ABS 2022
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Delayed Gratification: A Grey Parrot (Psittacus erithacus) Will Wait for More (Tokens)
Irene M. Pepperberg1,2, Virginia A. Rosenberger3,4. 1The Alex Foundation, Swampscott, MA, United States; 2Hunter College ABC Program, NYC, NY, United States; 3MIT, Cambridge, MA, United States; 4Harvard Medical School, Boston, MA, United States

Delay of gratification, the ability to forgo an immediate reward and wait to gain a reward better in either 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. Several avian species have been able to wait for a better quality reward for up to 15 min, but none seem able to wait for a better quantity reward for any significant period of time in the classic "marshmallow test". Using a token system (where each wooden heart represents 1 nut piece), we demonstrated that Griffin, a Grey parrot (Psittacus erithacus)—who had previously waited up to 15 min for better quality—would now wait for better quantity, again for up to 15 min. Thus, symbolic distancing—that is, removal of the immediate presence of the hedonic item—enabled him to perform at a level comparable to that of young children on the classic test and might be a viable method for training executive function. Additional preliminary data suggest that this training did enable him subsequently to wait for a larger quantity of nuts.