PSY 252 Chapter 4: Psy 252 Chapter 4
Document Summary
Psychology 252 chapter 4: brightness and colour: vision depends on the presence of light. Illuminance is the amount of light falling on a surface. Luminance is the amount of light reflected from a surface: reflectance is the percentage of light falling on a surface, retinal illuminance is the amount of light reaching the retina, brightness corresponds to the illuminance and luminance. Retinal locus: astronomers would look slightly next to a star so that its image would fall on the more sensitive peripheral retina (which is mostly rods) Maximum sensitivity: minimum threshold for the perception of a brightness sensation occurred when only 6 quanta of light (photons) were stimulating the retina. Brightness contrast: our perception of brightness depends on the luminance of objects surrounding it (simultaneous brightness contrast) Lateral inhibition: visual neurons may be inhibited by the activity of nearby neurons; the inhibition acts laterally (or sideways) on adjacent neurons: mach bands:
