceoflocalsocialnormswhichemphasizeresourcesharingandhelpingtheneedy(18,19).12
However,therewardsfromsharingareinsufficienttoimprovecooperationintheproduction13
domain.Similarly,wefindcooperationintheproductiondomainisunaffectedbyenvironmental14
riskthatisunavoidable,consistentwiththeoreticalpredictions.15
EnvironmentalRiskandCooperation16
Becauseenvironmentalriskintroducesvariabilityinresourceacquisition,itcanbedifficultor17
impossibleforasolitaryindividualtoconsistentlyacquiresufficientresourcestosurvive.Thus,18
environmentalriskscanaffecttherelativeviabilityofindependentversuscooperativebehavior.19
Previousresearchshowsthatenvironmentalriskaffectscooperationoverrivalrousgoodsinsmall‐20
scale,resource‐dependentcommunities.Intheoreticalstudies,environmentalriskoruncertainty21
canincreaseordecreasecooperationinsocialdilemmas(20,21).Experimentalstudiesgenerally22
findthatincreasingthevariabilityofreturnstoeitherthegrouporprivateaccountreduces23
5
cooperationintheriskierdomain(22–24);incontrasttheidiosyncraticshockinourdesignis1
unavoidable,itaffectsboththegroupandprivateaccountsequally.2
Althoughenvironmentalriskshavereceivedrelativelylessattentioninresearchon3
cooperationandcollectiveaction,theoreticalandempiricalstudiesofrisk‐poolinginanthropology4
(25,26)andeconomics(27,28)haveexploredinteractionsbetweenstrategicandenvironmental5
risks.Smith(29)suggestsrisk‐poolingislikelytooccurwhenanindividual’ssuccessinresource6
acquisitionexhibitsstochasticvariationthatisasynchronousamongindividuals,creating7
opportunitiesforindividualstoreduceenvironmentalriskbysharingresources.Relatedeconomic8
studieshaveidentifiedtheuseofnon‐marketmechanisms—includinginformalloans,remittances,9
andsocialnetworks—topoolriskandminimizethenegativeeffectsofconsumptionvariability(16,10
30,31).11
Smoothingconsumptionbypoolingresourcescanenhanceoddsofsurvival,butthisformof12
cooperationentailsstrategicriskinboththeproductionandsharingdomains.Assuch,the13
insuranceprovidedbypoolingresourcespresentsanothersocialdilemmasincefree‐ridersmay14
benefitwithoutcontributing,underminingthelong‐termstabilityofrisk‐pooling.Related15
theoreticalmodelshaveshownastrongcommitmentdeviceisneededtofacilitateeffectiverisk‐16
pooling,insuringthelong‐termbenefitsofparticipationexceedtheshort‐termgainsofleavinga17
network(32).18
Experimentalresearchechoestheresultsofthesemodels.Studieshaveexplored19
commitmentinthecontextofendogenousgroupformation(33,34).Forexample,BarrandGenicot20
(33)foundindividualsweremostlikelytoformrisk‐poolinggroupsinthepresenceofastrong,21
exogenouslyenforced,commitmentdevice.CharnessandGenicot(35)findstrongevidenceforrisk‐22
poolingwithalimitedcommitmentdevice;however,directreciprocityisacentralfeatureoftheir23
6
incentivestructure.Incontrast,directreciprocityisnotanexplicitfeatureofourdesign,which1
allowsustotestforrisksharingintheabsenceofcommitmentdevices.2
Ourstudycomplementsexistingresearchbyintegratinginsightsonrisk‐poolingwithmore3
generaltheoreticalandempiricalresearchoncooperation.Specifically,wecombinefactorsthat4
increaseinterdependenceandencouragerisk‐pooling—stochasticresourceacquisitionand5
voluntaryresourcesharing—withfactorsthatamplifystrategicrisksofdefection—rewardsand6
reputations.Weutilizemethodologicaltoolsfromanthropologyandeconomicstodesignaseriesof7
fieldexperimentsinvolving136participantsfrom3villageslocatedontheKamchatkaPeninsulain8
NortheastSiberia.PeoplelivinginKamchatka’sremotevillagesmustcontinuallycopewith9
strategicandenvironmentalrisks,withlimitedsupportfromformalinstitutions(36).Priortothe10
