Directional Asymmetry in the Duration of Simple Movement Aftereffects Produced by Movement Aftereffects Contingent on Colour

Movement aftereffects contingent on colour and pattern (CMAEs) were produced. A pattern, illuminated with red light and rotating clockwise, was alternated with its contrast-reversed ‘negative’, illuminated with green light and rotating counterclockwise. Subsequently, when the stationary patterns were presented, subjects reported counterclockwise MAEs on the ‘red’ pattern, and clockwise MAEs on the ‘green’ pattern. It was found that a simple MAE produced by adapting to the ‘red’ pattern and tested on the ‘green’ pattern was greater in duration when the direction of the inducing motion was opposite to that used in the CMAE adaptation procedure. It is suggested that this directional asymmetry in the duration of the simple MAE may be used as a within-subjects measure of the CMAE.