Abstract
Li, Brenner, Cornelissen and Kim (2002) have recently reported that the perceived shape of spatiotemporally defined 2D object was systematically distorted during pursuit eye movement and that the perceived shape just reflected the retinal image. In most of the researches including Li et al, subjects did conjugate eye movement to track a pursuit dot moving in a 2D frontoparallel plane. In reality, however, an object usually moves in a 3D space, and observers have to do disconjugate eye movement to track it. When an observer pursues a pursuit dot moving away from an observer with his/her eyes, the two eyes rotate in opposite directions, and this may produce undesirable binocular disparities for the objects moving around the pursuit dot. To examine whether the visual system could compensate the undesirable binocular disparities with eye position information, we simulated a stereoscopic movie, which contained a spatiotemporally defined 2D rectangle in a frontoparallel plane and a pursuit dot moving towrard (or away from) observers. The rectangle was presented either to one eye (monocular condition) or both eyes (binocular condition), and a reference frame surrounding the target rectangle was present or absent. Monocular and binocular conditions were examined in separate sessions. Subjects saw the stimuli through a mirror type stereoscope and reported 2D shape in the monocular condition while they did slant of the target in the binocular condition. The perception of 3D slant as well as 2D shape of the target object was systematically distorted during disconjugate eye movement, and the perceptual distortion did not disappear even in the presence of the reference frame. These results imply that the visual system does not fully compensate the undesirable disparities caused by disconjugate eye movement and it may not use the reference information for the compensation.
This work was supported by Korea Research Foundation Grant (KRF-2003-042-H20004)