Capuchin and rhesus monkeys but not humans show cognitive flexibility in an optional-switch task

Julia Watzek,Sarah F Brosnan,Sarah M Pope

doi:10.1038/s41598-019-49658-0

Abstract

Learned rules help us accurately solve many problems, but by blindly following a strategy, we sometimes fail to find more efficient alternatives. Previous research found that humans are more susceptible to this “cognitive set” bias than other primates in a nonverbal computer task. We modified the task to test one hypothesis for this difference, that working memory influences the advantage of taking a shortcut. During training, 60 humans, 7 rhesus macaques, and 22 capuchin monkeys learned to select three icons in sequence. They then completed 96 baseline trials, in which only this learned rule could be used, and 96 probe trials, in which they could also immediately select the final icon. Rhesus and capuchin monkeys took this shortcut significantly more often than humans. Humans used the shortcut more in this new, easier task than in previous work, but started using it significantly later than the monkeys. Some participants of each species also used an intermediate strategy; they began the learned rule but switched to the shortcut after selecting the first item in the sequence. We suggest that these species differences arise from differences in rule encoding and in the relative efficiency of exploiting a familiar strategy versus exploring alternatives.

Highlights

As humans, we live in complex environments and inevitably have to rely on imperfect information when we make decisions
We assessed the ability of three primate species to break a cognitive set bias in order to use a short cut
We found that capuchin and rhesus monkeys successfully used the shortcut at high rates, soon after it first became available

Summary

Introduction

We live in complex environments and inevitably have to rely on imperfect information when we make decisions. In a clever study using chess configurations, the availability of a well-known familiar solution prevented expert players from finding the more optimal strategy and lowered their problem-solving performance to that of players three standard deviations lower in skill level[15] (an enormous decrease). This can affect important decisions we encounter in real life. Schooling in Western cultures may encourage blind repetition and reinforce the idea that a single correct solution exists for a given problem[29]

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