Perceptual aftereffects of sustained convergence

Fixating a target for 6 or 8 min was shown to produce distance aftereffects that varied in direction (i.e., over- or underestimation) and magnitude as a linear function of the reciprocal of the observation distance. Changing fixation during the inducing period also was effective. These aftereffects provide a logical alternative to the assumption of recalibration and serve to challenge the claim of visual change as a result of prism adaptation.