Uncoupling Sensation and Perception in Human Time Processing

Abstract

Timing emerges from a hierarchy of computations ranging from early encoding of physical duration (time sensation) to abstract time representations (time perception) suitable for storage and decisional processes. However, the neural basis of the perceptual experience of time remains elusive. To address this, we dissociate brain activity uniquely related to lower-level sensory and higher-order perceptual timing operations, using event-related fMRI. Participants compared subsecond (500 msec) sinusoidal gratings drifting with constant velocity (standard) against two probe stimuli: (1) control gratings drifting at constant velocity or (2) accelerating gratings, which induced illusory shortening of time. We tested two probe intervals: a 500-msec duration (Short) and a longer duration required for an accelerating probe to be perceived as long as the standard (Long—individually determined). On each trial, participants classified the probe as shorter or longer than the standard. This allowed for comparison of trials with an “Objective” (physical) or “Subjective” (perceived) difference in duration, based on participant classifications. Objective duration revealed responses in bilateral early extrastriate areas, extending to higher visual areas in the fusiform gyrus (at more lenient thresholds). By contrast, Subjective duration was reflected by distributed responses in a cortical/subcortical areas. This comprised the left superior frontal gyrus and the left cerebellum, and a wider set of common timing areas including the BG, parietal cortex, and posterior cingulate cortex. These results suggest two functionally independent timing stages: early extraction of duration information in sensory cortices and Subjective experience of duration in a higher-order cortical–subcortical timing areas.

A metacognitive approach to the study of motion-induced duration biases reveals inter-individual differences in forming confidence judgements

“…In both Experiment 1 and 2, we replicated the previous finding that the duration of an interval containing a stationary visual object appears substantially compressed when compared to the duration of an interval containing a temporally modulated sensory stimulus [7][8][9][10][11][12] . An interval with an accelerating visual pattern was previously reported to appear compressed relative to an interval containing a stimulus that changes over time at a constant rate [13][14][15][16][17] , as we observed here, in both experiments. As far as the perceived duration of an interval containing a decelerating pattern is concerned, the reported effects differed across studies: some of them reported duration compression 13,45 , other studies reported no change or mild dilation 14,16 .…”

“…To our knowledge, Experiment 1 was the first attempt at measuring confidence judgements in an online study on time perception. Therefore, the sample size we deemed acceptable for Experiment 1 was based on previous psychophysical and neuroimaging studies on the effects of stimulus speed on time perception [13][14][15][16][17] , where the sample size varied between five and twenty-eight participants. We decided to opt for a larger sample size as we expected higher inter-individual variability with data collected online, under less controlled conditions.…”

“…A moving visual object is perceived to last longer than a stationary object of equal duration and with otherwise identical features [7][8][9][10][11][12] . Also, the duration of an interval containing a visual stimulus with increasing or decreasing speed over time is judged to be different from that of an interval that embeds an identical stimulus moving at a constant speed [13][14][15][16][17] , even when the two stimuli have the same average speed. The precision of duration judgements remains constant across speed profiles, indicating that differences in speed affect perceived duration, but not duration discrimination.…”

Duration reproduction in regular and irregular contexts after unilateral brain damage: Evidence from voxel-based lesion-symptom mapping and atlas-based hodological analysis

“…It is worth noting, however, that an important limitation of the present study is that only five LBD patients were included; thus, a lack of statistical power may have prevented us from detecting effects in the in the left hemisphere. Since we aimed to relate structural damage and behavioral measures of timing across the whole brain, and time perception relies on network interactions between multiple brain regions in both hemispheres (Nani et al, 2019;Teghil et al, 2019;Binetti et al, 2020), we choose to include both right and left brain damaged patients, although the two groups were not completely balanced. Present results, however, do not allow to draw definite conclusions on the role of left-sided brain regions in duration reproduction in regular and irregular contexts.…”

A purely visual adaptation to motion can differentiate between perceptual timing and interval timing

“…Empirical support for this idea comes from the observations that many time perception biases like central tendency effects (Murai & Yotsumoto, 2016), rate aftereffects (Motala et al, 2018) or duration aftereffects (Heron et al, 2012) show little or no cross-modal transfer. Evidence exists of distributed mechanisms at both cortical and subcortical levels (Binetti et al, 2020; Heron et al, 2019; Paton & Buonomano, 2018).…”