ABSTRACT
In each of two studies, subjects were exposed to a continuously changing prismatic displacement with a mean value of 19 prism diopters (“variable displacement”) and to a fixed 19-diopter displacement (“fixed displacement”). In Experiment 1, we found significant adaptation (post-pre shifts in hand-eye coordination) for fixed, but not for variable, displacement. Experiment 2 demonstrated that adaptation can be obtained for variable displacement, but that it is very fragile and will be lost if the measures of adaptation are preceded by even a very brief exposure of the hand to normal or nearnormal vision. Contrary to the results of some previous studies, we did not observe an increase in within-S dispersion of target-pointing responses as a result of exposure to variable displacement.
