Showing papers in "Journal of Comparative and Physiological Psychology in 1965"

Rat's anticipation of diurnal and a-diurnal feeding.

Abstract: Rats, confined either to Skinner boxes or to activity wheels, were fed at regularly scheduled feeding times which were either diurnal, i.e., every 24 hr., or a-diurnal, i.e., every 19 or 29 hr. Even though the a-diurnal Ss had been born, reared, and tested under 19or 29-hr, schedules to provide further support for the anticipation of feeding, they failed to show such an effect. The fact that the diurnal Ss showed both increased running and increased bar pressing in the hours just before feeding indicates that when such an anticipation occurs, it is governed by a 24-hr, biological clock rather than being based upon deprivation produced stimuli.

Latent inhibition: effects of frequency of nonreinforced preexposure of the CS.

Abstract: It has been found that nonreinforeed preexposure to the to-be-conditioned stimulus results in a decrement in performance during the acquisition phase of a classical defensive leg response conditioning procedure. The present study shows that: (a) this decrement is a function of the frequency of preexposure, (b) the size of the decrement remains constant over 4 days of acquisition training, and (c) the decrement as a function of preexposure is not significant during extinction. In a previous experiment Lubow and Moore (1959) demonstrated a phenomenon which they labeled latent inhibition. This term describes the decrement in conditioning performance 'which results from the nonreinforeed preexposure of the to-be-conditioned stimulus. The purpose of the following study was to extend the earlier findings. In that study, experimental and control observations were made from the same &. That is, S was preexposed for 10 trials to either a flashing light or a moving rotor; following this, S was conditioned on alternate trials to the light and to the rotor. Reinforced acquisition training was started immediately after the preexposure trials, and continued until a predetermined criterion of 10 CRs was reached in that session. In the present study we were interested in the effect of frequency of nonreinforeed preexposure of the to-be-conditioned stimulus on acquisition and extinction performance; and in the duration of latent inhibition, both within an acquisition session and between sessions. Finally, we were interested in demonstrating the latent inhibition phenomenon within the context of a different experimental design in which different Ss were used for different groups.