Capuchin monkeys (Cebus apella) let lesser rewards pass them by to get better rewards
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Self-control is defined as foregoing an immediate reward to gain a larger delayed reward. Methods used to test self-control comparatively include inter-temporal choice tasks, delay of gratification tasks, and accumulation tasks. To date, capuchin monkeys have shown different levels of self-control across tasks. This study introduced a new task that could be used comparatively to measure self-control in an intuitive context that involved responses that required no explicit training. Capuchin monkeys (Cebus apella) were given a choice between two food items that were presented on a mechanized, revolving tray that moved those foods sequentially toward the monkeys. A monkey could grab the first item or wait for the second, but was only allowed one item. Most monkeys in the study waited for a more highly preferred food item or a larger amount of the same food item when those came later, and they inhibited the prepotent response to grab food by not reaching out to take less-preferred foods or smaller amounts of food that passed directly in front of them first. These data confirm that the mechanisms necessary for self-control are present in capuchin monkeys and indicate that the methodology can be useful for broader comparative assessments of self-control.
KeywordsCapuchin monkeys Cebus apella Self-control Delay of gratification
This research was supported by Grant HD-060563 from the National Institute of Child Health and Human Development and by Grant BCS-0924811 from the National Science Foundation. The authors thank Betty Chan and Emilie Menzel for their assistance with this project. All applicable institutional rules and regulations regarding animal care and use were followed in the care and testing of the monkeys, and the experiment complied with all laws of the United States of America.
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