Conditioning to avoid milk or a compartment by the midbrain central grey stimulation for cats, who displayed the escape behavior or the “fear-like behavior” by the stimulation was tried. The procedure of the conditioning was the same as that employed in NAKAO (13).
Each of four cats was given milk from a dish in a observation box for five minutes after 24 hours food deprivation. Total duration of drinking was measured. One week after the control observation, the cat was again given milk from the dish in the observation box for five minutes after 24 hours food deprivation. But in this time the cat received the midbrain central grey stimulation during one second at any time when he was just going to drink.
The procedure for conditioning of the compartment avoidance behavior was as follows. As one trial, each of six cats, including the four cats above mentioned, received five times the five seconds midbrain central grey stimulation for three minutes in one of two compartments with white and black walls respectively, then he was put in the other compartment for three minutes without the stimulation. The cats had the conditioning trials five times a day. During the conditioning trials there was a barrier between the two compartments so that the cats could not go through from one compartment to the other. After the five conditioning trials each cat was put in the conditioned compartment where the cat had received the stimulation, in order to observe whether he leaped to the other compartment where he had received no stimulation. The cat had the five test trials in a day. If he had leaped to the other compartment in the test trials, he was given only the five test trials in the next day. Then if he showed again the avoidance from the conditioned compartment, it was considered that the avoidance conditioning was performed. If the cat showed no leaping to the other compartment in the test trials, he was given the five conditioning trials and the five test trials in the next day. When even after the training for ten days he showed no leaping to the other compartment, his experiment was ended.
Results were following :
1. Every four cats could be conditioned to avoid milk and keep away from the milk dish (see. Fig. 2).
2. Three of the six cats learned to avoid the conditioned compartment (No. 1, No. 4 and No. 5). Two cats showed the avoidance behavior only a little (No. 2 and No. 6). One cat completely failed to show the avoidance behavior (No. 3) (see Fig. 3).
From these findings, it was suggested that the midbrain central gray stimulation was served as the noxious stimulus.

View full abstract

The purpose of the present study was to investigate the effect of partial reinforcement during training period on latent extinction.
All Ss were maintained on a 23-hr. hunger deprivation schedule and given four training trials a day in the black straight runway for ten days. On all trials the Ss were detained in the goal box for 30 seconds. A 5-min. intertrial interval was used.
Group E4 and C4 were reinforced with grains of rice on all trials.
Group E3 and C3 were randomly reinforced on three-fourths of every day's trials.
Group E2 and C2 were randomly reinforced on a half of trials.
Group E1 and C1 were randomly reinforced on one-fourth of trials.
On Day 18, Ss in each experimental group (E4, E3, E2, E1) were given one 90-sec. non-reinforced placement into the goal box. Ss in control group (C4, C3, C2, C1) were given one 90-sec. placement into a neutral box which differed from the goal box in color and shape.
5 min. following the placement each S was given the first ordinary response extinction trial, and then given 9 more extinction trials with a 5-min. intertrial interval.
The results were as follows :
(1) Group E4 showed the the latent extinction effect in comparison to group C4.
(2) The effectiveness of latent extinction D. P. Was reduced, if Ss had been trained under partial reinforcement conditions.
(3) The facilitating effect of latent extinction on extinction trials was obtained. The frustration which could be generated by D. P. into the goal box was considered in relation to this facilitating effect.

View full abstract