Abstract
Often optical devices cause distortions of the image perceived by humans affecting visual features in form and motion. In many cases, e.g. in progressive addition lenses, image skew is the prominent type of distortion. It is known that the human visual system adapts to skew distortion and shows form and motion aftereffects. In this study we investigate if motion direction aftereffects are also transferred to the other eye after monocular adaptation.
In a psychophysical experiment natural image sequences skew distorted into one direction were presented to subjects monocularly. After the adaptation phase, aftereffects were tested in a motion direction identification task. A random dot test stimulus moved coherently into one direction either diagonally upwards or downwards. Subjects had to answer with their perceived motion direction. This way perception was evaluated before and after adaptation for the adapted as well as the non-adapted eye. The distorted image sequence was presented to the adapted eye in between test trials for top-up adaptation.
The stimulus movement direction perceived as horizontal was estimated as through estimation of a psychometric function, separately for both eyes prior and after exposure to the skew adaptation stimulus. Results show a shift of motion angle perceived as horizontal for both eyes into the direction of the distortion of the adaptation stimulus.
In sum, after monocular exposure, aftereffects are transferred to the non-stimulated eye. Thus, skew adaptation can be assumed to occur at least partially in binocular areas.