Does the oblique effect influence early neural correlates of visual consciousness during binocular rivalry?
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1
Southern Cross University, Discipline of Psychology, School of Health and Human Sciences, Australia
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2
University of Leipzig, Institute for Psychology, Germany
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3
University of Sydney, Discipline of Biomedical Science, Australia
Background. Binocular rivalry refers to a powerful form or perceptual ambiguity: dissimilar images are presented to the two eyes, and the images alternate in visual consciousness. Recently, binocular rivalry has been employed to discover neural correlates of visual consciousness: brain activity that correlates with participants’ perceptual experience. The oblique effect is a decrease in performance for visual tasks when stimuli are oblique (diagonal) instead of cardinal (horizontal, vertical). This effect occurs for a wide variety of visual tasks and is known to attenuate the amplitude of the P1 and N1 components of event-related potentials (ERPs). We wondered if neural correlates of visual consciousness during binocular rivalry are affected by the oblique effect. Methods. Twelve participants were presented with binocular rivalry stimuli—one grating to one eye and an orthogonal grating to the other eye, and were asked to press buttons on a response pad indicating which of the two gratings was visible, dominant. After doing so for at least 6 seconds, we changed one of the gratings to match the grating shown to the other eye, yielding binocular fusion. Participants were aware of the change when it was made to the dominant grating and unaware when it was made to the other, suppressed grating. We measured ERPs to the change. Results. We compared ERPs from cardinal and oblique gratings when participants were aware of the change with when they were unaware. We found a bigger P1 when participants were aware than unaware: this is a neural correlate of visual consciousness. There were no differences between cardinal and oblique gratings. We found a similar result at 170 ms: a bigger N1 when participants were aware than unaware, but only for cardinal gratings. There was no effect at N1 for oblique gratings. Discussion. Consistent with previous research, our study shows a neural correlate of visual consciousness as early as 100 ms after stimulus onset. The P1 reflects sensory and perceptual processing; this correlate is indifferent to the oblique effect. We also found a neural correlate of visual consciousness at N1; this correlate reflects attentional processes and occurs only for cardinal gratings. Our experiment suggests that it is easier to find a neural correlate of visual consciousness with cardinal gratings than with oblique gratings. We propose that future research interested in probing the mysteries of visual consciousness do so with cardinal gratings.
Keywords:
Binocular Rivalry,
oblique effect,
Event-related potentials,
neural correlate of visual consciousness,
cardinal gratings,
oblique gratings
Conference:
ACNS-2013 Australasian Cognitive Neuroscience Society Conference, Clayton, Melbourne, Australia, 28 Nov - 1 Dec, 2013.
Presentation Type:
Poster
Topic:
Sensation and Perception
Citation:
Jack
BN,
Roeber
U and
O'Shea
RP
(2013). Does the oblique effect influence early neural correlates of visual consciousness during binocular rivalry?.
Conference Abstract:
ACNS-2013 Australasian Cognitive Neuroscience Society Conference.
doi: 10.3389/conf.fnhum.2013.212.00006
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Received:
15 Oct 2013;
Published Online:
25 Nov 2013.
*
Correspondence:
Mr. Bradley N Jack, Southern Cross University, Discipline of Psychology, School of Health and Human Sciences, Coffs Harbour, Australia, bradley.jack@scu.edu.au