INTRODUCTION TO PSYCHOLOGY-PSY 100

Color Vision

sensitive to different wavelengths; long, medium, and short wavelengths. The theory makes us understand that the major colors which are sensitive to cone are red, green, and blue but they are not the only color that strikes the retina. Yellow light also strikes the retina and during the process, it stimulates the red-sensitive and green-sensitive cones. Purple light also strikes the retina and it evokes strong reactions from both red-sensitive and blue-sensitive cones. We learned that Trichromatic Theory helps us understand color blindness and in this case red–green color blindness. This is a type of color blindness where people cannot differentiate between red and green because they have normal blue-sensitive cones. The trichromatic theory fails to present all aspects of color vision and thus fails to explain the afterimage phenomenon (Hockenbury & Sandra 99).

On the other side, the opponent-process theory of color vision presents four basic colors which oppose each other. These colors come in the form of two pairs of color-sensitive neurons; blue–yellow and red-green. The theory argues that if red is stimulated, green is inhibited and if green is stimulated, red is inhibited. Meaning that green and red cannot both be stimulated simultaneously. The same happens to blue–yellow pair. Other colors involved in this theory include purple which stimulates the red from the red–green pair. It also stimulates the blue of the blue–yellow pair. Another color is orange which activates red in the red–green pair and yellow in the blue–yellow pair. Unlike the trichromatic theory, afterimages can be explained in the opponent-process theory through the process of sensory adaptation. The opponent-process theory helps us to understand how white light has wavelengths for all colors. Both theories describe the process of color vision at different stages of visual processing and it makes me believe they are correct. The trichromatic theory touched on how cones of the retina respond to and encode different colors. The opponent-process theory touched on how ganglion cells respond to and encode different colors (Hockenbury & Sandra 99-100).

Works Cited

Hockenbury, Don H., and Sandra E. Hockenbury. Discovering psychology. Six Edition Macmillan, 2014