Abstract
Background: Attention improves the visual system’s spatial resolution and distorts the perception of visual space: Perceived locations are repulsed away from the attentional focus (Suzuki & Cavanagh, 1997). However, little is known about whether and how attention affects visual space in action.
Methods: Here, we tested the effects of exogenous attention on visually guided reach movements. Attention was drawn involuntarily to a transient, uninformative cue (white square, 72ms) at one of two locations at 11.4º eccentricity and ±45º polar angle in either the upper left or upper right quadrant, respectively. After a brief delay (56ms), a reach target (green circle, 29ms) appeared at a randomly chosen position along an imaginary half-circle within the upper visual field with the same eccentricity as the cue positions. In the ‘attended’ condition, cue and target appeared within the same quadrant, whereas in the ‘unattended’ condition they appeared in opposite hemifields. For each target location, we calculated the distance between reach endpoint and target for the attended and the unattended condition.
Results & Conclusions: In the attended condition, reach endpoints toward targets in the vicinity of the attentional cue were repulsed away from the cue by up to ~0.9º, relative to the unattended condition. The spatial profile of the magnitude of this effect follows an ‘M’-shape centered on the focus of attention; i.e., the cue did not affect reaches toward targets at the cued location or far away from it. Reaction times (target onset to movement start) tended to be slower for targets near the cue, whereas movement times (movement start to landing time) at all locations tended to be faster in the attended than in the unattended condition. These results are consistent with an attentional distortion of visual space and suggest a parallelism between the perception and action systems for the representation of location.
Meeting abstract presented at VSS 2012