Effects of intertrial reinforcers on self-control choice.
In three experiments, pigeons chose between a small amount of food delivered after a short delay and a larger amount delivered after a longer delay. A discrete-trial adjusting-delay procedure was used to estimate indifference points--pairs of delay-amount combinations that were chosen about equally often. In Experiment 1, when additional reinforcers were available during intertrial intervals on a variable-interval schedule, preference for the smaller, more immediate reinforcer increased. Experiment 2 found that this shift in preference occurred partly because the variable-interval schedule started sooner after the smaller, more immediate reinforcer, but there was still a small shift in preference when the durations and temporal locations of the variable-interval schedules were identical for both alternatives. Experiment 3 found greater increases in preference for the smaller, more immediate reinforcer with a variable-interval 15-s schedule than with a variable-interval 90-s schedule. The results were generally consistent with a model that states that the impact of any event that follows a choice response declines according to a hyperbolic function with increasing time since the moment of choice.
Mazur
J E
JE
Psychology Department, Southern Connecticut State University, New Haven 06515.
D000818:Animals; D001070:Appetitive Behavior; D002755:Choice Behavior; D003118:Color Perception; D010856:Columbidae; D003216:Conditioning, Operant; D011939:Mental Recall; D009042:Motivation; D012055:Reinforcement Schedule