An analysis of aftereffects in the measurement of the correction effect

Ss, under prismatic viewing, aligned a spot of light to the apparent straightahead first in the dark and then under illumination. Ss made these judgments either by controlling the spot themselves or by directing E in moving it. For both types of alignment procedures, judgments were significantly more veridical in the illuminated room (correction effect). Aftereffects, measured after both the spot alignment in the dark and in the light, were found to be significant only when S moved the stimulus. These results contradict the argument that the egocentric localization processes involved in the production of the correction effect itself are the basis of the aftereffects obtained.