Augmented and Delayed Feedback in the Chevreul Pendulum Illusion.

Two experiments were performed with male and female college students to determine the effects of augmented and delayed feedback on the Chevreul pendulum effect: the tendency of a small pendulum, when suspended from the hand and imaginatively concentrated on, to oscillate seemingly of its own accord. Using a time exposure photographic measurement technique and an electronically monitored pendulum, visual and auditory analog feedback was presented to Ss during imaginal processing tasks. It was found in Experiment I (N = 14) that both visual and auditory analog feedback facilitated the pendulum effect, although not as extensively as normal visual feedback. In Experiment II (N = 30) it was found that delayed visual analog feedback disrupted performance with the pendulum but that delayed auditory analog feedback did not. The reliable within-Ss results established the pendulum effect as a skilled behavior which can be investigated like other sensory motor skills.