Results that point to animals’ metacognitive capacity bear a heavy burden given the potential for competing behavioral descriptions. This article uses formal models to evaluate the force of these descriptions. One example is that many existing studies have directly rewarded so-called “uncertainty” responses. Modeling confirms that this practice is an interpretative danger because it supports associative processes and encourages simpler interpretations. Another example is that existing studies raise the concern that animals avoid difficult stimuli not because of uncertainty monitored but because of aversion given error-causing or reinforcement-lean stimuli. Modeling also justifies this concern and shows that this problem is not addressed by the common practice of comparing performance on Chosen and Forced trials. The models and related discussion have utility for metacognition researchers and theorists broadly because they specify the experimental operations that will best indicate a metacognitive capacity in humans or animals by eliminating alternative behavioral accounts.

Some studies of nonhuman animals’ metacognitive capacity encourage competing low-level, behavioral descriptions of trial-decline responses by animals in uncertainty-monitoring tasks. To evaluate the force of these behavioral descriptions, six capuchin monkeys were presented with two density-discrimination tasks between sparse and dense stimuli. In one task, difficult trials with stimuli near the middle of the density continuum could be declined through an “uncertainty” response. In the other task, making a “middle” response to the same stimuli was rewarded. In Experiment 1, capuchins essentially did not use the uncertainty response, but they did use the middle response. In Experiment 2, we replicated this result with 5 of 6 monkeys while equating the overall pace and reinforcement structure of the two tasks, although one monkey also showed appropriate use of the uncertainty response. These results challenge a purely associative interpretation of some uncertainty-monitoring performances by animals, while sharpening the theoretical question concerning the nature of the psychological signal that occasions uncertainty responses.

Some metacognition paradigms for nonhuman animals encourage the alternative explanation that animals avoid difficult trials based only on reinforcement history and stimulus aversion. To explore this possibility, we placed humans and monkeys in successive uncertainty-monitoring tasks that were qualitatively different, eliminating many associative cues that might support transfer across tasks. In addition, task transfer occurred under conditions of deferred and rearranged feedback-both species completed blocks of trials followed by summary feedback. This ensured that animals received no trial-by-trial reinforcement. Despite distancing performance from associative cues, humans and monkeys still made adaptive uncertainty responses by declining the most difficult trials. These findings suggest that monkeys' uncertainty responses could represent a higher-level, decisional process of cognitive monitoring, though that process need not involve full self-awareness or consciousness. The dissociation of performance from reinforcement has theoretical implications concerning the status of reinforcement as the critical binding force in animal learning.

The uncertainty response has been influential in studies of human perception, and it is crucial in the growing research literature that explores animal metacognition. However, the uncertainty response’s interpretation is still sharply debated. The authors sought to clarify this interpretation using the dissociative technique of cognitive loads imposed on ongoing discrimination performance. Four macaques (Macaca mulatta) performed a Sparse-Dense discrimination within which an uncertainty response let them decline difficult trials or a middle response let them identify middle stimuli. Concurrent memory tasks were occasionally overlain on ongoing discrimination performance. The concurrent tasks disrupted macaques’ uncertainty responses far more than their sparse, middle, or dense discrimination responses. This dissociation suggests that the uncertainty response is a higher-level, decisional response that is particularly dependent on working memory and attentional resources. This is consistent with the theoretical possibility that the uncertainty response is an elemental behavioral index of uncertainty monitoring or metacognition.