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Antoine Barbot, Valentin Wyart, Marisa Carrasco; Spatial and feature-based attention differentially affect the gain and tuning of orientation-selective filters. Journal of Vision 2014;14(10):703. doi: 10.1167/14.10.703.
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Background: Spatial and feature-based attention improve performance in contrast sensitivity tasks. Two mechanisms have been proposed to explain how attention affects visual responses: gain and tuning changes. Some studies indicate that spatial attention only affects the gain of the population response, whereas feature-based attention affects both the gain and tuning. Here, we directly assessed the influences of spatial and feature-based attention on the gain and tuning of orientation-selective responses. Using a reverse-correlation technique, we quantified how signal-like fluctuations in stimulus energy predict trial-to-trial variability in participants' judgments, and investigated how both types of attention affect the energy sensitivity of orientation-selective filters. Procedure: Two noise patches were presented to the left and right of fixation. Each patch could contain a Gabor signal embedded in Gaussian noise. When present (50% of the trials), the signal could be vertical or horizontal. At the beginning of each trial, an informative (66% valid) central pre-cue indicated the relevant location (spatial) as well as the signal orientation (feature-based). To eliminate location and feature uncertainty, a post-cue indicated the target location as well as its orientation (for both present and absent trials). We used a reverse-correlation technique to quantify how both types of attention affect the energy sensitivity profile of orientation-selective filters. Results: Spatial and feature-based attention improved performance (d') in an additive and independent way. Moreover, both types of attention increased the energy sensitivity of orientation-selective filters, but in dissociable ways. Whereas spatial attention only increased the gain, feature-based attention increased the gain and sharpened the tuning of orientation-selective filters. Conclusion: Using reverse-correlation, we provide direct evidence regarding how spatial and feature-based attention affect the gain and tuning of orientation-selective filters. These findings help narrow the gap between perception and known neurophysiological effects, and further our understanding of how attention improves contrast sensitivity.
Meeting abstract presented at VSS 2014
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