The value of an outcome is affected both by the delay until its receipt (delay discounting) and by the likelihood of its receipt (probability discounting). Despite being well-described by the same hyperboloid function, delay and probability discounting involve fundamentally different processes, as revealed, for example, by the differential effects…

Parallel experiments with rats and pigeons examined reasons for previous findings that in choices with probabilistic delayed reinforcers, rats' choices were affected by the time between trials whereas pigeons' choices were not. In both experiments, the animals chose between a standard alternative and an adjusting alternative. A choice of the…

This study focused on the processes occurring during the waiting period in delay of gratification situations. Sixty-four middle class preschool children chose between waiting for a preferred item and receiving a less desired item immediately. The items were of different classes, i. e., one food and one toy, and subjects waited with one, both, or…