Abstract
Chronometric studies provide strong support that mental imagery recruits perceptual processes (Shepard & Metzler, 1970; Shepard & Cooper, 1971). Further, there is recent evidence that information on effort is important in perceptual coding (Proffitt, 2003). If imagery recruits perceptual processes and perception is influenced by anticipated effort, then imagery should be affected by anticipated effort. In two experiments, participants imagined self-rotation between two landmarks separated by 90 or 180 deg. In a near condition the landmarks were 2m away, while in a far condition they were 90m away. Imagined rotation between distant objects required significantly more time (175msec more for 90 deg rotations), even though the imagined self-motion was identical in both conditions. While the instructions were for self-rotation only, the result indicates that participants took the path from one landmark to the other into account without being aware that they did so. In a second experiment participants wore an 8kg backpack under the same conditions, with no change in instructions. Rotation times were 126msec longer and the near/far difference was 165msec. Of the tests of individual differences in field-dependence, sex, and handedness, only sex produced a significant difference (p<.02). The results suggest that spatial metrics, attended path, and anticipated effort all play a role in coding of mental imagery, but further research is required to ascertain whether the effects on anticipated effort are due to sensorimotor processes or semantically based tacit knowledge.