Table Of ContentARTICLEADDENDUM
Communicative&IntegrativeBiology5:2,209–213;March/April2012;G2012LandesBioscience
Could shame and honor save cooperation?
Jennifer Jacquet,1,2,* Christoph Hauert,1 Arne Traulsen3 and Manfred Milinski4
1DepartmentofMathematics;UniversityofBritishColumbia;Vancouver,BCCanada;2SeaAroundUsProject;UniversityofBritishColumbia;Vancouver,BCCanada;
3ResearchGroupforEvolutionaryTheory;Max-Planck-InstituteforEvolutionaryBiology;Plön,Germany;4DepartmentofEvolutionaryEcology;
Max-Planck-InstituteforEvolutionaryBiology;Plön,Germany
Shameandhonoraremechanismsthat common pool. However, a group of non-
expose behavior that falls outside contributors does not increase their initial
the social norm. With recent six-player capital, whereas a group of cooperators
public goods experiments, we demon- doubles their income. This generates a
strated that the threat of shame or the social dilemma characterized by the con-
promiseofhonorledtoincreasedcoopera- flictofinterestbetweentheindividualand
tion.Participantsweretoldinadvancethat the group.3.4 This conflict of interest was
aftertenroundstwoparticipantswouldbe beautifully illustrated by one student in
asked to come forward and write their a questionnaire handed out at the end of
names onthe board infrontof the fellow the experiments (Fig.1).
© 2012 Landes Bioscience.
group members. In the shame treatment, In the shame treatment, we exposed, as
the least cooperative players were exposed we had announced at the start, the two
andwrotetheirnamesunderthesentence participants who were least generous after
D“I odo nnateod tlea sdt”iwshitlerithbe uhotnoered. the tenth round and, in the honor treat-
participants wrote their name under ment, the two most generous players were
“I donated most.” In boththe shame and revealed. These two players were asked to
honortreatments,participantscontributed come to the front and write their real
approximately 50% more to the public name on a board visible for all under the
good, as compared with the control treat- sentence “I donated least” (shame) or “I
ment in which all players retained their donated most” (honor). The other four
anonymity. Here, we also discuss how players remained anonymous in both
shame and honor differ from full trans- groups. Contributions to the public good
parency, and some of the challenges to were approximately 50% higher as com-
understanding how anonymity and expo- pared with the control, where all six
suremodifybehavior. players knew that they would remain
anonymous over all 12 rounds (Fig.2).
This demonstrates that both shame and
Can shame and honor lead to greater honor can drive cooperation.
Keywords: cooperation, honor, cooperation? We recently tested this ‘Shame’ and ‘honor’ are polysemous
public goods game, shame, question with apublic goods game, atype suchthattheycanbeusedasnounsaswell
tragedy of the commons of experiment often used to study the as verbs. In our experiments, we did not
conflict between group and self-interest.1,2 examine whether the participants felt the
Submitted: 12/09/11
Over 12 rounds, six participants recruited emotions shame or honor when their
Accepted: 12/12/11 fromthesameclasscouldchoosetoinvest identity was revealed to the group, but
http://dx.doi.org/10.4161/cib.19016 a certain amount of their allotted capital, rather whether they would respond differ-
endowed tothematthestart ofthegame, ently to a cooperative experiment when
*Correspondenceto:JenniferJacquet;
Email:[email protected] into a common pool or keep it. The there was a threat or an opportunity of
total investments in the common pool being singled out in response to their
Addendumto:JacquetJ,HauertC,TraulsenA, were then doubled and equally divided actions. We employed shame and honor
MilinskiM.Shameandhonourdrivecooperation. among all participants. Thus, in each as verbs, in that we exposed individuals
BiolLett2011;7:899–901;PMID:21632623;http:// game non-contributors are better off that made aberrant choices—in one case
dx.doi.org/10.1098/rsbl.2011.0367
than cooperators that contributed to the uncooperativerelativetothegroupaverage
www.landesbioscience.com Communicative&IntegrativeBiology 209
and, in the other case, highly cooperative
relative to the group average.
When it comes to shame and honor,
the reference scale is provided by the
currently accepted social norms. For
example, the fear of being shamed for
not adhering to standards for personal
hygiene might encourage adherence to a
social norm without the fear of physical
punishment, fines, or incarceration.
Shame and honor can be considered sub-
classifications of punishment and reward.
Whitman5 sorts punishments into five
sorts of deprivations: life (execution);
liberty (imprisonment); bodily safety
(corporal violence); property (fines); and
what he calls “dignity” (shaming). We
would also consider two more potential
deprivations: access to the group (ostra-
cism) and manipulation of social status
(gossip). Shaming, ostracism and gossip
are often non-regulatory in the sense that
members of the public can legally exert
these punishments, while the law often
© 2012 Landes Bioscience.
consigns the use of execution, imprison-
ment, corporal violence and fines as
exclusive punishments of the state.
