Effect of sensorimotor adaptation of saccades on covert attention.

Abstract

To interact with our environment, we continuously select visual information relevant to our goals. Visual selection is achieved via tightly inter-related overt eye-movements (saccades) and covert shifts of visuo-spatial attention. In face of perturbations, the saccadic system can adapt to maintain saccade accuracy. The possible consequences of the changes induced by saccadic adaptation on covert attention remain, however, unknown. To address this question, healthy participants (N=40) were separately submitted to one of four exposure phases: adaptation of leftward or rightward saccades ("adapt-left"/"adapt-right") or mere execution of leftward or rightward saccades ("control-left"/"control-right"). Reactive saccades were adaptively shortened, using the double-step target paradigm (McLaughlin 1967), where the target first stepped to 11° and then stepped backward to 7° during saccade. Covert attention was tested before and immediately after each exposure phase, by asking subjects to detect a visual target flashed at a random location to the right or left (±3°, ±7°, ±11°, ±15°) of a central fixation point, and to answer by button press while maintaining fixation. Results indicated that in both "adapt" groups, and as classically reported, the gain of saccades performed in the adapted direction decreased significantly (-15% on average), without any change of saccades in the non-adapted direction. In the adapt-left group, reaction times to left-sided targets decreased significantly (mean change= -7.5%), regardless of target eccentricity. No change in detection performance was observed in either control group. Surprisingly, no change in reaction time was found in the adapt-right group. In conclusion, covert spatial attention appears to be deployed more efficiently in the adapted hemi-field, but only when saccadic adaptation was induced in the left hemi-field. On-going experiments will test whether this asymmetrical coupling between adaptation and attention is a general feature applying to other types of adaptation (lengthening versus shortening of amplitude) and types of saccades (voluntary versus reactive). Meeting abstract presented at VSS 2013