experiments,weconductedqualitativeethnographicinterviewsandparticipantobservationto11
identifytheparticularstrategicandenvironmentalrisksthatpeopleinKamchatkaface.These12
insightsinformedthedesignofourexperiments.13
ResearchDesign14
OurfieldexperimentswereconductedinthreesmallcommunitiesintheKaraginskiiregionof15
KamchatkaoverafourdayperiodineachcommunityduringSpring2011.Thisisalarge,remote16
region(40,600km2)withasmallpopulation(4,824people)thatisdependentuponharvestinglocal17
resourcesforsubsistence.Approximately85%ofexperimentparticipantswereindigenousandhad18
livedintheareaformostoftheirlives.19
Subjectswererecruitedthroughbulletinboardannouncements,door‐to‐doorvisits,andby20
alocalcommunitycoordinator.ExperimentswereconductedinRussianandallsupporting21
materialswerepresentedinRussian.Participantsreadaconsentformpriortothestartofthe22
experimentandprovidedverbalaffirmationofinformedconsentpriortoparticipation.Signatures23
werenotcollectedsinceourstudywasdeterminedtobeofminimalrisk,subjectsexperiencedrisk24
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similartothatencounteredineverydaylife,andsignatureswouldhaveunnecessarilylinked1
subjectstothestudy.Investigatorcontactinformationwasprovidedtosubjectsandleftwithvillage2
mayorsandcommunitycoordinators.Researchersreturnedtocommunitiestwoyearslaterto3
reportrelatedresearchfindingstoparticipantsandcommunitymembers.Ourstudyandconsent4
procedureswereapprovedbytheUAAInstitutionalReviewBoard(projectid#216266).The5
protocolwaspre‐testedwithnativeRussian‐speakingstudentsattheUniversityofAlaska6
Anchorage.InstructionswerereadaloudandaccompaniedbyPowerPointslidesprojectedontoa7
screen.InstructionsinEnglishandRussian,fieldprotocol,andanimageofinformationdisplayedto8
subjects,canbefoundatthedatareviewurlincludedinoursubmission.9
Eachsessionlastedapproximatelythreehours,duringwhichsubjectsplayedamodified10
versionofalinearpublicgoodsgame.Experimentswerehand‐run,withtheaidofasinglelaptop11
computerandaprojector.Foreachround,decisionswerewrittenonslipsofpaper,collectedby12
oneoftheexperimenters,andenteredintoaspreadsheet.Resultswereprojectedontothescreen,13
andsubjectswrotetheoutcomesonarecordsheet.Oncethisprocesswascompleted,another14
roundfollowed.15
Subjectswererandomlyassignedtooneoftwofive‐persongroups.In4ofthesessions16
therewasone5persongroupandone4persongroup.Intheremaining10sessionstherewere217
fivepersongroups.Inalltreatments,individualswereidentifiedbyaletterknownonlybythe18
individualandtheexperimenter.Thus,althoughparticipantsknewthecompositionofeachgroup,19
therewasnowayforothergroupmemberstolinkanindividualtohisorherdecisions.Moreover,20
withoneexception(describedlater),eachindividual’sletterrandomlyvariedeveryround.This21
methodeliminatedthepossibilityofusinginformationaboutaparticulargroupmember’sactions22
inpriorroundsandpreventedindividualsfromdevelopingreputations.23
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Subjectswerepaidincash,withaverageearningsof610rubles(about$22USdollarsatthe1
time),equivalenttoatypicaldailywage.Inaddition,allparticipantsreceiveda200rubleshow‐up2
payment.3
Themodifiedpublicgoodsgamewasframedasteamsubsistenceproduction(37,38),and4
consistedoftwostages.Stage1wasidenticalforallgroupsandconsistedofastandardlinear5
publicgoodsgameforfiverounds.ThisservesasourBaselineTreatment.Eachround,every6
individualstartedwithaninitialendowmentof50“hours”whichhadtobeallocatedbetweenan7
individualandagroupactivity.Theactivitywasframedas“fishing,hunting,orcollecting8
mushroomsandberries…”where“sometimesyoudotheseactivitiesonyourown”(theindividual9
