Abstract
When a visually presented stimulus flickers, its perceived duration exceeds its actual duration. This effect, the so-called time dilation, has been attributed to the number of changes in the event, so that an event with more changes is perceived to be longer. However, recent neurophysiological studies also suggest that time perception is linked to oscillatory neural activity. Here, we hypothesized that the time dilation accompanying a flickering stimulus is caused by interactions between spontaneous oscillatory neural activity and neural synchronization induced by external visual stimuli. A total of 28 subjects participated in three experiments. In all experiments, flickering stimuli with various temporal frequency spectra were presented in pairs, and a point of subjective equivalence (PSE) of 3 s was obtained by two-alternative forced choice. In Experiment 1, a PSE of 3 s with two frequencies, 10.9 Hz (alpha-frequency) and 30 Hz (gamma-frequency) was measured. In Experiment 2, the PSE was obtained with random broadband flicker (RBBF), the temporal profile of which was distributed within a specific range (8-12 or 4-30 Hz), whereas the average temporal frequency was maintained at alpha frequency range. In Experiment 3, RBBF in another range (12-16 Hz), which was not the harmonic of an alpha frequency, was compared with RBBF in an alpha frequency range. When the PSE was smaller than 3 s, time was perceived to be dilated. Time dilation was found with 10.9 and 30 Hz flickers and with 8-12 Hz RBBF, but not with 4-30 Hz RBBF or with 12-16 Hz. These results indicate that a temporal frequency of 8-12 Hz (i.e. alpha) plays a key role in time perception, and that stimulus flickering in alpha frequency, or its harmonics, causes time dilation. The contribution of the alpha frequency implies that time perception is controlled by particular temporal dynamics of synchronized neural oscillations.
Meeting abstract presented at VSS 2014