The Neurophysiological Basis for the Importance of Borders in Human Color Perception

Undergraduate #91
Discipline: Social, Behavioral, and Economic Sciences
Subcategory: Social Sciences/Psychology/Economics

Vera Pertsovskaya - Hunter College
Co-Author(s): Valerie Nunez, Hunter College, NY,NY; James Gordon, Hunter College, NY,NY

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From an evolutionary perspective, color vision was a necessary development in the evolution of life as it allowed organisms to be capable of recognizing critical objects within their environments. The way that the color of an object is perceived is strongly dependent on the color difference at the border of the object (Krauskopf, 1963). Recent research (Xing et al., 2015) has demonstrated that the effect of brightness contrast is happening mainly at the edges of objects. However, the cortical mechanisms of color vision are not yet clear. In this study, we examined the neural mechanisms underlying human color perception. Multi-channeled chromatic visual evoked potentials (cVEPs) were recorded in response to colored stimuli for a range of saturations to observe the human cortical response to color patterns. We examined the responses to a patterned (checkerboard) stimulus and a non-patterned, full-field, chromatic stimulus. The outer edges for all stimuli were blurred. The responses were the largest over the primary visual cortex. The cVEP data was indicative of the existence of non-linear mechanisms over the range of the stimulus saturations that was used. We were able to determine that whereas the latency for the non-patterned stimulus did not shift, the latency for the patterned stimulus decreased with an increase in the chromaticity of the stimulus. For both types of stimuli, the peak magnitude increased with an increase in the chromaticity. However, even though the patterned stimulus had half of the amount of total color, it displayed a significantly greater peak response. This demonstrates the significance of borders in the physiological mechanisms underlying human color perception. Our future research will focus on delineating more thoroughly the relationship between sensation and psychophysiology; We will strive to further understand the locus of the cortical non-linearity. References: Gordon, James, and Robert Shapley. “Brightness Contrast Inhibits Color Induction: Evidence for a New Kind of Color Theory.” Spatial Vision 19.2 (2006): 133-46. Web. Kirschmann A. “Ueber die quantitativen Verha¨ltnisse des simultanen Helligkeits- und Farben-contrastes.” Philosophische Studien 6 (1891):417–491. Web. Krauskopf, John. “A Color-Mixer with Monochromatic Primaries.” The American Journal of Psychology 76.3 (1963): 496. Web. Xing, Dajun, Ahmed Ouni, Stephanie Chen, Hinde Sahmoud, James Gordon, and Robert Shapley. “Brightness-Color Interactions in Human Early Visual Cortex.” Journal of Neuroscience 35.5 (2015): 2226-232. Web.

Funder Acknowledgement(s): We would like to thank Afsana Amir, Chloe Brittenham, Norine Chan, Syed Ali Hassan, and Carim-Sanni Ridwan for their contributions to this work. We also like to acknowledge the John P. McNulty Scholars Program for their support in this research study.

Faculty Advisor: James Gordon, jgordon@hunter.cuny.edu

Role: I assisted in the recording of the multi-channeled chromatic visual evoked potentials