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Stephen Heinen, Elena Potapchuk, Scott Watamaniuk; Foveal attention augments catch-up saccade frequency during smooth pursuit. Journal of Vision 2015;15(12):1023. doi: 10.1167/15.12.1023.
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Previously, we showed that foveal stimuli increase catch-up saccade frequency during smooth pursuit, presumably because a salient foveal spot activates a position correction mechanism (Heinen et al., VSS 2013). However, since saccades are linked to attention (Corbetta et al., 1998), attention may be needed to activate position correction during pursuit. To investigate this, we moved attention in and out of the fovea while observers pursued a stimulus composed of 4 peripheral dots arranged symmetrically about a central one. At a random time, either the central dot or the 4 peripheral dots dimmed briefly to draw attention into or out of the fovea, and observers identified the dot with a keypress. Saccade frequency was highest when attention was drawn foveally, and reduced when it was drawn peripherally, supporting the idea that foveal attention during pursuit was modulating the saccadic mechanism. However, removing the central dot altogether further reduced saccades, indicating that the central spot attracted attention even when observers knew it was not a potential task target. It could be that attention that is focused in one location, rather than spread out over a greater area, can increase saccade frequency. To test whether focused attention could increase saccade frequency if it were directed to positions other than the fovea, we had observers perform the identification task on a miniature version of the 5-dot stimulus (.5 deg diameter) located either in the fovea or the periphery. Saccades were again reduced when the task was performed peripherally, indicating that focused attention specifically at the fovea engages the saccadic mechanism. The results suggest that attention modulates a position-correcting system used during pursuit, and are consistent with the idea that pursuit of foveal stimuli requires attention. Furthermore, attention may preferentially modulate structures in the pursuit pathway that are also active during foveating saccades.
Meeting abstract presented at VSS 2015
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