Do not distribute.
From an evolutionary perspective the
emergence of any kind of punishment
Figure1.Feedbackofadisillusionedstudentintheanonymouscontroltreatment.Thesix behavior that is costly to the punisher
participantsweredeliberatlyrecruitedfromthesameclassandearlyduringthetermsoeveryone
remainsunclear.Aslongassuchpunishers
knewthattheywouldencounteroneanotheragain.
are rare, they have to punish frequently
andwidelyinordertoenforce compliance
and hence will perform poorly. Neverthe-
less, punishment is ubiquitous in human
andanimalsocieties.6Interestingly,theore-
tical and experimental work suggests
that voluntary participation in social
enterprises—which corresponds to the
positive complement of ostracism—could
be key, following Hardin’s2 principle of
‘mutual coercion mutually agreed upon’.
This principle has been demonstrated in
recenttheoreticalwork,wherepunishment
behavior and sanctioning institutions can
evolveifindividualsvoluntarilycommitto
such a social norm7,8 and in experiments,
where participants prefer—after an initial
aversion and some adjustment time—
public goods interactions that allow
punishment of other participants.9,10
Figure2.Averageplayercontributions(andstandarddeviation)overthefirsttenrounds
bytreatmentandplayertype(remaininganonymousorexposedafterround10;ithadbeenmade Shaming and ostracism are two economic
clearatthestartthatthiswouldhappen);maximumpossiblecontributionwas$10.Inthecontrol, ways to inflict potentially severe and
allplayerswereanonymous,whileinshameandhonor,fourplayersremainedanonymousand harmful sanctions on individuals.
twoplayerswereexposedafterround10.Groupcontributionsoverthefirsttenroundswere
Amongpairs, cooperation can bemain-
significantlyhigherinthehonorandshametreatments,ascomparedwiththecontrol.
tained in repeated interactions through
210 Communicative&IntegrativeBiology Volume5Issue2
direct reciprocity11 but this becomes exposed only the one player who gave $9. anonymity, and higher contributions to
challenging in larger groups and fails if Moreover, in this case, we questioned the public good with lower levels of
interaction partners change. Here, repu- whether the reference point of the group’s anonymity. In comparison, our experi-
tation and gossip play a decisive role in average to determine what was ‘shameful’ ments exposed only two out of six players
establishing and maintaining coopera- was useful—shame and honor are prob- andachievedasimilarincreaseincoopera-
tion.12 In particular, cooperation thrives ably most efficient when there is wide tion. Groups threatened with shame and
if individuals gain reputation through variance in behavior. enticed with honor donated 53% and
cooperative actions and target their co- At least three previous experiments 48% more, respectively, than groups who
operative efforts toward others that have a tested the outcome of transparency on could rely on retaining their anonymity.
highreputation.Tolearnthereputationof cooperationbyrevealingtheidentityofall While the players ‘honored’ after round
potential interaction partners, the spread participants with variable degrees of expo- 10 gave significantly more than their
of information or gossip becomes essen- sure. In a one-round public goods game, co-players that remained anonymous (2
tial.13 Similarly, gossip about whether an every player had to reveal his or her con- samplet-test,n =20,n =40,
h(exposed) h(anon)
individual punishes non-contributors is tribution in front of the ten-person group t = 5.91, p , 0.0001; the player is the
predicted to help to enforce social norms and contributions increased from 34.4% statistical unit; all statistical tests are 2-
and to stabilize cooperation.14 The effi- of possible donations in the anonymous tailed; Fig.2), and the later ‘shamed’
cient interplay between reputation and conditionto68.2%,16oracalculated98% players gave significantly less (2 sample
punishment to promote cooperation has increase. In another eight-round game, t-test, n = 19, n = 41, t =
s(exposed) s(anon)
been demonstrated in an experimental players could see only digital photographs -4.03, p , 0.0017; Fig.2), the overall
setup.10 ofallfivegroupmembersalongwiththeir differences over the course of the first 10
In real world settings, non-regulatory donationsateachroundandcontributions rounds cannot be accounted for by the
mechanisms are often of interest because increased from 30.3% of possible dona- increased contributions of those partici-
state regulations can be difficult to instate tions in an anonymous treatment to pants that lost their anonymity and hence
and costly to enforce. Transparency 48.1%,17 or a calculated 60%. In a third suggeststhatthepatterns observedarenot
© 2012 Landes Bioscience.
policies,whichrevealthebehaviorofevery design, the group of four players could necessarily driven by the effects of pub-
entity involved, are gaining popularity.15 talk before and after the experiments but licity on low- or high-contributing parti-
Theseincludeinitiativessuchasthepublic were anonymous to each other until the cipants. Instead, all players cooperated
healthpolicies inLosAngeles County and Dtenoth anndofintal rdouinds, twrheinballupltayeers.’ more.
