Properties of perception of laterally moving objects in persons with profound retardation

ABSTRACT. Twenty-two persons with profound retardation were assessed for their perception of moving objects at a velocity of 5 s^-1. Abnormalities were not found in the ocular structures and optic discs of subjects upon ophthalmological examination. Stimuli consisted of six habituation trials and two test trials. Duration of eye movement in pursuit of stimulus was estimated by calculating the linearity and gradients of electro-oculograms. Subjects were divided into three groups based on the change of estimated time of pursuit eye movement. Those showing habituation as well as dishabituation (group 1) had higher developmental communicative ages than subjects with only habituation (group 2) and subjects who did not exhibit habituation (group 3). The results indicated a relationship between the perception of moving objects and the development of communication level in persons with profound retardation. The present study investigated abnormalities in the computer tomographic scanning of the subjects' heads and found cerebral disturbance of the visual cognition of moving objects in persons with profound retardation.