Canceling a Hue of a Negative Afterimage in Solid and Perceptually-Filled Color Images
33.3018, Sunday, 17-May, 8:30 am - 12:30 pm, Banyan Breezeway
Gennady Livitz1, Guillaume Riesen1, Ennio Mingolla1, Rhea Eskew2; 1Computational Vision Lab, Department of Communication Sciences and Disorders, Bouvé College of Health Sciences, Northeastern University, 2Psychology Department, Northeastern University
A negative afterimage is perceived as having a color “opposite” to those of the adapting stimulus. We investigated the effects of afterimages on the perception of color stimuli, as well as their effects on spatial chromatic induction. Anstis et al. ( 1976) showed that the effects of direct light stimulation could be integrated with the chromatic perception resulting from temporal (color adaptation) and spatial color contrast. This could be an additive interaction, meaning that a negative afterimage could be canceled either by light of the same chromaticity or by a complementary surround. In a series of hue cancellation experiments, observers judged the chromatic neutrality of a test after adapting to a colored image. In the experiments with direct light stimulation, observers were instructed to change the saturation of the test stimulus, which had the same hue as the adapting light, until the test figure appeared chromatically neutral. The spatial contrast procedure was similar except that observers adjusted the surround of the test stimulus to cancel the afterimage using spatial chromatic induction; in this case, the surround hue was complementary to the adapting stimulus. Results show that afterimages are either not complementary, do not mix additively with color stimuli, or both. For many of the adapting colors, the hue of the subsequent test did not appear neutral at the observer’s settings; observers were able to reduce the saturation of the test but not make it look grey. This non-complementarity was most pronounced in the afterimage of a blue stimulus. However in afterimages caused by perceptually-filled (neon color) stimuli, the interactions were more like additive mixing and the final percept came closer to chromatic neutrality. This difference may be related to the tendency of afterimages to be perceived as filters over solid stimuli while additively mixing with perceptually-filled surfaces from neon stimuli.