New York City where all restaurants must identities were revealed; group contribu- For instance, the players who remained
display a grade card (A, B, or C) that tions increased from 50.5% of total anonymous in the shame treatment gave
signalstherestaurant’smostrecentgovern- possible contributions under anonymous more over 10 rounds than the top four
ment hygiene inspection (restaurants that conditionsto70.5%,18whichtranslatesto most generous players in each group
fall below the ‘C’ score are closed). a 40% increase. of the control treatment (2 sample t-test,
Transparency requires that consumers These studies reveal a trend of lower n = 41, n = 40, t = 2.92,
s(anon) c(top4)
of the information assess its reliability and contributions with higher levels of p = 0.0046). Overall, the distributions of
set the thresholds for acceptable per-
formance themselves, which can be quite
anoneroustaskintimesofaninformation
overload. In contrast, policies that aim to
shame or honor expose only a section of
the population, such as the delinquent
tax websites in many US states, and the
threshold for acceptable behavior is often
implicit. However, with shame and honor
it can still be difficult to determine at
which point behavior becomes aberrant.
Fortaxpayersinarrears,forinstance,some
US states publish the names of only the
top 250 delinquent taxpayers or those
owing more than a certain amount (e.g.,
$100,000). In our own experiment, one
group in the shame treatment was highly
cooperative: five players fully cooperated
and gave $10 over 10 rounds and one
player gave $9. In this case, we tweaked
Figure3.Histogramofthedonationsoverfirsttenroundsoftheexperiment.
the game, and at the end of 10 rounds
www.landesbioscience.com Communicative&IntegrativeBiology 211
the numbers of players giving higher
amounts shifted with the threat of
shame or honor (Fig.3). However, to
clearly identify differences between the
effects of transparency, anonymity,
shame and honor further experimental
work is required. For instance, would
cooperation also increase if groups were
told two random players of the six
would be exposed with their contribution
rank? This set-up would demonstrate
whether (and to what degree) cooperation
increases due to the threat of mere
exposure, as opposed to the threat of
exposure for extreme behavior, as in our
experiment.
Evidence from our experiment suggests
that certain participants were responding
Figure4.Averageplayercontributionsforrounds11and12bytreatmentandplayertype
to the specific threat of shame or the pro-
(remainedanonymousorexposedafterround10);maximumpossiblecontributionwas$2.
mise of honor. All subjects in our experi-
Inthecontrol,allplayersremainedanonymous,whileinshameandhonor,fourplayersremained
ment also received a one-question survey anonymousandtwoplayerswereexposedafterround10.
following the experiment that asked:
“What was your strategy when you
decided to give or not in each round?” startedpayingattentiontotheindivi- related to the long-term consequences of
The answers also show that som©e pa rt2ici-012du aLlcaonntribdutioenssto mBakieosurseIcwaisenshacmee a.nd honor. We ran two additional
pants made decisions arbitrarily. Responses not in the bottom 2.” roundsafterexposure(Fig.4)andsawthat
included: N “Give only in even rounds, plus the anonymous players in both the shame
N “Eventually I just wanted to be DNol“uI fcnkIyopnuutlmle bdderou7it.s”atcroinibanud itt ewa.s and honor treatments gave nearly equal
amounts, while players who were honored
known as the top contributor.” heads I donated. If it was tails, I
N “Mystrategywastodonateaslittleas wouldn’t donate.” contributed more in the final two rounds
(and significantly more in the 12th round)
possible without being exposed as
someone who contributed least.” Questions remain about the potency of than those who were shamed, suggesting
N “I did not want to be one of the ‘the shameandhonor.Weexposedone-thirdof that those who earned an honorable
least generous players’, so my only thegroup.Asshameandhonorarediluted reputationfeltobligedtomaintainit.
aim was to stay out of the bottom 2, (i.e.,agreaterproportionofthepopulation
other than that I tried to maximize exposed, which gets closer to full trans- Acknowledgments
profit.” parency)ormademoreacute(i.e.,asmaller Thisworkwasmadepossiblewiththehelp
N “Towards the 5th-6th rounds, my proportion), does this change their effec- of the students of University of British
trend of thought changed, and I tiveness? Many questions also remain Columbia and the funding of NSERC.
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