Effects of endogenous attention on early visual processing: The role of stimulus synchrony
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1
University of Geneva, Switzerland
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2
University of Geneva, Switzerland
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3
Department of Clinical Neurology, University Hospital of Geneva, Switzerland
A growing number of studies suggest that early visual processing is not only affected by low-level perceptual attributes, but also modified by higher-order cognitive factors such as attention or emotion. Using high-density electroencephalography, we have recently demonstrated that attentional load of a task at fixation reduces the response of primary visual cortex to peripheral distractors (as indexed by the C1 component). Here, we used a similar paradigm to examine the role of an important stimulus parameter for regulating competition in resource allocation, namely temporal synchrony of target and distractor. Results show that rather than suppressing distractor responses, high attentional load elicits higher C1 amplitudes if target and distractor are presented simultaneously. These results show that under conditions of concurrent stimulation, cortical responses to irrelevant distractors in V1 are not reduced by increasing attentional load at fixation, but may be increased instead. Preliminary time-frequency analyses indicate that opposing and topographically distinct effects on alpha-band activity may underlie these differences, in accordance with recent models of alpha oscillations as a mechanism subserving active inhibition. Our findings could account for some discrepancies in demonstrating attentional effects on early visual processing in previous experiments. Moreover, they point to stimulus synchrony between target and distractor as an important modulator of the effects of endogenous attention.
Conference:
10th International Conference on Cognitive Neuroscience, Bodrum, Türkiye, 1 Sep - 5 Sep, 2008.
Presentation Type:
Poster Presentation
Topic:
Attention
Citation:
Rauss
K,
Pourtois
G,
Vuilleumier
P and
Schwartz S
S
(2008). Effects of endogenous attention on early visual processing: The role of stimulus synchrony.
Conference Abstract:
10th International Conference on Cognitive Neuroscience.
doi: 10.3389/conf.neuro.09.2009.01.104
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Received:
03 Dec 2008;
Published Online:
03 Dec 2008.
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Correspondence:
Karsten Rauss, University of Geneva, Lausanne 1015 Vaud, Switzerland, karsten.rauss@medecine.unige.ch