Presaccadic attention depends on eye movement direction

Abstract

AbstractWith every saccadic eye movement, humans bring new information into their fovea to be processed with high visual acuity. Notably, perception is enhanced already before a relevant item is foveated: During saccade preparation,presaccadic attentionshifts to the upcoming fixation location, which can be measured via behavioral correlates such as enhanced visual performance or modulations of sensory feature tuning. The coupling between saccadic eye movements and attention is assumed to be robust and mandatory, and considered a mechanism facilitating the integration of pre- and post-saccadic information. However, until recently it had not been investigated as a function of saccade direction. Here, we measured contrast response functions during fixation and saccade preparation and found that the pronounced response gain benefit typically elicited by presaccadic attention is selectively lacking before upward saccades – some observers even showed a cost. Individual observers’ sensitivity before upward saccades was negatively related to their amount of surface area in primary visual cortex representing the saccade target, suggesting a potential compensatory mechanism that optimizes the use of the limited neural resources processing the upper visual field. Our results raise the question how perceptual continuity is achieved and upward saccades can be accurately targeted despite the lack of – theoretically required – presaccadic attention.