Action-specific disruption of perceptual confidence

Abstract

Theoretical models of perception assume that confidence is related to the quality or strength of sensory processing. Counter to this intuitive view, we showed in the present research that the motor system also contributes to judgments of perceptual confidence. In two experiments, we used transcranial magnetic stimulation (TMS) to manipulate response-specific representations in the premotor cortex, selectively disrupting postresponse confidence in visual discrimination judgments. Specifically, stimulation of the motor representation associated with the unchosen response reduced confidence in correct responses, thereby reducing metacognitive capacity without changing visual discrimination performance. Effects of TMS on confidence were observed when stimulation was applied both before and after the response occurred, which suggests that confidence depends on late-stage metacognitive processes. These results place constraints on models of perceptual confidence and metacognition by revealing that action-specific information in the premotor cortex contributes to perceptual confidence.

Keywords: monitoring; motor processes; open data; perception.

Fig. 1.

Example trial sequence from (a) Experiment 1 and (b) Experiment 2. In Experiment 1, participants briefly viewed two noise patches, on one of which a grating was superimposed, and subsequently had to indicate the side on which the grating was presented. In Experiment 2, participants briefly viewed a centrally presented grating and then had to indicate whether it had been horizontally or vertically oriented. A single pulse of transcranial magnetic stimulation (TMS) was applied either 100 ms after stimulus onset (preresponse condition) or immediately after participants’ response (postresponse condition). The hemisphere that received TMS was counterbalanced across participants. Following each response, participants were asked to provide a confidence rating on a scale from 1 (low confidence) to 4 (high confidence) 1,500 ms after the offset of the stimulus. RT = response time.

Fig. 2.

Mean proportion of correct responses in the group that received transcranial magnetic stimulation (TMS) in the dorsal premotor cortex in (a) Experiment 1 and (b) Experiment 2. Results are shown separately for congruent and incongruent trials when TMS was delivered before or after participants’ response. In (b), results are also shown for a control condition (in which TMS was not applied). Error bars reflect standard errors of the mean.

Fig. 3.

Confidence ratings in the group that received transcranial magnetic stimulation (TMS) in the dorsal premotor cortex in (a) Experiment 1 and (b, c) Experiment 2. The graphs in (a) and (b) show raw mean confidence ratings as a function of stimulation condition, response accuracy, and congruence. In (b), results are also shown for a control condition (in which TMS was not applied) for trials responded to correctly and incorrectly. Dashed lines reflect mean confidence in the control condition. The graph in (c) shows baseline-corrected confidence data in Experiment 2 as a function of response accuracy. Baseline-corrected confidence data were calculated by subtracting mean raw confidence ratings on no-TMS trials from mean raw confidence ratings on TMS trials. Error bars reflect standard errors of the mean. Asterisks indicate a significant difference between TMS conditions (p < .05).

Fig. 4.

Metacognitive efficiency (meta-d′/d′) as a function of stimulation condition and congruence in the group that received transcranial magnetic stimulation (TMS) in the dorsal premotor cortex, pooled across Experiments 1 and 2. For each data bar, error bars on the left reflect standard errors of the mean, and error bars on the right reflect bootstrapped 95% confidence intervals. The dashed line indicates the optimal meta-d′/d′ value. Asterisks indicate a significant difference between conditions (p < .01).