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Accepted: 20 February 2023 / Published online: 17 March 2023
© The Psychonomic Society, Inc. 2023
Abstract
The perception appears to flow in a continuous pattern but evidence suggest that perception may involve discrete temporal sampling of peripheral cues. Stroud's perceptual moment theory proposes that perception occurs in discrete moments; however, more experimental evidence is required to support this theory. The present study characterized the decision function for asynchrony detection using variable stimulus-onset asynchronies (SOAs). Fourteen healthy volunteers (twelve males and two females), ages 21.5 ± 3.8 years (mean ± SD) participated in the study. A microcontroller was used to randomly present 280 events of paired stimuli (two red LEDs) with varying SOAs from -65 to 65 ms in steps of 5 ms. Participants were asked to press the "L" or "R" response key based on whether the left or right LED lit up first and to press the "S" key if they could not perceive the order. Asynchrony detection does not exhibit a fixed threshold value; instead, its decision function shows a monotonic increase with increasing SOAs. The asynchrony detection was 50% at an SOA of 27.8 ± 1.7 ms (mean ± SE). The curve plateaued off near 100% at SOA of 57.2 ms, which may correspond to the duration of one perceptual moment for visual perception. Data from a separate group of ten volunteers was used to validate the results. Results indicate that perception is temporally discretized rather than continuous, and the estimated duration of one perceptual moment is around 57.2 ms. This simple experiment gives objective evidence for Stroud's perceptual moment theory.
Keywords Asynchrony detection · Discrete perception · Perceptual moment · Time perception · Temporal order judgement · Simultaneity
Introduction
Conscious perception involves the processing of peripheral cues received from different sensory inputs. The phenomenal experience of the external world appears to flow in a continuous pattern like a river (James, 1890). In the late 17th century, Von Baer introduced the concept of "perceptual moment," which was based on the assumption of discrete temporal sampling of peripheral cues (Von Baer, 1862). This concept was further propagated by Stroud as perceptual moment theory (Stroud, 1967). According to this, perception is temporally partitioned into nonoverlapping equal intervals called moments. The decision of...