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Alex Maier; Selective attention and perceptual suppression independently modulate contrast change detection. Journal of Vision 2010;10(7):41. doi: 10.1167/10.7.41.
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© ARVO (1962-2015); The Authors (2016-present)
Visual awareness bears a complex relationship to selective attention, with some evidence suggesting they can be operationally dissociated (Koch & Tsuchiya 2007). As a first step in the neurophysiological investigation of this dissociation, we developed a novel paradigm that allows for the independent manipulation of visual attention and stimulus awareness in nonhuman primates using a cued perceptual suppression paradigm. We trained two macaque monkeys to detect a slight decrement in stimulus contrast occurring at random time intervals. This change was applied to one of eight isoeccentric sinusoidal grating stimuli with equal probability. In 80% of trials a preceding cue at the fixation spot indicated the correct position of the contrast change. Previous studies in humans demonstrated that such cuing leads to increased selective attention under similar conditions (Posner et al. 1984). In parallel with behavioral cuing, we used binocular rivalry flash suppression (Wolfe 1984) to render the attended stimuli invisible on half the trials. The combined paradigm allows for independent assessment of the effects of spatial attention and perceptual suppression on the detection threshold of the contrast decrement, as well as on neural responses. Our behavioral results suggest that the visibility of the decrement is affected independently by attention and perceptual state. We will present preliminary electrophysiological data from early visual cortex that suggest independent contributions of these two factors to the modulation of neural responses to a visual stimulus.
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