PSYCH 120A Lecture Notes - Lecture 5: Illusory Contours, Color Constancy, Retina
Document Summary
Inverse optics problem - reconstructing 3d from 2d retinal image. Contrast of white and black squares + shadow mental darkening. Ratio stays the same under different light conditions. But the amount of photons hitting your retina is different. Lightness constancy: our brain does not directly perceive the true brightness of objects in the world, but instead compares the brightness of a given item with others in its vicinity. Color constancy: our brain does not directly perceive the true color of objects in the world but instead compares the color of a given item with others in its vicinity. Frontal and parietal lobes are more activated in people who see the blue/black dress as white/gold indicating more top-down processing. Because line is not present in stimulus, must be due to top down feedback signals from higher cortical areas. Send signals back to as early as v1. Neural response to illusory line is weaker and delayed relative to regular visible line.
