Retention of Simple Motor Skills as a Function of the Number of Trials by Which KR is Delayed

I. Bilodeau (1956) studied the effect of delay of knowledge of results (KR) in a siruation in which additional responses were required during the delay, e.g., in the 2-trial delay condition KR on the first trial was given after the third trial had been completed, KR on the second trial after the fourth, etc. She found that with I-, 2-, 3-, or 5-trial delays rate of learning and level of accuracy reached within 30 KR trials decrease with the number of trials by which KR is delayed. . One purpose of the present experiment was to determine whether these findings hold for other simple skills. Confirmation of the Bilodeau finding would have special interest since the only other Es (Lorge & Thorndike, 1935) to use such a delay technique failed to find any learning, although only one trial intervened. A second purpose was to investigate the effect of the trial-delay method on the retention of such skills. A previous study (Lavery, 1962) suggested that any method which enhances the cues inherent in the [ask produces higher retention than one chat does not. It could be supposed that the trial-delay method obliges Ss to compare responses just made with responses made some trials back and thus they have more opportunity of profiting from such cues. It was predicted, therefore, that Ss trained with delay of KR would retain a skill better than Ss who received immediate KR. Two experiments were carried out. The first dealt with the problem of extending the trial-delay technique to orher tasks and of measuring its effecc on retention. The second experiment was designed to measure the effect upon retention of longer and shorter training periods within each technique.