productionactivity)but“sometimesyoudothemwithotherpeople”(thegroupproduction10
activity).Eachhourallocatedtotheindividualactivityyieldedaprivatereturnof10rubles.Time11
allocatedtothegroupactivityyielded20rublesperhour,because“peopleoftengetmoredone12
whenworkingtogether.”Returnsfromthegroupactivityweredividedequallyamongallgroup13
members,regardlessofthetimeallocated.Attheendofeachround,theallocationdecisionofeach14
groupmemberwaspubliclyrevealed(identifiedonlybyaletter).15
Stage2consistedofeightadditionalroundsunderoneoffoursharingtreatments.16
Treatmentsvariedintermsofthepresenceofenvironmentalriskandincentivestocooperateas17
determinedbytheinformationavailabletosubjectswhenmakingdecisions.Inalltreatments,18
subjectsfirstmadethesametimeallocationdecisionasinStage1.Afterthedecisionsweremade,19
someinformationwasrevealed,thensubjectsweregiventheopportunitytosharerubleswith20
othergroupmembers.Theinstructionsemphasizedthevoluntarynatureofsharingandusedthe21
Russianverbpodelit’sya(“toshare”).Therewasnorestrictiononthenumberoffellowgroup22
memberswithwhomanindividualcouldshare.Toavoidsharingcommitmentsinexcessofan23
individual’searnings,thetotalamountsharedbyanindividualwaslimitedto250rubles.Table1.24
summarizeskeyinformationforeachtreatment.25
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Table1.ExperimentalDesign1
RiskandSharingTreatment InformationRevealedPriortoSharingDecision
Treatment NIdiosyncratic
RiskVoluntarySharing
PlayerShocked
Allocationdecisionsincurrentround
Alldecisionsinpriorrounds
Baseline 136 no no ‐‐ ‐‐ ‐‐
Reward 40 no yes ‐‐ yes no
Shock 29 yes yes yes no no
NoReputation 38 yes yes yes yes no
WithReputation 29 yes yes yes yes yes
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RewardTreatment.ThefirsttreatmentwasidenticaltotheBaselineexceptthataftertime3
allocationdecisionswerecompletedandpubliclyrevealed,subjectsmadeasharingdecision.4
Becauseindividualtimeallocationdecisionswerecommonknowledge,subjectscouldusesharing5
asamechanismtorewardothersforcontributingtothegroupactivityinthecurrentperiodorto6
indirectlypunishnon‐cooperatorsbywithholdingsharing,increasingthecostofdefectionrelative7
totheBaselineTreatment.Becausesharingwasazero‐sumtransfer,ithadnoimpactongroup8
earnings.Aftersharingdecisionswerecollected,theamountssharedandreceivedwererevealedto9
thegroup.NotethatinallStage2treatments,onlyaggregatesharingoutcomeswererevealed;the10
amounttransferredbetweentwoparticularplayerswasnotdisclosed.Thistreatmentissimilarto11
theRewardTreatmentinSefton,ShuppandWalker(39).12
RiskTreatment.Thesecondtreatmentintroducedidiosyncraticenvironmentalrisk.Afterthetime13
allocationdecisionsweremade,butbeforetheywererevealed,oneindividualfromeachgroupwas14
randomlyselectedbytherollofadietoincura“shock”whichwasdescribedas“notcatchingany15
fish,gettingsick,orhavingallthefoodyou’vegatheredspoil.”Theindividualwhoincurredthe16
shocklostallearningsfromboththegroupandindividualactivities.Onlytheamountreceivedfrom17
voluntarysharingbyothersdeterminedtheindividual’searningsforthatround.Theletterofthe18
individualincurringtheshockwasannouncedtothegrouppriortothesharingdecision.Afterthe19
10
sharingdecisionswerecollected,boththetimeallocationandsharingdecisionsofallgroup1
memberswererevealed.2
Risk/RewardTreatment.ThethirdtreatmentwasidenticaltotheRiskTreatment,exceptthat3
priortothesharingdecision,boththeletteroftheindividualshockedandtheallocationdecisions4
ofallgroupmemberswererevealed.Thisallowedsharingtobebasedonwhetheranindividual5
wasshockedand/ortheindividual’stimeallocationinthecurrentperiod.Afterthesharing6
decisionswerecollected,theindividualsharingandtimeallocationdecisionswererevealedtothe7
