PS102 Lecture Notes - Lecture 4: Process Theory, Visual System, Color Vision
Document Summary
Perceive small part of electromagnetic (em) spectrum. Light waves measured in nanometers (billionths of meter: from 400 nm to 700 nm. Hue is the specific colour perceived, wavelength how compact or wide the wave is. Brightness refers to the intensity of the light energy that is perceived, amplitude of wave the height. Saturation refers to the purity of the colour. Trichromatic theory (young-helmholtz: three types of colour receptors, cones most sensitive to blue/purple, green, red wavelengths, visual system combines activity from these cells, colours are perceived by additive mixture of impulses. If all are equally activated white colour is produced. Opponent-process theory (hering, 1870: three cone types, each responds to two different wavelengths-opposing pairs, red or green, blue or yellow, black or white. Explains afterimages: stare at certain colour, neural processes become fatigues, have rebound" effect with receptor responding with its opponent opposite reaction.
