The purpose of the present study was as follows: 1. The first purpose was to investigate whether the superiority of performance level of partial reinforcement group to continuous reinforcement group was found in the part of goalbox area in linear runway. 2. The second purpose was to investigate the effect of the length of detention time in the goal box in nonreinf orced trials to the performance level. For the first purpose, the runway was divided into four parts (i.e., start box area, first runway area, second runway area, and goal box area), running time was measured in each part and 120 training trials which were more than that of any experiment, were used in the schedule of 10 trials per day for 12 training days. The four groups which were consisted of five or six subjects (albino rats) were used. One group was the continuous reinforcement group and the other three groups were the partial reinforcement (50%) groups. For the second purpose, the one of 3 lengths of the detention time (sec) in the goal box in the nonreinf orced trial (2.5sec, 10.5sec, 30sec) was assigned to each group of the partial reinforcement groups. Results were as follows: 1. The superiority of performance level of the partial reinforcement group to the continuous reinforcement group was detected in all parts of the runway, and therefore, so in the goal box area. This was not due to the number of performed training trials per second. But, when the relation between the period in which the superiority of the performance of the partial reinforcement group appeared and the part of the runway was analyzed, it was found that the relation was in accord with the relation proposed by Goodrich (1959). 2. Effect of the detention time was detected by the fact that Group 10.5 (the detention time, 10.5 sec) was equal to Group C (the continuous group) and inferior to Group 2.5 and Group 30 in the performance level. The above results could be explained by revising in part the propositions by Goodrich (1959) and Wagner (1961) to explain the superiority of the performance level reinforced in the partial reinforcement schedule.
The present experiment was designed to test a hypothesis that magnitude of the overtraining reversal effect (ORE) is positively related to number of stimulus dimensions in the discrimination problem. This hypothesis was deduced from attention theories in discrimination learning (Lovejoy, 1966; Mackintosh, 1965), which assume that discrimination learning involves the acquisition of mediating attention responses to the relevant dimension and selective responses to the positive stimulus. A 2×3 factorial design (i.e. 6 groups) was used, which incorporated degrees of original training (criterion and overtraining) and number of stimulus dimensions (1, 2, and 3). The Ss were 144 preschool children with a mean age of 5 years and 7 months, and they were assigned to one of the 6 groups equating in age and sex. Half of the Ss were trained on a 2-choice simultaneous discrimination problem to a criterion of 10 successive correct responses and the rest were given additional 50 overtraining trials after reaching the criterion. Immediately after completing the original discrimination, they were given a reversal discrimination to a criterion of 10 successive correct responses or 100 training trials. Throughout the experiment, S's responses were to point out one of the 2 stimuli on each card, and reinforcements were provided by E's saying “Hit” or “Miss”. The Ss were trained on one of the 3 discrimination problems: (1) one-dimensional problem consisting of color, form, or size dimension, (2) 2-dimensional problem consisting of color-form, form-size, or size-color dimensions, and (3) 3-dimensional problem consisting of color-form-size dimensions (Fig. 1). The positive stimulus and relevant dimension were counterbalanced within each problem. The main results were that (a) the original discrimination was more difficult with increasing the number of stimulus dimensions (Table 1), and (b) for the reversal discrimination, a significant interaction was obtained between the degree of training in originall discrimination and the number of stimulus dimensions (Table 2). This interaction indicated that (a) the magnitude of the ORE was positively related to the number of stimulus dimensions, and (b) the performance difference due to the number of dimensions was statistically significant when Ss were trained to reach the criterion in original discrimination, but there was no significant difference for the overtrained groups. The results supported the present hypothesis. The role of irrelevant dimensions in the ORE was emphasized in relation to the attention theory, and the relationship beween problem difficulty and the ORE was discussed.
