Abstract
The neural processes underlying human timing sensitivity, and its variance, remain poorly understood. One possibility is that relative timing is encoded in terms of when signals reach some critical structure(s) in the brain. This possibility, often called 'brain time', remains controversial. According to the brain time hypothesis, variable encoding dynamics from trial to trial should result in variable decisions being made about the timings of identical stimulations, resulting in imprecision. To assess this possibility, we measured the dynamics of audio and visual evoked brain activity, using electroencephalography, to see if these could predict audio-visual timing precision. We found that the precision of an individuals' audio-visual timing decisions could be predicted by the degree of inter-trial variance in their evoked brain activity following identical stimulations. The relevant variance was distinct, detectable from specific sensors, and it did not predict control task performances – judgments of visual pattern frequency or auditory signal origin. These results are consistent with the brain time hypothesis. They are broadly inconsistent with philosophically inspired accounts, which suggest that human timing is shaped by compensatory strategies that counter the influence of brain dynamics.
Meeting abstract presented at VSS 2017