Serial dependence in time and numerosity perception is dimension-specific

Abstract

The perception of a visual event (e.g., a flock of birds) at the present moment can be biased by a previous perceptual experience (e.g., the perception of an earlier flock). Serial dependence is a perceptual bias whereby a current stimulus appears more similar to a previous one than it actually is. Whereas serial dependence emerges within several visual stimulus dimensions, whether it could simultaneously operate across different dimensions of the same stimulus (e.g., the numerosity and the duration of a visual pattern) remains unclear.Here we address this question by assessing the presence of serial dependence across duration and numerosity, two stimulus dimensions that are often associated and can bias each other. Participants performed either a duration or a numerosity discrimination task, in which they compared a constant reference with a variable test stimulus, varying along the task-relevant dimension (either duration or numerosity). Serial dependence was induced by a task-irrelevant inducer, that is, a stimulus presented before the reference and always varying in both duration and numerosity. The results show systematic serial dependencies only within the task-relevant stimulus dimension, that is, stimulus numerosity affects numerosity perception only, and duration affects duration perception only. Additionally, at least in the numerosity condition, the task-irrelevant dimension of the inducer (duration) had an opposite, repulsive effect. These findings thus show that attractive serial dependence operates in a highly specific fashion and does not transfer across different stimulus dimensions. Instead, the repulsive influence, possibly reflecting perceptual adaptation, can transfer from one dimension to another.

Different modality-specific mechanisms mediate perceptual history effects in vision and audition

“…Regarding the feature selectivity of serial dependence in different modalities, our prediction was that while it should be weak or absent in vision -in line with previous studies in magnitude perception (Fornaciai & Park, 2019b;Togoli et al, 2021), audition might instead show a more pronounced selectivity, especially when it comes to a fundamental and salient dimension like the pitch of a pure tone. Regarding the spatial selectivity of the effect, we instead predicted an opposite pattern of effects, in line with the intrinsic properties of audition and vision.…”

“…Overall, this different pattern of effects suggests that modality-specific processing mechanisms, working according to the intrinsic properties of different modalities, likely mediate the behavioural effect of perceptual history. Finally, the existence of independent mechanisms involved with perceptual history is also consistent with results showing that serial dependence does not work cross-modally (i.e., the numerosity of an auditory stimulus does not affect the perceived numerosity of a visual stimulus; Fornaciai & Park, 2019b), and, even within the same modality, does not work across different but related dimensions such as time and numerosity (Togoli et al, 2021).…”

“…If perceptual history truly operates at the level of perceptual processing, then we predict the existence of at least partially independent mechanisms operating before distinct sensory pathways converge onto associative brain areas. To address this possibility, we focused on time perception, and assessed the behavioural and neural signature of perceptual history effects in a duration discrimination task (Togoli et al, 2021). Time perception was specifically chosen since, differently from other perceptual domains more often studies in this context (i.e., orientation or numerosity perception), interval duration can similarly be delivered as a visual or an auditory input, which is crucial in order to compare the results across different modalities.…”

“…Across all experiments, participants performed a duration discrimination task, comparing the duration of a constant reference stimulus (200 ms) against a variable probe with different durations randomised across trials (100, 140, 200, 280, or 400 ms). To induce perceptual history effects, we presented a task irrelevant “inducer” stimulus before the reference, which could be either 100 ms or 400 ms long, following a similar procedure already used in previous studies (e.g., (Fornaciai & Park, 2018b; Togoli et al, 2021)). Each trial started with participants keeping their gaze on a central fixation point.…”

Serial Dependence of Emotion Within and Between Stimulus Sensory Modalities

“…Indeed, numerous studies have shown that our percept is also biased by information we processed in our immediate past (Alais et al, 2017;Fritsche et al, 2017;Harvey et al, 2014;Kiyonaga et al, 2017;Liberman et al, 2014;Taubert et al, 2016;Van der Burg & Goodbourn, 2015;Xia et al, 2016). Such serial dependencies have been observed across different modalities and tasks (e.g., Fornaciai & Park, 2019;Lau & Maus, 2019;Liberman et al, 2018;Manassi et al, 2018;Togoli et al, 2021)). There also appears to be a serial effect for the affective appraisal of emotional stimuli.…”