PSYCO104 Lecture Notes - Lecture 8: Trichromacy, Additive Color, Visual Acuity

• School: University of Alberta
• Department: Psychology
• Course: PSYCO104
• Professor: Geoff Hollis

Document Summary

Rods are more sensitive to light than cones, and the different photoreceptors are sensitive to different wavelengths of light. There are also some who are "tetrachromates" who have a 4th cone in the orange. Rods only detect the presence of light, and are mono-chromatic. In bright light conditions, we generally primarily rely on cones for visual perception. In dark light conditions, rods do most of the visual "lifting", which are a bit more sensitive in the blue-green wavelength. Trichromatic color theory suggests that combined activation of different types of cones gives rise to the perception of non-primary colors. Trichromatic color theory is based on additive color measures that are able to create any color. Trichromatic color theory does not however explain certain visual phenomena, such as the colors found in an "after-image" formed after starting at a high contrast image for a duration, followed by looking at a plain background.