Undergraduate students at two universities, designated as Groups A and B, participated in this study. The Mean scores on a visual memory span test and a visual working memory test of Group A were significantly higher than those in Group B. Participants individually watched a CRT display showing two cars that were moving in the same direction on two parallel tracks for various durations and distances. They were asked to identify the car that had traveled for the longer duration and to explain the reasons for their decision. Then, they completed an instructional booklet that taught about planning to make judgments of duration for movement. Finally, they did the duration judgment tasks for the car's movements again. The following are the main results. (a) The number of undergraduates who answered correctly increased after their learning experience. (b) The rates of correct responses were significantly related to the memory test scores. Furthermore, the data suggested that larger memory capacity could compensate for poorer planning. (c) The two groups differed in strategies for the duration judgment tasks.