The Effect of Transient Location on the Resolution of Bistable Visual and Audiovisual Motion Sequences

Abstract

We examined the attention and inference accounts of audiovisual perception using the stream/bounce display, a visual stimulus wherein two identical objects move toward each other, completely superimpose, then move apart. This display has two candidate percepts: stream past each other or bounce off each other. Presented without additional visual or auditory transients, the motion sequence tends to yield the streaming percept, but when coupled with a tone or flash at the point of coincidence, the response bias flips toward bouncing. We explored two competing accounts of this effect: the attentional hypothesis and the inference hypothesis. Participants watched a series of motion sequences where a transient, when present, occurred at the moment of coincidence either colocalised with the motion sequence (congruent presentation) or on the opposite side of the display (incongruent presentation). Assuming the spotlight or zoom lens metaphor, an attentional account predicts that incongruent presentations should be associated with a higher percentage of bouncing responses than congruent presentations, while the inferential account predicts the opposite effect. No effect was found for tone-only trials. However, in trials containing a visual transient, results showed higher proportions of bounce responses within congruent over incongruent presentations, favouring the inference hypothesis over a spotlight or zoom lens attentional account.

Temporal dynamics of the flash‐induced bouncing effect

“…If that is the case, the current findings of larger postcoincidence P3 on streaming than bouncing trials in V condition but the opposite was true in VF condition might indicate that subjects were more certain about their streaming than bouncing responses when no coincident flash was presented but were more certain about their bouncing than streaming responses when the flash was presented. This interpretation fits well with our behavioral results and previous findings that streaming percept was dominant in the baseline streaming/bouncing display but bouncing percept became dominant when the additional flash was presented (Adams & Grove, ; Burns & Zanker, ; Kawabe & Miura, ; Watanabe & Shimojo, , ).…”

“…Specifically, this hypothesis proposed that the salient visual or auditory transient presented at the moment of the two disks' coincidence makes the observers genuinely see the two disks reverse their motion after coincidence and return to their original starting position. Contrary to the perceptual hypothesis, the inference hypothesis proposed that the transient‐induced bouncing effects originate from shifted cognitive bias by the transient at late decision‐making stage (e.g., Adams & Grove, ; Grove et al, ; Grove, Robertson, & Harris, ; Grove & Sakurai, ; Zeljko & Grove, ). That is, the transient appearing at the coincident moment of the two disks imitates the causal consequence (i.e., a release of sound or light energy) when two objects collide in the natural environment.…”

“…Observers typically perceived the two disks after their coincidence as either “streaming through” or “bouncing off” each other (Metzger, ), whereas the incidence of streaming percept was much higher than bouncing percept (Bertenthal, Banton, & Bradbury, ; Sekuler & Sekuler, ). Interestingly, many previous studies have found that when delivering a salient sound that was task‐irrelevant at the moment of two disks' coincidence, the dominant percept of this bistable motion display could be strikingly reversed from streaming toward bouncing (Adams & Grove, ; Dufour, Touzalin, Moessinger, Brochard, & Després, ; Grassi & Casco, ; Grove, Ashton, Kawachi, & Sakurai, ; Kawabe & Miura, ; Remijn, Ito, & Nakajima, ; Sekuler, Sekuler, & Lau, ; Watanabe & Shimojo, ). Moreover, several studies have shown that this bouncing effect could be induced not only by the auditory transient, but also by a unimodal visual flash presented at the coincident moment of the two disks (Adams & Grove, ; Burns & Zanker, ; Kawabe & Miura, ; Watanabe & Shimojo, , ).…”

“…That is, the transient appearing at the coincident moment of the two disks imitates the causal consequence (i.e., a release of sound or light energy) when two objects collide in the natural environment. According to this real‐life experience, observers can infer in a post hoc manner that the two disks were more likely to bounce off each other after the coincident transient onset (for details, see Adams & Grove, ).…”

Neural correlates of human time perception

“…This recommendation applies to all studies, not just temporal order and synchrony judgement tasks. For instance, Psychtoolbox is used in stream/bounce studies (e.g., Adams & Grove, 2018), frequency tagging studies (e.g., Toffanin et al, 2009), temporal expectation (e.g., Rohenkohl et al, 2012), temporal ventriloquism (e.g., Parise & Spence, 2008), and temporal order tasks (e.g., Cardoso-Leite et al, 2007), prior-entry studies (e.g., Weib & Scharlau, 2011), and more. All of these studies require stimuli be presented at precisely the intended timing relationship, though none of the cited studies mention verifying their stimulus timing.…”