Abstract
Classic studies of mental imagery showed that the time required to mentally rotate a visual object depends on the amount of rotation, just like the physical rotation of a real object. The goal of our present study is to show that visual working memory serves as the buffer in which an object representation is held while the rotation occurs. We asked subjects to perform a mental rotation task during the delay interval of a change-detection task to determine whether mental rotation interferes with working memory storage and vice versa. The mental rotation task required subjects to determine whether a letter character—presented at 0, 72, or 144 degrees from upright—was presented in its canonical form or in a mirror-image form. In Experiment 1, this task was presented during the delay interval of a color change-detection task that was designed to selectively load visual object memory. The mental rotation and change-detection tasks were also presented individually as single-task control conditions. Compared to the single-task conditions, accuracy in both the change-detection and mental rotation tasks was impaired when both tasks were performed together, and the degree of impairment increased as the amount of rotation increased. Thus, it is difficult to mentally rotate a continuously visible object while simultaneously holding other objects in memory. In Experiment 2, a spatial change-detection task was used instead of a color change-detection task, and no systematic interference was observed between the rotation and memory tasks. Together, these results indicate that mental rotation requires the buffering of the to-be-rotated object in the object working memory subsystem, not in the spatial working memory subsystem.
This research was made possible by grant R01 MH63001 from the National Institute of Mental Health.