Delayed gratification: A grey parrot (Psittacus erithacus) will wait for a better reward.

Delay of gratification, the ability to forgo an immediate reward to gain either better quality or quantity, has been used as a metric for temporal discounting, self-control, and the ability to plan for the future in both humans (particularly children) and nonhumans. The task involved can be parsed in several ways, such that the subjects can be required to wait, not only for a better or a larger reward, but also such that the rewards can either be in view or hidden during the delay interval. We have demonstrated that a Grey parrot (Psittacus erithacus) trained in the use of English speech could respond to the label "wait" for up to 15 min, in a task that has many similarities to those used with young children, to receive a better quality reward, whether or not the better quality reward or the experimenter was in view.