group.8
Risk/Reward/ReputationTreatment.Inthefinaltreatment(whichwewillrefertoasthe9
ReputationTreatment),individualplayerletterswereconstantacrossrounds,butotherwise10
followedthesamerulesastheRisk/RewardTreatment.Holdingplayerlettersconstantcreatedan11
opportunityforindividualstodevelopareputationforcooperativebehaviornotonlyinthe12
productiondomain,butalsothesharingdomain.Thisallowedothergroupmemberstocondition13
sharingonthesereputations.TheReputationTreatmentbringstheexperimentclosertonaturally14
occurringcontextsofcooperationinsmall‐scalesocieties,whereindividualshaveaccesstoand15
utilizereputations.16
Individualcashearningsweredeterminedbyasingleroundthatwasrandomlyselectedby17
adierollattheendoftheexperiment(13,35).Selectingasingleroundeliminatedthepossibility18
forsubjectstopoolearningsovertime,whichwouldhavebeenanalogoustoindividuallyinsuring19
againstshocks.OurdesignchoiceparallelsfieldconditionsinnorthernKamchatkawherethereis20
substantialseasonalvariationinweatherandresourceavailabilityanditisdifficulttoself‐insure21
againstshockstosubsistenceharvests.22
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RelatedStudiesandHypotheses1
ThedesignofourexperimentismostsimilartoacomputerizedlaboratoryexperimentbyCherry,2
Howe,andMurphy(13)butdiffersintermsoftheframing,thesourceoftheshock,thenatureof3
sharing,andtheamountofinformationrevealed.Theyfindstrongevidenceforrisk‐pooling4
withoutacommitmentdevice.Incontrast,ourdesignintroducesunavoidableidiosyncraticriskand5
allowsustotesttheeffectofreputationsonsharingandcooperationdecisions.6
Ineachofourtreatments,thestaticNashequilibriumallocationstothegroupactivityand7
tosharingarebothzero.Further,becausedirectreciprocitywasnotpossibleinourgame8
environmentgivenactualdecisions,sharingarrangementsarenotself‐enforcing;thatis,the9
expectedfutureindividualgainfromcooperatingbysharingdoesnotexceedthecurrentbenefitof10
defecting.EssentialfeaturesofthisdecisionenvironmenthavebeenmodeledbyNowakand11
Sigmund(9)whoexplorecooperationviaindirectreciprocity.Inourdecisionenvironment,indirect12
reciprocityisdefinedasthesharinggiventoanindividualthatisconditionedontheobserved13
cooperationofthatindividualwithothergroupmembersinboththeproductionandsharing14
domainswhenpossible(9,40).15
Agrowingnumberofexperimentalstudiesprovidesupportfortheimportanceof16
reputationandtheroleofindirectreciprocityincooperationandcollectiveaction(4,9,40–42).In17
thecontextoftwolinkedcooperativedomains,Panchanathan&Boyd(43)suggestindirect18
reciprocitydependsontwoconditions:1)reputationsformedbyactionsinthefirstdomain19
increasebenefitsreceivedintheseconddomainand2)thebenefitsofagoodreputationinthe20
seconddomainexceedthecostsofcooperationinthefirstdomain.Weinvestigatehow21
environmentalriskaffectsthesestrategicdynamicsofreputationandindirectreciprocity.22
BycomparingdecisionsacrossthefourtreatmentsinStage2,wecantesttheextentto23
whichtimeallocationandsharingdecisionsareinterlinkedandhowtheyrespondtorisk.Basedon24
12
thePanchanathan&Boyd(43)modelofindirectreciprocity,wehypothesizethatsharingdecisions1
willbeconditionedonobservablebehavior,andpeoplewhoexhibitmorecooperationinthese2
domainswillreceivemoresupport.Thisimpliesthat intheRewardTreatment,subjectswilluse3
sharingtorewardcooperationandwillpunishnon‐cooperatorsbywithholdingsharing(H1).In4
theRiskTreatment,thoseexperiencingahardshipwillreceiveadditionalsupport,butitwillbe5
independentofallocationandsharingdecisionsbecausetheseareunobservable(H2).Inthe6
Risk/RewardTreatment,sharingwillbedirectedtowardstheindividualwhowasshockedand7
