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Maria Pereverzeva, Paola Binda, Scott O. Murray; Covert attention to bright and dark surfaces drives pupillary responses. Journal of Vision 2012;12(9):661. doi: 10.1167/12.9.661.
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Changes in pupil size are most often attributed to changes in light levels – an increase in ambient light results in constriction and a decrease results in dilation. However, a variety of perceptual, cognitive and motivational factors have been shown to influence pupil size suggesting complex feedback circuits from higher-order brain structures. This circuitry raises the possibility that the behavioral relevance of a particular light level in an image could affect pupil size. Specifically, we addressed whether – while keeping eye position fixed – attending to a brighter or darker part of an image results in pupillary constriction and dilation, respectively.
Test displays consisted of one bright and one dark disk presented on the left and right side of a uniform gray background. A trial consisted of cueing to which side (left or right) to shift attention, followed by a brief interval, and then the presentation of the two disks. Attention direction and spatial position of the bright and dark disks were counterbalanced across trials. To ensure task engagement, subjects were asked to count, and respond with a button press at the end of the trial, the number of brief changes in chromaticity of a small colored dot located in the center of the attended disk while ignoring color changes in the dot located in the unattended disk. We found that attending to the bright and dark disks produced reliable pupil constrictions and dilations, respectively. Since, under natural viewing conditions a shift of attention is usually followed by an eye movement in the same direction, our data suggest that the visual system – even at the level of the pupil – anticipates and adjusts to future light level conditions.
Meeting abstract presented at VSS 2012
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