Autokinetic movement of an induced afterimage

Thirty-two female Ss participated in an experiment in which autokinetic movement (AKM) direction change frequency of an induced afterimage was assessed as a function of stimulus afterimage color (yellow or blue-green) and the presence or absence of eye strain. Afterimage color was found not to affect AKM frequency reports. However, eye strain significantly (p less than .002) affected such reports, with the fewest AKM direction changes reported when strain was present. These results were explained in terms of an error signal and noise analysis of AKM.