sharingwillincreasewiththeshockedindividual’sgroupallocationdecisioninthecurrentround8
(H3).IntheReputationTreatment,theamountsharedwithashockedindividualshouldincrease9
withbothhisorherallocationdecisioninthecurrentperiodandhisorhersharingdecisioninthe10
previousperiod(H4).Finally,ifweobservesharingthatisconditionedonallocationstothegroup11
activityinthefinaltwotreatments,thenweexpecttheamountoftimeallocatedtothegroup12
activitywillbegreaterthanintheRisktreatment,whichdoesnotfacilitateconditionalsharing13
(H5).14
Results15
Sharing.IntheRewardTreatment,theaverageamountreceivedfromsharingwas96rubles.Inthe16
threetreatmentswithidiosyncraticrisk,theaverageamountreceivedwasnotsubstantially17
different;however,sharingwasoverwhelminglydirectedtowardthoseexperiencingahardship.18
Moreover,themoreashockedindividualcooperatedintheproductiondomain,themoreheorshe19
receivedfromsharing.WeexplorethisresultwithfourrandomeffectsregressionmodelsinTable20
2,oneregressionforeachofthefourStage2treatments.Themodelsallusethesamebasic21
structure:Yit = 0 + 1it + 2t + i + it,whereinTable2.Yitisthetotalamountreceivedin22
sharingbysubjectiinroundt[6,13],itisasetofindependentvariablesthatcontrolforwhether23
eachindividualwasshocked,theamountsharedinthepreviousperiod,theamountallocatedtothe24
13
groupactivityinthecurrentperiod,andinteractionsofthesevariables,icapturesunobserved1
individualsubjectcharacteristicsanditrepresentsthecontemporaneouserrorterm.Because2
subjectsparticipatedinmultipleroundsofasingletreatment,subject‐specificheterogeneityis3
modeledasarandomeffect.WeuseaHuber(44)andWhite(45)robustestimateofvariance.4
Table2.IndividualAmountReceivedfromSharing(Stage2)5
Reward Risk Risk/Reward ReputationAmountSharedt–1 0.09(0.06) 0.14(0.12) 0.07(0.06) 0.03(0.07)GroupActivityt 1.15***(0.39) ‐0.31(0.25) ‐0.25(0.36) ‐0.22(0.52)Shockedt 108.24*** (24.53) 82.18** (32.99) ‐40.70(42.69)ShockedtXAmountSharedt–1 ‐0.14(0.19) ‐0.19(0.13) 1.16**(0.55)ShockedtXGroupActivityt 2.48(1.51) 2.28** (1.14) 5.66***(1.73)Periodt ‐0.92(1.43) ‐1.18(1.76) ‐2.78** (1.16) ‐2.30(1.87)Constant 72.71***(22.64) 45.60** (22.27) 72.87*** (16.62) 73.13**(33.38)N 280 161 210 161Robuststandarderrorsinparenthesesareclusteredatthegroup‐level.Dependentvariableisthe6
amountreceivedinsharing.Statisticalsignificance:***:p<0.01;**:p<0.057
ThefirstmodelshowsresultsfortheRewardTreatment,whichdoesnotincludeashock8
andthereforerelatedvariablesarenotincluded.ConsistentwithH1,theGroup_Activitytcoefficient9
ispositiveandstatisticallysignificant.Conversely,whethertheindividualsharedresourcesinthe10
previousroundisunknownand,asexpected,theAmount_Sharedt–1variableisnotsignificant.Thus,11
consistentwithSefton,Shupp,andWalker(39),individualsusedthesharingmechanismtoreward12
cooperativebehaviorinthegroupactivitydecision.However,themagnitudeoftheeffectis13
relativelymodest.Eachhourallocatedtothegroupactivityyieldedareturnof5.15rubles—1.1514
receivedfromsharingplus4rublesfromthegroupactivity—whichisonlyabouthalfofthe1015
rublereturnfromanhourallocatedtotheindividualactivity.Recallthateveryhourallocatedtothe16
groupactivityyields4rublesfortheindividual,aswellaseachoftheothergroupmembers(2017
rublesperhourwhichisevenlydividedamongallfivegroupmembers).18
Thenextthreemodelsincludeinteractionsofwhethertheindividualwasshocked,the19
allocationtothegroupactivityinthecurrentround,andtheamountsharedinthepreviousround.20
14
Inalltreatments,individualsconditionedsharingdecisionsontheavailableinformation,and1
unavailableinformationisnotsignificant,asexpected.IntheRiskTreatment,participantsreceived2
