Less attention is more in the preparation of antisaccades, but not prosaccades.
To make a saccadic eye movement to a target we must first attend to it. It is therefore not surprising that diverting attention increases saccade latency, but is latency increased in all cases? We show that attending to a peripheral discrimination task has a paradoxical effect. If the stimulus to be attended appears shortly (100 to 300 ms) before an eye movement is made in a direction opposite to that of a presented stimulus (an antisaccade), its latency is reduced to well below baseline performance. In contrast, latencies for saccades toward the stimulus (prosaccades) are increased under similar conditions. This paradoxical effect may arise from competition between the processes mediating prosaccades and antisaccades. When the discrimination task is presented at the critical moment, it interferes with a reflexive prosaccade, allowing faster antisaccades. The results suggest that the suppression of sensorimotor reflexes can facilitate volitional motor acts.
Kristjánsson
A
A
Vision Sciences Laboratory, Harvard University, 33 Kirkland Street, Cambridge, Massachusetts 02138, USA. kristjan@wjh.harvard.edu
Chen
Y
Y
Nakayama
K
K
D001288:Attention / Q000502:physiology*; D005556:Form Perception; D006801:Humans; D008027:Light; D010775:Photic Stimulation; D012438:Saccades / Q000502:physiology*; D013997:Time Factors