Abstract
In 1949, G. R. GRICE performed an experiment to compare the processes of simultaneous and successive discrimination learning. He found that there were no differences between these two processes, and concluded that the two were essentially the same. These results were considered as supporting the stimulus-response theory of discrimination learning. But it is well known, in the “continuity-non-continuity controversy” in the discrimination learning, that variables such as type of apparatus, nature of the stimulus and general experimental procedures will have considerable influences upon the results. In the present experiment, the author intended to test whether or not the same results would be obtained under conditions which were different from the GRICE's experiment.
Seven female albino rats were trained in the jumping-stand apparatus. They were divided in two groups, four animals in one and three in the other. Two white circles which were 5.0cm.and 6.2cm. in diameter were used as stimuli. Half of each group was trained to the larger circle and the other half to the smaller. For group I (simultaneous discrimination), the percentage of correct responses was used as a measure of performance. In accordance with GRICE, the reaction latency was used with group II (successive discrimination) in order to determine the percentage of correct responses. Training, was continued until a criterion of 90% correct responses was reached. The learning situation was switched for the groups.
The results obtained were as follows ;
(1) Since the rats of group II were superior in both trials and errors to the rats of group I, so that their learning curves were not identical, the two learning processes could hardly be regarded as the same.
(2) In simultaneous discrimination learning, two types of solution were evidenced ; gradual and sudden.
(3) Since the difference between response latencies of the animals to the positive and negative stimulus was very small, GRICE's use of median latency as a method of measuring correct responses in successive discrimination problem is of doubtful value.
(4) Although there was incomplete transfer between simultaneous and successive discrimination when the learning situations were switched for the groups, relearning occured quite readily.
From the above results, it wa considered that although some common elements might be present in simultaneous and successive discrimination learning, they presented quite different situations for the subjects. Consequently, it seems premature for GRICE to regard these situations as identical and to cite them as evidence for support of a S-R theory of discrimination learning.
