Effects of extraneous stimulation on afterimage adaptation

Projected afterimages (AI) were measured serially with respect to size, intensity, and color. It was predicted that an acoustic signal administered before completion of the adaptive AI process would cause (1) disruption of ongoing trends, (2) regression to initial trends, (3) prolongation of the adaptive process, and (4) at least some defensive reactions. These predictions were substantiated in a group of 28 subjects compared with a control group of 28. In a second experiment where the signal was administered late in the AI series, only few effects were observed.