Neural repetition suppression modulates time perception: Evidence from electrophysiology and pupillometry

Abstract

Human time perception is malleable and subject to many biases. For example, it has repeatedly been shown that stimuli that are physically intense or that are unexpected seem to last longer. Two competing hypotheses have been proposed to account for such biases: one states that these temporal illusions are the result of increased levels of arousal which speeds up neural clock dynamics, whereas the alternative ‘magnitude coding’ account states that the magnitude of sensory responses causally modulates perceived durations. Common experimental paradigms used to study temporal biases can not dissociate between these accounts, as arousal and sensory magnitude covary and modulate each other. Here, we present two temporal discrimination experiments where two flashing stimuli demarcated the start and end of a to-be-timed interval. These stimuli could either be in the same or in a different location, which led to different sensory responses due to neural repetition suppression. Crucially, changes and repetitions were fully predictable, which allowed us explore effects of sensory response magnitude without impacting arousal or surprise. Intervals with changing markers were perceived as lasting longer than those with repeating markers. We measured EEG (Experiment 1) and pupil size (Experiment 2), and found that temporal perception was related to changes in event-related potentials (P2) and pupil constriction, both of which have been related to responses in sensory cortex. Conversely, correlates of surprise and arousal (P3 amplitude and pupil dilation) were unaffected by stimulus repetitions and changes. These results demonstrate, for the first time, that sensory magnitude affects time perception even under constant levels of arousal.

Change biases identify the features that drive time perception

“…The results indicate that for the first three of those dimensions, changes between the start-and end-marker of an interval resulted in a dilation of perceived duration compared to trials where the start-and end-marker were the same. These findings show that the 'change bias' that we found in earlier work (Kruijne et al, 2020) is a general finding that is not limited to changes in location. At the same time, the results suggest that the change bias shows selectivity, as changes in Faces, Orientation and Luminance did not affect time perception in the same way.…”

“…In an earlier study we have demonstrated that the change bias manifests when stimuli marking the start and end of an interval either repeat or change in location (Kruijne et al, 2020). The results suggested that sensory responses to the offset marker were attenuated upon repetition compared to changes, which in turn affected the perceived duration.…”

“…Recently, we have presented an experimental paradigm that might overcome this convolution (Kruijne et al, 2020). In this study, participants timed intervals that were presented by means of briefly flashing on-and offset markers (cf.…”

“…This primary analysis was based on a hypothesis-driven model, which makes several assumptions derived from earlier observations (Kruijne et al, 2020). Most importantly, the model relies on the assumption that experimental conditions (trial type and block type) could affect the shift of the psychometric curves, but not their slope.…”

“…All interval markers (including those in reference trials) were dark green open squares (as in Kruijne et al, 2020), which were somewhat less straining on the eyes than the white FEATURE CHANGES AFFECT TIME PERCEPTION 21 squares used in Experiment 1. In Size-blocks, this square had sides of either 3.85°or 11.41, which constitutes a change of ±50% with respect to its size in reference trials and Location-blocks (7.67°).…”