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Leah Bakst, Ilona Bloem, Joseph McGuire, Sam Ling; Dynamic spotlight model recovers the position but not the width of covert spatial attention. Journal of Vision 2020;20(11):327. doi: https://doi.org/10.1167/jov.20.11.327.
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© ARVO (1962-2015); The Authors (2016-present)
Covert attention has been shown to enhance both behavioral performance and corresponding visual signals in early visual cortices. Moreover, spatial uncertainty around the locus of attention appears to increase the width of the attentional field. However, we currently lack an efficient way to dynamically recover both the position and width of the attentional field from human brain data. In a series of tasks reliant on covert attention, observers were required to discriminate between letters and numbers embedded in a ring of dynamic noise. Observers were cued to attend to 1, 5, or 9 letters out of 20. To dynamically capture the position and width of the covert spotlight of attention, we fit a von Mises distribution to voxel BOLD responses in early visual cortex as a function of their receptive fields’ angular position, for each individual time point. In the first task, observers had to determine whether a digit appeared in place of one letter in the cued area of the ring. This dynamic spotlight model recovered the position of observers’ attentional fields at individual time points with high precision. However, no significant differences in the recovered width of the attentional field were associated with cued spatial uncertainty. In a second task, observers had to use spatial integration to determine whether there were more digits or letters in the cued area of the ring. The position of the attentional field was again recovered with high precision but, as before, there were no systematic differences in the width estimates. This suggests that covert attention enhances signaling in early visual cortex, but the manner in which spatial uncertainty interacts with this enhancement may not be as straightforward as previously thought.
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