anaverageof108.24rublesjustforincurringashock,supportingthehypothesis(H2)thatpeople3
usesharingtoassistthoseinneed.Withmoreinformationaboutothergroupmembers’behaviorin4
theRisk/RewardandReputationTreatments,sharingwasstilldirectedtowardthoseinneed,and5
theamountreceivedincreasedforthoseindividualswithhigherlevelsofcooperationinthegroup6
activity(Figure1.).IntheRisk/Rewardtreatment,thosewhoexperiencedashockcontinuedto7
receivesomesupportthatwasindependentoftheiractions(82.18rubles),butsubjectsreceivinga8
shockalsoreceivedanadditional2.28rublesperhourallocatedtothegroupactivity(consistent9
withH3).IntheReputationtreatment,behaviorinboththecurrentandpreviousroundswas10
commonknowledge.InsupportofH4,sharingwasconditionedonboththeshockedindividual’s11
mostrecentsharingdecision(periodt–1)andthemostrecentgroupactivitydecision(periodt).12
Foreachrubleshared,shockedplayersreceived1.16rublesinsharing.Foreachhourallocatedto13
thegroupactivity,shockedplayersreceived5.66rublesinsharing.InboththeRisk/Rewardand14
ReputationTreatments,sharingwasnotusedtorewardcooperationindependentoftheshock.15
Instead,sharingwasdirectedonlytowardthoseinneedandwasconditionedontheircooperation. 16
15
1
Figure1.Predictedindividualamountreceivedinsharing,conditionedonwhetherthe2 individualreceivedashock,usingcoefficientsinTable2.3
GroupActivity.Inthefirstfiverounds(Stage1),allgroupsparticipatedintheBaselineTreatment.4
InStage1,averageallocationstothegroupactivity(about40%oftheinitialendowment)were5
consistentwithresultsfromotherlinearpublicgoodsgames(2,46).Table3presentstheresultsof6
tworandomeffectsmodelsforthegroupactivitydecisioninStage2(rounds6‐13only).Inthese7
regressionsthedependentvariableYitistheindividualallocationtothegroupactivityofsubjectiin8
roundt.Model2addsindividualcharacteristicsandfixedeffectsforthecommunities.Toprotect9
subjectconfidentialityandtomakedatapublicallyavailableforreplicationwehavenotidentified10
specificcommunities,gender,orraceintheregressionresults.Weexploitthewithin‐subjectdesign11
byusingtheindividual’saveragegroupallocationoverallfiveroundsofStage1Baselineasan12
independentvariable(BaselineGroupActivity).Sincetheidiosyncraticenvironmentalriskwas13
unavoidable,cooperationintheRiskTreatmentshouldbeunaffectedbyrisk,whichisprecisely14
whattheresultsinTable3suggest.However,contrarytoH5,theabilitytosharefailedtoincrease15
01
002
003
004
005
00A
mo
unt r
ece
ive
d fr
om s
harin
g
0 10 20 30 40 50Allocation to the group activity
Risk/Reward (Not Shocked) Reputation (Not Shocked)Risk/Reward (Shocked) Reputation (Shocked)
16
cooperationinboththeRisk/RewardandReputationtreatments.Althoughresultsindicatesharing1
withthoseexperiencingtheshockisconditionedontheindividual’sallocationtothegroupactivity2
(Table2),thelevelsofsharingareinsufficienttoinduceanincreaseincooperation.Ifaperson3
receivesashockintheReputationTreatment,thereturnfromanhourallocatedtothegroup4
activitywas9.66rubles(5.66asrewardforanallocationviasharingplus4fromthegroup5
activity),whichisstilllowerthantheperhourreturnof10rublesfromtheindividualactivity.6
7
8
17
Table3.IndividualAllocationtoGroupActivity(Stage2only,rounds6‐13)1
Model1 Model2
RewardTreatment omitted omitted
RiskTreatment ‐1.642(1.76) ‐1.849(1.60)
Risk/RewardTreatment ‐0.961(1.74) ‐0.947(1.77)
ReputationTreatment 0.380(2.86) 0.642(2.54)
Round ‐0.095(0.16) ‐0.095(0.16)
BaselineGroupActivity 0.775***(0.10) 0.754***(0.11)
Gender1 ‐1.525(1.52)
Age 0.099**(0.04)
Race1 ‐0.206(2.07)
Community1 ‐3.427**(1.42)
Community2 ‐1.595(1.73)
Community3 omitted
Constant 3.616(2.70) 2.375(2.93)
N 1088 1072
