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John Palmer, Cathleen M. Moore; Using foils to measure spatial tuning functions for visual attention. Journal of Vision 2007;7(9):956. doi: 10.1167/7.9.956.
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© ARVO (1962-2015); The Authors (2016-present)
Our goal is to measure the spatial extent of visual attention using a psychophysical method that can be compared across behavior and physiology. To do so, we employ a selective attention task in which observers try to detect a visual target while ignoring a nearby foil that is identical to the target except for location. We vary both the contrast of the foil and the separation between the foil and the relevant location. The appropriate way to quantify spatial selectivity in this task depends on how attention modulates the effect of contrast. Two of the most common hypotheses for attentional modulation are contrast gain versus an all-or-none mixture. In contrast gain, the effect of the foil is attenuated by scaling its effective contrast; in all-or-none mixtures, the effect of the foil is completely blocked on some trials but not others. Contrary to prior studies that have been consistent with contrast gain, our results clearly disconfirm the predictions of the contrast gain hypothesis. Instead, the results are consistent with the all-or-none hypothesis. One possible reason for this discrepancy is a difference in the task. In most prior studies, the relevance of different locations was varied in a divided attention task; in this study, the foil was completely irrelevant in a selective attention task. We are now using this selective attention task to measure the spatial tuning function of visual attention.
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