Neural correlates of subjective timing precision and confidence

Derek H Arnold,Kielan Yarrow,Wiremu Hohaia

doi:10.1038/s41598-020-59322-7

Derek H Arnold, Kielan Yarrow + Show 1 more

Open Access

https://doi.org/10.1038/s41598-020-59322-7

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Abstract

Humans perceptual judgments are imprecise, as repeated exposures to the same physical stimulation (e.g. audio-visual inputs separated by a constant temporal offset) can result in different decisions. Moreover, there can be marked individual differences – precise judges will repeatedly make the same decision about a given input, whereas imprecise judges will make different decisions. The causes are unclear. We examined this using audio-visual (AV) timing and confidence judgments, in conjunction with electroencephalography (EEG) and multivariate pattern classification analyses. One plausible cause of differences in timing precision is that it scales with variance in the dynamics of evoked brain activity. Another possibility is that equally reliable patterns of brain activity are evoked, but there are systematic differences that scale with precision. Trial-by-trial decoding of input timings from brain activity suggested precision differences may not result from variable dynamics. Instead, precision was associated with evoked responses that were exaggerated (more different from baseline) ~300 ms after initial physical stimulations. We suggest excitatory and inhibitory interactions within a winner-take-all neural code for AV timing might exaggerate responses, such that evoked response magnitudes post-stimulation scale with encoding success.

Highlights

Humans perceptual judgments are imprecise, as repeated exposures to the same physical stimulation can result in different decisions
We estimated physical AV timing relationships coinciding with subjective synchrony by fitting cumulative Gaussian distributions to individual data describing the proportion of audio first responses as a function of audio-visual offset
We can take the slope of individual function fits, at the 50% point of the function, as estimates of the precision of AV timing judgments

Summary

Introduction

Humans perceptual judgments are imprecise, as repeated exposures to the same physical stimulation (e.g. audio-visual inputs separated by a constant temporal offset) can result in different decisions. The precision of audio-visual (AV) timing judgments should scale with variance in patterns of brain activity, evoked by identical stimulations on different trials. These data show that distinct AV timings result in reliable differences in evoked brain activity, as decoding relies on matching evoked activity on a given trial to the average pattern of activity evoked by the same stimulation on other trials.

Results

Conclusion