Rhesus monkeys (Macaca mulatta) monitor evolving decisions to control adaptive information seeking

Abstract

Adaptive decision making in humans depends on feedback between monitoring, which assesses mental states, and control, by which cognitive processes are modified. We investigated the extent to which monitoring and control interact iteratively in monkeys. Monkeys classified images as birds, fish, flowers, or people. At the beginning of each trial, to-be-classified images were not visible. Monkeys touched the image area to incrementally brighten the image, referred to as the brighten response. The amount by which brightness increased with each brighten response was unpredictable, and the monkeys could choose to classify the images at any time during a trial. We hypothesized that if monkeys monitored the status of their classification decision then they would seek information depending on the amount of information available. In Experiment 1, monkeys rarely used the brighten response when images were bright initially, and they used the brighten response more when earlier uses in a given trial yielded smaller amounts of information. In Experiment 2, monkeys made more brighten responses when the presented image did not belong in any of the trained categories, suggesting monkeys were sensitive to the fact that they could not reach a classification decision despite the image brightening. In Experiment 3, we found that the probability that monkeys used the brighten response correlated with their ability to correctly classify when the brighten response was not available. These findings add to the literature documenting the metacognitive skills of nonhuman primates by demonstrating an iterative feedback loop between cognitive monitoring and cognitive control that allows for adaptive information-seeking behavior.