W6 L2 human cooperation Flashcards
Experiment showing that cooperation is is costly
Lost letter experiments, in which stamped letters are left on the pavement, examine ‘altruism’, because posting the ‘lost letter’ is costly and unlikely to result in a reward
Altruism is strongly ‘context’ dependant: letters dropped in the poorest neighbourhoods having 91% lower odds of being returned than letters dropped in the wealthiest neighbourhoods
Another experiment with letter
300 self-addressed, letters (150 stamped, 150 not stamped) dropped on rain-free
weekdays in 15 residential suburbs of Perth (WA) that varied with measures of ‘wealth’.
-stamp are more likely to return
-wealthier suburbs are more likely to return
Way that human cooperation might have evolve
- kin selection
- direct reciprocity
- indirect reciprocity
- partner choice
Hamilton’s Rule:
Kin selection (i.e., selection at the genetic level) will favour cooperative, or altruistic behaviour if: br - c > 0
where
* b = benefit to beneficiary; * c = cost to donor; and
* r = coefficient of relatedness (degree to which actor and beneficiary share genes)
Hamilton’s Rulemakes the simple prediction that individuals are more likely to direct cooperative or altruistic behaviour toward relatives than toward non-relatives.
Kin directed care, manifestation of Hamilton’s rule
The most obvious manifestation of Hamilton’s Rule is that infants are nurtured by their parents than by others. But Hamilton’s Rule also predicts that individuals can further increase their inclusive fitness by extending care to their relatives
Cooperation in the context of hunter-
gatherer societies
-Small, mobile units comprising several families Food shared, often among non-genetic kin
-Diet requires foraging/processing technology
-Longer juvenile dependency relative to birth interval, favours ‘cooperative care’ Cooperation not necessarily directed to kin
Direct reciprocity: tests with the
Prisoner’s Dilemma
Two prisoners
* unable to communicate with each other * must choose to (a) testify against the other (defect) or (b) remain silent (cooperate). Their sentence depends upon what both prisoners claim
* if one testifies, and the other remains silent, the former goes free and the other gets 3 years (best average pay-off)
* if each testifies against the other, then both get two years
* if both remain silent, both get one year
-when played multiple time, the more punishment used, the lower pay-offs it is. Winner rarely punish
Indirect reciprocity
Downstream reciprocity is built on reputation; upstream reciprocity is harder to understand. Both could be interpreted as a misdirected act of gratitude.
Chimpanzee indirect reciprocity study
During the training phase, the chimpanzee learnt that by sending the food to another, recipient chimpanzee, it may be subsequently rewarded with a slightly larger food item.
The decision to reward the subject chimpanzee was made by the experimenters, but the experimental apparatus made it seem like it was the recipient chimpanzee’s decision
-Each subject chimpanzee was then paired with three trustworthy recipient chimpanzees (donating a food item was always rewarded with a larger food item) and three non-trustworthy recipient chimpanzees (donating a food item was never rewarded).
Result of the chimp indirect study
-cooperation with the trust-worthy chimpanzee
Indirect reciprocity game and reputation
Indirect reciprocity game — individuals given £3, paired and randomly designated donor (give 50p) or receiver (obtain £1, the difference provided by the experimenters).
Giving increases an image score, which was displayed at the end of the session. Players played another player once only, so there was no opportunity for direct reciprocity
indirect reprocity game result
- The influence of the receivers’ image score on the donors’ decision:
receivers who got something had a higher image score than those that got nothing. - Similarly, the donors’ decisions were also influenced by their own image score: donors with a low image score were more likely to give something (and thus improve their image score)
Prisoner dilemma with direct reciprocity game
Direct reciprocity game – Individuals were given £3, paired and randomly
designated donor (give 50p) or receiver (obtain £1, the difference provided by the experimenters).
Individuals then played Prisoners’ Dilemma six times, with their image score from the previous session revealed.
Reputation (image) influences long term outcome of playing prisoners’ dilemma (direct reciprocity game)
Perceived reputation influences
cooperation
Two kinds of photographs (eye or flower) were placed above the ‘honesty box’ for contributions to tea, coffee and milk in the tea-room of a University psychology department.
The perception of being watched clearly influences a genuine commitment to cooperation
Public goods game
In this game, individuals ‘donate’ an amount of their money, which is subsequently increased by a factor, and the resulting amount is distributed evenly
