Mislocalization of a flash target on simple background in darkness

Subjects made voluntary saccades from the central fixation point to 5 deg in the right after the fixation point was turned off in darkness, while a continuously illuminated target was given at 5 deg in the left as a simple background target through a trial. A flash target was presented above the fixation point at the time near the saccade, and the subjects judged the distance between the background and flash targets perceptually. The results showed that the perceived distance between them reduced after the saccade onset. Furthermore, the background target was extinguished at the timing of the onset and peak velocity of the saccade. Their results were different from those of the continuously illuminated target. They were different from the results in earlier studies. The difference was explained by the visual masking effect during saccades and the afterimage of the background target.