Robust repulsion in perceived motion direction induced by visual working memory despite the demand characteristics

Motion repulsion is a visual illusion in which perception of moving dots is shifted away from its actual direction with the presence of another field of dots moving in a different direction. Kang et al. (2011) have demonstrated that the motion repulsion also occurs for the perceived field of dots when subjects hold another field of moving dots in working memory. Here, it was tested whether the perceptual shift induced by working memory is resistant to the demand characteristics, subjects’ tendency of conforming to the expected hypothesis of the experimenter. Subjects were tested over two separate days. On the first day of participation, they were presented with a sequence of two random-dot motion displays and performed a perceptual judgment task for the second motion display while holding the first display in their working memory. On the second day of participation, the same experiment was run; but the subjects were informed that their performance was inaccurate (inaccuracy instruction group) or judgments were shifted away from the direction of the other motion stimulus (repulsion instruction group). Despite these instructions, perceptual repulsion was robustly reproduced. This result indicates that our visual working memory representation robustly alters perception, providing converging evidence for a close relation between working memory and perception.