Executive-attentional uncertainty responses by rhesus macaques (Macaca mulatta)

Abstract

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.

Figure 1

A. Percentage of uncertainty responses (solid line), sparse responses (dashed line), and dense responses (dotted line) made by capuchin monkeys (Cebus apella) in Beran et al.’s (2009) Sparse-Uncertain-Dense task. B. Percentage of middle responses (solid line), sparse responses (dashed line), and dense responses (dotted line) made by capuchins in Beran et al.’s Sparse-Middle-Dense task.

Figure 2

Percentage of uncertainty responses (solid line), sparse responses (dashed line), and dense responses (dotted line) made by the macaque Murph in Experiment 1’s Sparse-Uncertain-Dense task. A. Baseline performance. B,D. Performance with an shape-memory concurrent load. C,E. Performance with no shape-memory concurrent load.

Figure 3

A. The best-fitting predicted performance profile to the macaque Murph’s performance (Figure 2A) in a Sparse-Uncertain-Dense task with no concurrent shape-memory requirement. The percentages of uncertainty responses (solid line), sparse responses (dashed line), and dense responses (dotted line) are shown. The data were fit using formal-modeling procedures specified in the text. B. The best-fitting predicted performance profile to the macaque Murph’s performance (Figure 2B) in a Sparse-Uncertain-Dense task with a concurrent shape-memory requirement. The data were modeled and are depicted in the same way.

Figure 4

A. Murph’s uncertainty-response percentage for trial levels 21–40, by sequential trial block, in the five phases of Experiment 1 (from left to right: baseline, concurrent-load 1, control 1, concurrent-load 2, and control 2). The Y-axis is scaled to the maximum uncertainty-response percentage. B. Lou’s uncertainty-response percentages, depicted in the same way.

Figure 5

Percentage of uncertainty responses (solid line), sparse responses (dashed line), and dense responses (dotted line) made by the macaque Lou in Experiment 1’s Sparse-Uncertain-Dense task. A. Baseline performance. B. Performance with a shape-memory concurrent load. C. Performance with no shape-memory concurrent load.

Figure 6

A. The best-fitting predicted performance profile to the macaque Lou’s performance (Figure 5A) in a Sparse-Uncertain-Dense task with no concurrent shape-memory requirement. The percentages of uncertainty responses (solid line), sparse responses (dashed line), and dense responses (dotted line) are shown. The data were fit using formal-modeling procedures specified in the text. B. The best-fitting predicted performance profile to the macaque Lou’s performance (Figure 5B) in a Sparse-Uncertain-Dense task with a concurrent shape-memory requirement. The data were modeled and are depicted in the same way.

Figure 7

Percentage of uncertainty responses (solid line), sparse responses (dashed line), and dense responses (dotted line) made by the macaque Murph in Experiment 2’s Sparse-Uncertain-Dense task. A. Performance with a spatial-memory concurrent load. B. Performance with no spatial-memory concurrent load. C. Performance with a spatial-memory concurrent load.

Figure 8

A. Murph’s uncertainty-response percentage for trial levels 21–40, by sequential trial block in the three phases of Experiment 2 (from left to right: concurrent-load 1, control 1, concurrent-load 2). The Y-axis is scaled to his maximum uncertainty-response percentage. B. Lou’s uncertainty-response percentages, depicted in the same way.

Figure 9

A. Percentage of uncertainty responses (solid line), sparse responses (dashed line), and dense responses (dotted line) made by the macaque Lou in Experiment 2’s Sparse-Uncertain-Dense task. A. Performance with a spatial-memory concurrent load. B. Performance with no spatial-memory concurrent load. C. Performance with a spatial-memory concurrent load.

Figure 10

A formal simulation illuminating the psychophysical situation in the sparse-middle-dense task of Experiment 3. The simulated subject performed 600,000 trials in that task with a Gaussian perceptual error of 6 steps along the continuum and with sparse-uncertain and uncertain-dense criteria, respectively, of 26 and 36. The graph shows the proportion of all trials at each density level on which the stimulus would have been misclassified into the wrong perceptual category (e.g., an objectively middle stimulus perceived and classified as sparse or dense).

Figure 11

Percentage of middle responses (solid line), sparse responses (dashed line), and dense responses (dotted line) made by the macaque Hank in Experiment 3’s Sparse-Middle-Dense task. A,C. Performance without a concurrent cognitive load. B,D. Performance with a concurrent cognitive load.

Figure 12

A. Hank’s middle-response percentage for trial levels 21–40, by sequential trial block in the four phases of Experiment 2 (from left to right: baseline, concurrent-load 1, control, concurrent-load 2). The Y-axis is scaled to his maximum middle-response percentage. B. Gale’s middle-response percentages, depicted in the same way.

Figure 13

Percentage of middle responses (solid line), sparse responses (dashed line), and dense responses (dotted line) made by the macaque Gale in Experiment 3’s Sparse-Middle-Dense task. A,C. Performance without a concurrent cognitive load. B,D. Performance with a concurrent cognitive load.

Figure 14

A,B. Percentage of uncertainty responses (solid line), sparse responses (dashed line), and dense responses (dotted line) made by macaques Murph and Lou in their baseline performance and in their first phase of concurrent-load testing. C,D. Percentage of middle responses (solid line), sparse responses (dashed line), and dense responses (dotted line) made by macaques Hank and Gale in their baseline performance and in their first phase of concurrent-load testing.