Robuststandarderrorsareclusteredatthegroup‐level.BaselineGroupActivityisthemeanofthe2
individual’sdecisionsintheStage1Baselinetreatment(rounds1‐5).Dependentvariableisthe3
individualallocationtothegroupactivity.Statisticalsignificance:***:p<0.01;**:p<0.054
Thus,wefindsomesupportforPanchanathan&Boyd’s(43)modelofindirectreciprocity.5
Individualsinneeddoreceivesubstantialsupport,and,whenpossible,thissupportisconditioned6
ontheirreputationsforcooperation.However,thebenefitsfromapositivereputationdidnot7
exceedthecostsofparticipatinginthegroupactivity,andasaresult,theabilitytosharedidnot8
increasecooperation.9
18
Discussion1
Wesystematicallyexaminedtheinteractionsofstrategicandenvironmentalrisksamongpeoplein2
Kamchatkawhofacethesechallengesrepeatedlyinthepost‐Sovietera(47).Introducing3
idiosyncraticenvironmentalriskinthesocialdilemmaincreasedinterdependence,andpeople4
respondedbychannelingresourcestothoseinneed,rewardingindividualsforcooperation,and5
punishingindividualswhodidnotcooperate.Theabilitytoshareasatooltomitigate6
environmentalriskincreasedtheinterdependenceamonggroupmembers.Asaresult,highlevels7
ofsharingwereachievedwithoutdirectreciprocityorastrongcommitmentdevice.Observed8
sharingis,however,consistentwithlocalsharingnorms.Wefindstrongevidenceforsharing,even9
withoutreputations,whichisconsistentwithamodelofpro‐socialbehavior(andrelated10
experimentalresults)inwhichpreferencesforkeepingsocialrulesarethedrivingforcebehind11
pro‐socialbehavior(48).12
Whencurrentorpastbehaviorwasobservable,sharingwasconditionedonobserved13
cooperativebehavior.IntheRewardTreatment,individualswhoparticipatedmoreinthegroup14
activityreceivedmorefromsharing,consistentwithpreviousstudiesthatemphasizethe15
importanceofrewards,punishments,andreputationsfortheemergenceofcooperation(42,49).16
Thepositiverelationshipidentifiedbetweensharingandallocationstothepublicgoodinthe17
Risk/RewardandReputationTreatmentssuggeststhatwhenbothstrategicandenvironmental18
risksarepresentinasocialdilemma,theeffectsofstrategicrisksdependonenvironmentalrisks.19
Theseresultshaveimportantimplicationsforresearchonrisk‐pooling,theroleofreputations,20
rewards,andpunishmentsintheoriesofcooperation,andmoregenerally,theroleof21
environmentalvariabilityinhumanadaptationandresilience.22
Ethnographicresearchonrisk‐poolingemphasizestheimportanceofsupportingthosein23
needandmechanismsofreputationtomaintaincooperation(25,50).Labexperimentsinspiredby24
19
thisresearchhavedemonstratedthathigh‐varianceresourcesandreputationscanplayakeyrole1
intheemergenceofrisk‐pooling,dramaticallyincreasingreciprocalexchangesamongindividuals2
relativetolow‐varianceresources(51)andthatrisk‐poolingstrategiescanincreaseindividualand3
pair‐wisesurvivalinenvironmentswithhighdegreesofrisk(52).Similarly,agent‐based4
simulationshaveshownincreasedenvironmentalharshness—whichcanbemitigatedvia5
cooperation—canamplifycooperation(53).Eachofthesestudiesemphasizestheimpactof6
interdependenceontheemergenceofcooperation.Wecontributetothisworkbydemonstrating7
howasymmetriesofneedcausedbystochasticenvironmentalrisksor“shocks”interactwiththe8
strategicriskstiedtorewards,punishments,andreputationstoincreaseinterdependenceand9
enhancerisk‐pooling.InboththeRisk/RewardandReputationTreatments,individualswho10
contributemoretothepublicgoodreceivemoreviasharing,butonlywhentheysufferashock.11
Theseinteractionsbetweenstrategicandenvironmentalriskssuggeststrategicrisksremain12
importantforpreciselythoseindividualswhobenefitmostfromrisk‐pooling,discouraging13
defectorsandfree‐riders.Indeed,wefoundtheeffectivenessofrisk‐poolingincreasedwhenpeople14
