Thinking and Deciding

456 SOCIAL DILEMMAS: COOPERATION VERSUS DEFECTION
versa. To manipulate expectations about others, subjects were told after the first trial
that the pool contained either 380 or 120 units.
In the give-some game, subjects gave less on subsequent trials when they thought
that the pool contained 380 after the first trial than when they thought it had 120.
That is, behavior was opposite from what others were perceived as doing. In the
take-some game, they took less when they thought that the pool had 380. Behavior
was the same as what others were perceived as doing. Evidently, give-some subjects
reasoned, “If nobody else is giving anything, then I’d better do it, but if others are
giving a lot, I can take advantage of them.” (Formally, this is what we have been
calling greed.) Take-some subjects seemed to reason, “If nobody else is taking, then
I’d better not take either, but if others are taking, then I can take too.” What we
have been calling “fear” seems to operate to prevent harmful actions but not harmful
omissions. (These effects were small and should be replicated, but they help to make
sense out of previous conflicting results.)
It is clear that, in many cases, people are sensitive to the behavior of others and
will do what they expect others to do. Researchers have proposed several explanations
of this tendency. One is fear, as just noted, although this may be balanced by
greed.
Another closely related motive is fairness. People do not want to be treated
unfairly by others who defect when they cooperate, nor do they want to treat others
unfairly by defecting when others cooperate.
Another motive is reciprocity. People want to “get back” at those who defect by
defecting themselves: They will pay to punish defectors (Fehr and Gächter, 2000).
People may also simply conform. Evidence of this is that they are influenced by
the behavior of others playing the same social dilemma but in a different group, so
that reciprocity is impossible (Bardsley and Sausgruber, 2005).
Finally, and more generally, people seem sensitive to social norms. They respond
to the expectations of others that norms of cooperation should be followed, and they
support those norms even at some cost to themselves (p. 395).
Tyran (2004) did a study in which subjects could contribute real money (from
the experimental payment) to a charity. In all conditions, contributions to the charity
were decided by vote. The experimental conditions varied in the number of votes
required for the contributions to be made, and (if so) in whether “no” voters had to
contribute or not. If no-votes did have to contribute, then the effect of a subject’s
vote on whether the subject had to contribute was small; the vote determined your
contribution only if it was pivotal.
Voting in favor did not depend on whether no-votes had to contribute, but they
increased as a function of the subject’s expectation that the proposal would be approved.
Evidently, subjects wanted to do their part if others voted for contributing.
It seemed that they were responding to a social norm. Most importantly, subjects
ignored the effect of their vote on the outcome for themselves.