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.

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Rats typically have great difficulty acquiring a discriminated operant bar avoidance. But, the majority of animals learn to bar-press to terminate shock (escape response). The problem of generating efficient bar-press behavior in a relatively convenient period of time and in a satisfactorily high percentage of subjects has been a problem for experimenters working with the Sidman avoidance reinforcement schedule. In a recent review of the literature, it is concluded that the rats fail to master the bar-press conditioned operant response because it is so unlike any of the animal's naturally occurring “species-specific defense reactions (SSDRs)”.
The present study asked whether an appetitive pretraining procedure designed to produce high levels of avoidance reponding early in training could have sustained beneficial effects on the performance of a discriminated flapper-push avoidance task. If a flapper-pushing response was positively reinforced and established before the avoidance test, it seems logical that the subsequent avoidance acquisition task would be facilitated.
During an 8-day pretraining period 16 animals (Experimental) were trained to push a flapper for food reward. Eight animals (Control) received the same number of food pellets and were exposed to the same apparatus as the Experimental animals. However, the manipulandum was inoperative during pretraining for Control animals. On completion of the appetitive pretraining period, all animals received the signaled Sidman avoidance conditioning treatment (a daily 1 hr. conditioning session for 6 consecutive days). For example, if the animal permitted 30 sec. to elapse without a flapper-push, a warning stimulus (1250 Hz., 84 db. tone, 5 sec. duration) appeared and remained until terminated by a response. Each response in the absence of tone postponed both tone and a brief shock (shock-shock interval 3 sec., shock duration 0.4 sec., shock intensity 1 ma. a. c.) for 30 sec.
Fig. 1 shows the number of flapper-push responses during the appetitive pretraining period for both Experimental and Control groups. The Experimental group made more responses as compared to the Control group. The present data show that appetitive pretraining to flapper-push for food improves the later acquisition of flapper-push avoidance (Fig. 2 and 4). It is likely that the Experimental group was responding for food during avoidance sessions, although these animals did not receive food reinforcement for response emitted. The significant differences in the number of interstimulus responses (Fig. 3) and total flapperpushing response (Fig. 4) between the Experimental and Control groups indicate that the appetitive pretraining procedure generates a high response rate. Figs. 2 and 5 indicates that the Control group performed quite poorly during the first three avoidance conditioning days. It is conceivable that the repeated shocks during these initial conditioning days firmly establish SSDRs in the Control subjects.
The greater frequency of avoidance responses in the Experimental group was associated with a greater frequency of non-warning flapper responses, indicating that improved avoidance was a direct result of a general increase in flapperpushing. Therefore, increasing the habit strength by pretraining for food, which should not interference with the fear conditioning, seems to be critical.

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[in Japanese]

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