During the all-night natural sleep, the activated sleeps (REM period) were confirmed by the polygraphic method in which the EEG, eye movements, pulse rate, respiration rate and the EMG of the sleeping subject were simultaneously recorded. The sleeper was awakened five minutes after an activated sleep pattern appeared and was made to introspect his dreaming. The following results were gained from investigations of the physiological and psychological changes observed in this period. 1) The mean of frequency of occurrence of activated sleeps in the all-night natural sleep was 3.8±1.4, and that of the total length was 84.8±40.9 minutes. Hence the rate of activated to all-night sleeps was 19.5±9.0%. 2) Sleeping subjects were awakened 5 minutes after the initial onset of activated sleeps and were made to recollect the contents of their dreams. Of 69 REM periods of the 10 subjects, 48 were dreaming (+) (69.6%), 14 were dreaming (-) (20.3%), and the rest were indistinguishable from mere thinking. 3) The changes in the EEG integration values that were obtained by the band pass filter type automatic frequency analyzer were not significantly different between dreaming (+) and dreaming (-). However, two types were found of the changes in REM periods: the one dominant in the slow band (1-7HZ) and the other in 8-9HZ. 4) The REM patterns in activated sleeps could be classified into 4 categories from the criteria of amplitude, interval and appearing modes of REM. 5) Upon examination of the relationship between the occurrence or non-occurrence of dreaming and the REM patterns, the appearance of the RD (the stair-type REM pattern) in dreaming (+) was significant at the 5% level, but there was no difference in respect to the hour of sleep or the electrode positions for the eye-movement recording. 6) The contents of dreaming were dominantly visual: acoustic and tactile imageries of dreaming were also reported from a few subjects.
Two groups of male albino rats were run 20 trials per day on a black-white discrimination, motivated by electric shock (Fig. 1) to a learning criterion of 18 correct responses within a day in which the last 10 responses must be correct. One group was injected with 2ml/kg of physiological saline and the other with 20mg/kg of chlordiazepoxide (CDP) (2ml/kg of a 10mg/ml solution) both intraperitoneally 30min prior to the first daily trial. Two days after reaching criterion, the rats were given reversal training to the same criterion or a maximum of 200 trials: half the animals in each group were changed in drug state and the rest were not changed, and thus 4 groups (SAL-SAL, SAL-CDP: CDP-SAL, CDP-CDP) were run as in acquisition except the stimulus incentives were reversed. Mean trials to criterion in acquisition and reversal are shown in Table 1 for each subgroup. Acquisition was slightly but significantly depressed by CDP (also see Fig. 2), while reversal learning was substantially retarded by the drug. So far as the trial variable was concerned, these was no significant interaction or no indication of it (and thus no drug-learning dissociation) between drugstates during acquisition and reversal. Fig. 3 shows per cent errors during reversal training: per cent errors on the first reversal day clearly indicated a dissociative effect: that is, the rats without drug-state change (SAL-SAL, CDP-CDP) made more errors than those with such change (SAL-CDP, CDP-SAL). In addition, those rats given drug during acquisition were better in performance than those which had been treated with saline. This finding may be at least partially explained by a negative correlation within each group between trials to criterion in acquisition and the number of errors on the first reversal day (Table 1). That is, response strength would be weaker when more trials were needed to the identical learning criterion. No significant effects of CDP upon running times were found either during acquisition or reversal except that the drug significantly retarded wrong-response speed on the first acquisition day (Table 2). A depressant effect of CDP upon discrimination learning was explained in terms of the drug's inhibitory action on negative incentives. It may be assumed that this effect was slight during acquisition but strong during reversal because the formerly-rewarded and thus strongly-reinforced response was punished in reversal and this yielded an approach-avoidance conflict: CDP attenuated the conflict and facilitated the approach response to the punished, negative stimulus. The dissociated performance found on the first reversal day may be explained in terms of generalization decrements since the internal stimulus was changed by shift in drug-state, but this dissociative effect was only transitory, being replaced by the drug's inhibitory effect on negative incentives. The drug's dissociative effect and the depressant effect upon negative incentives seemed to be mediated by different mechanisms. The latter psychotropic effect might be ascribed to the CDP's inhibitory action, direct or indirect, upon the hippocampus. Behavioral studies have shown that hippocampal lesions impair passive avoidance (which is essentially an approach-avoidance conflict), experimental extinction and discrimination reversal (Kimble, 1968). Electrophysiologically, CDP was found to inhibit a prolonged after-discharge, produced by electrical stimulation of the limbic system (Sternbach et al., 1964), as well as to increase seizure threshold of the hippocampus (Hara and Miyake, 1964). Our observation also suggested some and probably depressant effects of CDP upon the hippocampus. Both 10 and 40mg/kg, i. p. of CDP produced continuous rythmic activities of 20-30Hz in cortical and subcortical structures in the waking state. Theta waves, usually associated with gross body movements were not observed under CDP (Fig. 4). Slow-wave sleep was often replaced by high-amplitude