Subjective time is predicted by local and early visual processing

Abstract

Time is as pervasive as it is elusive to study, and how the brain keeps track of millisecond time is still unclear. Here we studied the mechanisms underlying duration perception by looking for a neural signature of subjective time distortion induced by motion adaptation. We recorded electroencephalographic signals in human participants while they were asked to discriminate the duration of visual stimuli after translational motion adaptation. Our results show that distortions of subjective time can be predicted by the amplitude of the N200 event-related potential and by the activity in the Beta band frequency spectrum. Both effects were observed from occipital electrodes contralateral to the adapted stimulus. Finally, a multivariate decoding analysis highlights the impact of motion adaptation throughout the visual stream. Overall, our findings show the crucial involvement of local and low-level perceptual processes in generating a subjective sense of time.

The neural signature of magnitude integration between time and numerosity

“…With EEG, we aimed to further address the neural signature of these effects, and assess the existence of a common magnitude processing stage mediating the interaction between numerosity and duration. The analysis of EEG data was performed by considering the average of a set of six occipito-parietal channels of interest in both the numerosity and duration task conditions (O1, PO3, POz, PO4, O2, and Oz), chosen according to previous results (Fornaciai et al, 2017;Park et al, 2016;Tonoyan et al, 2020). Figure 4 shows the ERPs evoked by either different numerosities or different durations, separately for the two task conditions.…”

“…Specifically, based on previous studies, we selected a series of six occipito-parietal channels, including O1, PO3, POz, PO4, O2, and Oz. Those channels were selected based on previous findings showing a signature of numerosity processing at occipito-parietal electrodes (Fornaciai et al, 2017; Park et al, 2016), and based on a recent study from our group showing a signature of distortions of perceived duration in a similar set of channels (Tonoyan et al, 2020). The rationale for this choice was to use the exact same set of channels when assessing the brain responses to both duration and numerosity, and their potential interaction, thus decreasing the degrees of freedom of the analysis.…”