During the preparation of a saccadic eye movement, a visual stimulus is more efficiently processed when it is spatially coincident with the saccadic target as compared to when the visual and the saccadic targets are displayed at different locations. We studied the coupling between visual selective attention and saccadic preparation by measuring orientation acuity of human subjects at different locations relative to the saccadic target and at different delays relative to the saccade cue onset. First, we generalized previous results (E. Castet, S. Jeanjean, A. Montagnini, D. Laugier, & G. S. Masson, 2006) revealing that a dramatic perceptual advantage at the saccadic target emerges dynamically within the first 150-200 ms from saccade cue onset. Second, by varying the validity of the spatial cue for the discrimination task, we encouraged subjects to modulate the spatial distribution of attentional resources independently from the automatic deployment to saccadic target. We found that an independent component of attention can be voluntarily deployed away from the saccadic target. The relative weight of the automatic versus the independent component of attention increases across time during saccadic preparation.

During rapid eye movements, motion of the stationary world is generally not perceived despite displacement of the whole image on the retina. Here we report that during saccades, human observers sensed visual motion of patterns with low spatial frequency. The effect was greatest when the stimulus was spatiotemporally optimal for motion detection by the magnocellular pathway. Adaptation experiments demonstrated dependence of this intrasaccadic motion percept on activation of direction-selective mechanisms. Even two-dimensional complex motion percepts requiring spatial integration of early motion signals were observed during saccades. These results indicate that the magnocellular pathway functions during saccades, and that only spatiotemporal limitations of visual motion perception are important in suppressing awareness of intrasaccadic motion signals.

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