kharealumnicaltechedu article nytimescom sent kharealumnicaltechedu axelrod eh ecoli social psychology nice see old friend still going strong prisoners dilemma old enough qualify aarp membership regarding experimental design interesting 1 used allfemale panel 2 included mix ages 2060 3 used humans confederates computers well imitations last two paragraphs rare sign editorialized humor ny times bylined writer even still note large fig leaf ceo joke introduced ontherecord quote talking anything nearly colorful economist rk kharealumnicaltechedu nice wired cooperate july 23 2002 natalie angier feels good chocolate tongue money bank wont make fat risk subpoena securities exchange commission hard may believe days infectious greed sabers unsheathed scientists discovered small brave act cooperating another person choosing trust cynicism generosity selfishness makes brain light quiet joy studying neural activity young women playing classic laboratory game called prisoners dilemma participants select number greedy cooperative strategies pursue financial gain researchers found women chose mutualism meism mental circuitry normally associated rewardseeking behavior swelled life longer women engaged cooperative strategy strongly flowed blood pathways pleasure researchers performing work emory university atlanta used magnetic resonance imaging take might called portraits brain hugs results really surprising us said dr gregory berns psychiatrist author new report appears current issue journal neuron went expecting opposite researchers thought biggest response would occur cases one person cooperated defected cooperator might feel treated unjustly instead brightest signals arose cooperative alliances neighborhoods brain already known respond desserts pictures pretty faces money cocaine number licit illicit delights reassuring dr berns said ways says wired cooperate study among first use mri technology examine social interactions real time opposed taking brain images subjects stared static pictures thoughtprescribed thoughts also novel approach exploring ancient conundrum humans well nice willing cooperate people barely know good deeds play fair surprisingly high percentage time scientists trouble explaining evolution competitive behavior depth breadth human altruism willingness forgo immediate personal gain longterm common good far exceeds behaviors seen even largebrained highly social species like chimpanzees dolphins difficult understand ive pointed students impressive take group young men women prime reproductive age come classroom sit perfectly comfortable civil said dr peter j richerson professor environmental science policy university california davis influential theorist field cultural evolution put 50 male 50 female chimpanzees dont know lecture hall would social explosion dr ernst fehr university zurich colleagues recently presented findings importance punishment maintaining cooperative behavior among humans willingness people punish commit crimes violate norms even chastisers take risks gain nothing serving ad hoc police survey management socalled commons smallscale communities villagers right example graze livestock commonly held land dr elinor ostrom indiana university found communities form monitoring gird cheating using fair share resource laboratory games mimic smallscale commons dr richerson said 20 30 percent coerced threat punishment cooperate fear alone highly likely inspire cooperative behavior degree observed among humans research like dr fehrs shows stick side equation newest findings present neural carrot people cooperate feels good new findings researchers studied 36 women 20 60 years old many students emory inspired participate promise monetary rewards scientists chose allfemale sample brainimaging studies looked women limited men mixture men women vast body non imaging data rely using prisoners dilemma simple elegant model reciprocity said dr james k rilling author neuron paper princeton referred e coli social psychology past results researchers said one assume neuro imaging studies men playing game would similar new findings women basic structure trial two women meet briefly ahead time one placed scanner remained outside scanning room two interacted computer playing 20 rounds game every round player pressed button indicate whether would cooperate defect answer would shown onscreen player monetary awards apportioned round one player defected cooperated defector earned 3 cooperator nothing chose cooperate earned 2 opted defect earned 1 hence mutual cooperation start finish far profitable strategy 40 woman complete mutual defection gave 20 risk woman took time became greedy little bit cooperative strategy would fall apart would emerge poorer cases women allowed pursue strategy chose cases non scanned woman would confederate researchers instructed unbeknown scanned subject defect three consecutive rounds cooperation better keep things less rarefied pretty lifelike gritty still experiments woman scanner played computer knew partner machine tests women played computer thought human researchers found rule freely strategizing women cooperated even occasional episodes defection whether free strategizers confederates necessarily fatal alliance social bond could reattained easily defector chose cooperate next couple rounds another author report dr clinton kilts said although one originally betrayed might wary result episodic defections average perexperiment take participants 30s pairs though got locked mutual defection dr rilling said analyzing scans researchers found rounds cooperation two broad areas brain activated rich neurons able respond dopamine brain chemical famed role addictive behaviors one anteroventral striatum middle brain right spinal cord experiments rats shown electrodes placed striatum animals repeatedly press bar stimulate electrodes apparently receiving pleasurable feedback starve death rather stop pressing bar another region activated cooperation orbitofrontal cortex region right eyes addition part rewardprocessing system dr rilling said also involved impulse control every round youre confronted possibility getting extra dollar defecting said choice cooperate requires impulse control significantly reward circuitry women considerably less responsive knew playing computer thought human bond mere monetary gain source contentment display concert imaging results women asked afterward summaries felt games often described feeling good cooperated expressed positive feelings camaraderie toward playing partners assuming urge cooperate extent innate among humans reinforced brains feelgood circuitry question arose remains unclear anthropologists speculated took teamwork humanitys ancestors hunt large game gather difficult plant foods rear difficult children capacity cooperate conferred survival advantage forebears yet trait willingness abide golden rule good citizen cheat steal ones neighbors uniformly distributed put ceos id like see respond dr kilts said maybe wouldnt find positive social interaction rewarding prisoners dilemma indeed httpwwwnytimescom20020723healthpsychology23coophtmlex1028415440ei1en2face896773fa4ea advertise information advertising email newsletters creative advertising opportunities new york times web please contact onlinesalesnytimescom visit online media kit httpwwwnytimescomadinfo general information nytimescom write helpnytimescom copyright 2002 new york times company httpxentcommailmanlistinfofork tue 23 jul 2002 051040 0400 edt nytimescom article nice wired cooperate