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 that 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 cannot 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 be either in the same or a different location, which led to different sensory responses because of neural repetition suppression. Crucially, changes and repetitions were fully predictable, which allowed us to explore effects of sensory response magnitude without changes in 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 ERPs (P2) and pupil constriction, both of which have been related to responses in the 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.

Memory for Stimulus Duration Is Not Bound to Spatial Information

“…This behavioral bias coincided with ERP differences in response to the offset markers of "Same" and "Opposite" markers, a finding that warrants more thorough exploration beyond the scope of this study. We discuss this observation in more detail in a companion paper (Kruijne et al, 2021).…”

“…The EEG results presented below offer tentative evidence that this finding relates to the neural response evoked by the offset marker in "Opposite" blocks. However, as this does not immediately relate to the current research question, we have presented a more in-depth investigation elsewhere (Kruijne, Olivers, & van Rijn, 2021). In this paper, EEG analyses will focus on neural markers for memory maintenance and retrieval.…”

Change biases identify the features that drive time perception.

“…In particular, we found that change bias effects on duration perception were found with visual stimuli that differed in location, size and numerosity, but not with any of the other tested feature dimensions. 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, 2021). The results suggested that sensory responses to the offset marker were attenuated upon repetition compared to changes, which in turn affected the perceived duration.…”

“…This hypothesis-driven model makes several assumptions that were based on our earlier findings (Kruijne et al, 2021). Most importantly, the model assumes that experimental conditions (trial type and block type) only differ with respect to the shift of the psychometric curves, but not their slope.…”

“…Sample size and power. Sample sizes were based on a GLMM fit to earlier results (Kruijne et al, 2021, Experiment 2) and were validated using power analyses with the 'simr' package (Brysbaert & Stevens, 2018;Green & MacLeod, 2016). We simulated 250 experiments with this model, based on the current number of trials per block type (160), using a conservative effect size estimate, four times smaller than what had been observed.…”