Self-control assessments of capuchin monkeys with the rotating tray task and the accumulation task

Abstract

Recent studies of delay of gratification in capuchin monkeys using a rotating tray (RT) task have shown improved self-control performance in these animals in comparison to the accumulation (AC) task. In this study, we investigated whether this improvement resulted from the difference in methods between the rotating tray task and previous tests, or whether it was the result of greater overall experience with delay of gratification tasks. Experiment 1 produced similar performance levels by capuchins monkeys in the RT and AC tasks when identical reward and temporal parameters were used. Experiment 2 demonstrated a similar result using reward amounts that were more similar to previous AC experiments with these monkeys. In Experiment 3, monkeys performed multiple versions of the AC task with varied reward and temporal parameters. Their self-control behavior was found to be dependent on the overall delay to reward consumption, rather than the overall reward amount ultimately consumed. These findings indicate that these capuchin monkeys’ self-control capacities were more likely to have improved across studies because of the greater experience they had with delay of gratification tasks. Experiment 4 and Experiment 5 tested new, task-naïve monkeys on both tasks, finding more limited evidence of self-control, and no evidence that one task was more beneficial than the other in promoting self-control. The results of this study suggest that future testing of this kind should focus on temporal parameters and reward magnitude parameters to establish accurate measures of delay of gratification capacity and development in this species and perhaps others.

Delayed gratification in New Caledonian crows and young children: influence of reward type and visibility

“…Few studies have explored whether delayed gratification is consistent within an individual when tested using different paradigms. In capuchins, individuals tested on the rotating tray and accumulation paradigm were more proficient on the rotating tray than accumulation task (Evans et al 2012), and also showed improved self-control overall likely due to greater experience of delayed gratification tasks (Beran et al 2016a). Future studies could similarly compare delay of gratification paradigms, including the rotating tray with other paradigms, with one another within the same sample and species, which, to our knowledge, has yet to be done with most species, including New Caledonian crows and children.…”

“…In the exchange paradigm, subjects may be required to swap rewards or tokens with an experimenter or conspecific to acquire the 'better' reward (Beran et al 1999). In the accumulation paradigm, rewards accumulate at a steady rate within the subject's reach until they touch or consume them (Beran et al 2016a). These and other delayed gratification paradigms have been used to test self-control in a number of species, including non-human primates, corvids and parrots, typically in single-species studies.…”

Chimpanzees’ understanding of social leverage

“…higher uncertainty) lead individuals towards more conservative decisions. Similarly, some studies have shown that chimpanzees and other primates such as capuchins ( Sapajus apella ) can wait more than 20 seconds (and even up to several minutes) to obtain preferred rewards while refusing less valuable options [32, 33]. Chimpanzees can also wait for partners to engage in mutual collaboration [34] but competitive scenarios, such as the one presented here, may hinder the ability to inhibit prepotent responses: chimpanzees need to divide their attention across different inputs within a limited amount of time (e.g.…”

Self‐control in crows, parrots and nonhuman primates

“…In accumulation tasks, food items accumulate at a steady rate within subject reach until they touch or begin to consume them (Beran, Perdue, et al, ). Thus, there is a trade‐off between how long the animal waits to start eating, and the total amount of reward.…”