![]() ![]() figural coherence) also can impact rivalry dynamics.įor these reasons, rivalry has become a paradigm phenomenon for pursuing the NCsC, at least as that term applies to visual awareness (e.g. (iv) Fluctuations in perception during rivalry can be influenced by manipulating simple stimulus variables such as contrast or contour density, and some evidence suggests that object-related properties of images (e.g. We can think of several possible reasons why scientists have been attracted to this particular form of perceptual bistability. This incongruence causes the observer to perceive only one of the images at a time, with perception alternating between images every few seconds. In binocular rivalry, one eye views a given image while a different image is presented to the corresponding region of the other eye. Within the stable of visual phenomena that have been deployed to implement this strategy, binocular rivalry stands out as a real workhorse. ![]() ![]() ![]() This combination of unchanging physical stimulation and varying awareness is valuable because it allows a comparison of neural events between moments that differ specifically with regard to conscious state, and not with regard to physical input. These fluctuations in visual awareness occur because these objects or events are ambiguous with respect to their identity and, therefore, plausibly support conflicting interpretations. In pursuit of clues for identifying NCsC, psychologists and neuroscientists have focused especially on a variety of compelling visual phenomena for which one's conscious percept changes over time even though the objects or events one is viewing remain unchanged. These are the brain events that underlie the conscious states experienced by sentient observers, the ‘minimal neuronal mechanisms jointly sufficient for one specific conscious percept’. Central to this topic is the notion ‘neural correlates of consciousness’ (NCsC). The topic of this special issue-perceptual awareness and its neural basis-has intrigued philosophers for centuries, and in recent years it has become a core focus within cognitive neuroscience. Our ideas are presented within the framework of four questions about the use of rivalry for this purpose: (i) what constitutes an adequate comparison condition for gauging rivalry's impact on awareness, (ii) how can one distinguish abolished awareness from inattention, (iii) when one obtains unequivocal evidence for a causal link between a fluctuating measure of neural activity and fluctuating perceptual states during rivalry, will it generalize to other stimulus conditions and perceptual phenomena and (iv) does such evidence necessarily indicate that this neural activity constitutes a neural correlate of consciousness? While arriving at sceptical answers to these four questions, the essay nonetheless offers some ideas about how a more nuanced utilization of binocular rivalry may still provide fundamental insights about neural dynamics, and glimpses of at least some of the ingredients comprising neural correlates of consciousness, including those involved in perceptual decision-making. This essay critically examines the extent to which binocular rivalry can provide important clues about the neural correlates of conscious visual perception. ![]()
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