hadtheabilitytomonitorandactuponreputationsacrossmultiplerounds.Whileprevious15
researchhasemphasizedtheimportanceofexogenouscommitmentdevices,formalinstitutions,16
endogenousgroup‐formation,anddirectreciprocityforeffectiverisk‐pooling,ourexperiments17
showthatrisk‐poolingcanemergefromendogenousreputationdynamicsandindirectreciprocity.18
Althoughtheinteractionofstrategicandenvironmentalriskenhancedtheeffectivenessof19
risk‐pooling,wedidnotobservesystematicincreasesinthegroupactivityreportedbyprevious20
studieswhererewardsareofferedinthecontextofasocialdilemma(5,39,42).Oneexplanationis21
thatthebenefitsofgoodreputationsforcooperatorsneverexceedthecostsofcontributingtothe22
publicgood.Previousstudieswithasimilartwo‐dilemmadesignamplifytheimpactofreputations23
byincreasingtherelativecostsandbenefits(i.e.efficiency)ofrewardsand/orpunishments,often24
withratiosashighas1:3(4–7,54).Thus,increasinglevelsofcooperationobservedinprevious25
20
experimentsmaynotbeduetothepresenceorabsenceofrewardsandpunishmentsperse,butthe1
presenceofhighlyefficientrewardsandpunishments(55–57).Whilehighlyefficient2
reward/punishmentmechanismshavebeenshowntoincreaselevelsofcooperationin3
experiments,itislessclearhowoftensuchmechanismsareavailableinnaturallyoccurring4
contextsofcooperation(58).Indeed,thewayparticipantsconditionaidtoneedyplayersbasedon5
cooperationreflectslocalnormsofindirectpunishment,whicharemorecommonlyobservedinour6
studyregionthannormsofdirect,individualcostlypunishment.7
Inadditiontoaddressingindividualstrategicbehavior,ourstudyhighlightstheimportant8
roleoffactorsthatincreaseinterdependenceamongindividuals.Weinvestigatedonefactor—9
stochasticresourceacquisition—thatincreasesinterdependencebycreatingconsumptiondeficits10
thatcanbeovercomebypoolingresourcesthroughsharing.Suchdeficitsmightalsoarisefrom11
differencesinindividual/householdproductivecapacityandconsumptiveneeds(59)orstochastic12
differencesinharvestsduetopoorhealthorothermisfortunes(60,61).Ourexperiments13
incorporateconsumptiondeficitsviastochasticshocks,providingaspecificfactorforamplifying14
theimpactofreputationsrelativetothehighlyefficientrewardandpunishmentmechanisms15
utilizedinpreviousstudies.16
Scholarsstudyingprocessesofcontemporaryhumanadaptationtounprecedentedforcesof17
globalclimatic,economic,political,andculturalchangehaveemphasizedthecrucialroleof18
strategiesthatmitigateenvironmentalrisks(62).Manycomponentsofcontemporaryadaptation—19
includingtheroleoftraditionalecologicalknowledge,socialnetworks,institutions,andotherforms20
ofsocialcapital—dependoncooperationamongindividualstomaintainresilienceinthefaceof21
shocksandperturbations(63).Therefore,understandinghowenvironmentalrisksinteractwith22
strategicriskstoaffecttheemergenceandstabilityofcooperationcanimproveourattemptsto23
adapttothechallengeswefaceincontemporaryenvironments.Ourresearchsuggeststheoriesof24
21
cooperationcancontributetothisgoalbyinvestigatingabroaderrangeoffactorsthatincrease1
interdependence.2
Acknowledgements3
ThisresearchwassupportedbytheNationalScienceFoundation(#0729063and#1019303).DG4
wassupportedbyapost‐doctoralfellowshipfromtheNationalSocio‐EnvironmentalSynthesis5
Center(SESYNC)underfundingfromtheNationalScienceFoundation(DBI‐1052875).Wewishto6
thankallthepeopleinKamchatkawhoparticipatedinourresearch,aswellasDr.Viktoria7
Petrasheva,TatianaDegai,andDanielAllenforresearchassistance.WeespeciallythankCristina8
GainaBlantonwhoassistedintranslations,transcriptions,andconductingfieldexperiments.We9
thankMarthaMadsenatExploreKamchatkaforoutstandinglogisticssupport. 10
22
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