Motion-induced blindness continues outside visual awareness and without attention.

Kevin C Dieter,Duje Tadin,Joel Pearson

doi:10.1038/srep11841

Kevin C Dieter, Duje Tadin + Show 1 more

Open Access

https://doi.org/10.1038/srep11841

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Abstract

Visual phenomena demonstrating striking perceptual disappearances of salient stimuli have fascinated researchers because of their utility in identifying neural processes that underlie subjective visibility and invisibility. Motion-induced blindness (MIB) is appealing for such purposes because it, like a class of ostensibly related paradigms such as binocular rivalry, features periods of unequivocal subjective disappearances despite constant physical stimulation. It remains unclear, however, exactly how the mechanisms that cause MIB are related to subjectively observed fluctuations in visual awareness. To address this question, we used continuous flash suppression (CFS) to present the MIB stimulus outside visual awareness. Results indicated that MIB occasionally reappeared from suppression with its salient yellow target absent. To quantify this observation, we measured reaction times (RTs) to detect the yellow dot target following visible or perceptually suppressed MIB and indeed found no difference in RTs between these conditions. We also provide evidence that MIB fluctuations can occur without attention. In sum, these experiments indicate that MIB fluctuations are effectively changes in stimulus strength, which under typical conditions result in unmistakable subjective disappearances, but are not inherently fluctuations in stimulus visibility. More broadly, these results challenge the assumed privileged link between bistable stimuli and visual awareness.

Highlights

motion-induced blindness (MIB) fluctuations can be understood as fluctuations in stimulus strength, which under some conditions result in visibility fluctuations
Our main findings indicate that critical dynamics underlying MIB continue when MIB is perceptually suppressed
This result supports the hypothesis that MIB fluctuations are essentially fluctuations in stimulus strength, which under some conditions result in visibility fluctuations but are not inherently visibility fluctuations

Summary

Introduction

On the other extreme (Fig. 1c), CFS has no impact on MIB dynamics, resulting in identical dynamics during visible and invisible presentations of MIB. To differentiate between scenarios outlined, we asked observers to detect the target item following ‘visible’ (Fig. 2a) or ‘suppressed’ (Fig. 2b) periods of MIB This allowed us to infer whether MIB dynamics continue or halt during the time period of interest (i.e., CFS or typical viewing). Preliminary tests revealed that upon the removal of the CFS stimulus, the blue crosses of the MIB stimulus always became visible, but occasionally without the salient yellow target dot. To quantify this revealing informal observation, we implemented a simple reaction time task. To test the generalizability of our main finding, we investigated MIB under conditions of inattention[10] (Fig. 2c,d)

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