When more means less: factors affecting human self-control in a local versus global choice paradigm

Abstract

Adult human participants experienced 200 trials in which they repeatedly chose between two immediately available rewards of different magnitudes (points exchangeable for money). Although choosing the larger reward always resulted in more points per trial, choosing the smaller reward increased the magnitude of both rewards on the next trial.

Thus consistent choice of the smaller reward resulted in a greater average number of points overall. This effect on global (overall) reinforcement rate was gradual and difficult to perceive by comparison with the (opposed) difference in points between the two alternatives on a given trial (local rate). Participants generally preferred the larger reward and thus failed to maximize the global reinforcement rate.

Preference for this higher local rate of reinforcement increased when the difference in local rates was larger. However, when the salience of the global contingency was enhanced by providing cognitive or social comparative information, participants chose the larger reward less often and thus increased global reinforcement rate.