MODIFICATION OF RATS' VISUAL CLIFF BEHAVIOR BY VISUAL EXPERIENCE

Abstract

A great deal of research has been carried out to test the effect of experience on the performances of various mammalian species in the visual cliff apparatus (cf. 8). It was found in previous studies that dark-reared rats avoided the optically deep side of a visual cliff as accurately as their light reared counterparts (8, 9). On the bases of these result it was concluded that visually inexperienced rats could discriminate depth. On the other hand, since the original reports of the visual cliff behavior by GIBSON and her colleagues, many researchers have performed the experiments that showed effects of visual experience. Furthermore it is said that visual cliff behavior varies according to the pattern presented in the visual cliff (2, 5, 6). The purpose of the present experiment was to investigate the effects of rearing environment on visual cliff behavior when they were tested after some period of visually controlled rearing by using different kinds of patterns. In Exp. I the effect of deprivation of visual experience was tested by the dark vs light rearing method. In Exp. II the effect of specific visual experience was tested by the deep vs shallow rearing. In Exp. III & IV the effect of familiarity to the pattern presented in a visual cliff situation was tested.
In 4 experiments the effect of visual experience on rats' visual cliff behavior was tested. In Exp. I the effect of deprivation of visual experience was tested. Light reared rats showed preference for the shallow side and for a pattern whose element size was 11 degrees in retinal angle. But dark reared rats didn't show any preference in the visual cliff tests. In Exp. II to IV the effects of shallow vs. deep rearing and the effects of exposure to the specific pattern used in the rearing situation were tested. In Exp. II & III the data of the 1st trial only showed that the shallow reared rats showed a preference for the shallow side and the deep reared rats showed no preference. But in Exp. IV there was no difference between shallow reared and deep reared rats even in the 1st trial. And in Exp. III & IV, if the data of the 1st trial were combined with those of the 2nd trial, rats showed a preference for the shallow side when they were familiar with the pattern used in the visual cliff. But they showed no preference when they were unfamiliar with the pattern used in the visual cliff. But the difference between the patterns used didn't reach a significant level.