A rotation aftereffect changes both the speed and the preferred direction of mental rotation

Three experiments are reported that replicate and extend the finding of M. C. Corballis and R. McLaren (1982) regarding the interaction between mental rotation and the rotation aftereffect. In Experiment 1, participants saw tilted characters and made the usual parity judgment. In Experiment 2, participants were explicitly instructed to rotate the characters mentally into one direction or the other. In Experiment 3, participants had to report the direction into which they had mentally. rotated. In all experiments, the function relating RT to the rotational angle was influenced by the aftereffect. RT was accelerated if the mental rotation was congruent with the aftereffect and decelerated if it was incongruent. A strategic change of direction of the mental rotation accounted only for some portion of this effect. The major portion has to be attributed to a direct interaction of two movements. The data suggest that the speed of the aftereffect combines with the speed of the mental rotation and, therefore, that imagery and perception share 1 representational medium.