The Laws of Perception

Binocular Cues: depth cues that depend on using two eyes

• retinal disparity: the difference between the images from the retinas of each eye; by comparing these images, the brain perceives distance
• the larger the disparity, the closer the object
• 3-D movies exaggerate retinal disparity

Monocular Cues: depth cues that are available to either eye alone

• relative size: if two objects are similar in size, the larger object (with the greater retinal disparity) is perceived to be closer than the smaller object
• relative height: high objects are perceived to be far away
• texture gradient: as texture becomes less apparent and clear, we judge the surface to be going into the distance
• relative motion (motion parallax): as we move, for example in a car, closer objects seem to move past quickly in comparison to objects in the distance, which seem to move with us
• aerial perspective: far away objects appear to blurred or hazy due to the atmosphere
• linear perspective: parallel lines seem to converge in the distance; as they appear to converge more, the perceived distance grows
• interposition: when two objects overlap, the object that is being covered is perceived as being further away than the object that is covering it
• light and shadow: a shaded, dimmer object appears to be farther away than a bright object

phi phenomenon: an illusion of movement created when 2+ adjacent lights blink on and off quickly

perceptual constancy: despite changes in illumination and retinal images, we are able to perceive objects as unchanging with the same shape, size, color, and brightness

perceptual adaptation: our ability to adapt to changed visual input

perceptual set: a mental predisposition which influences (top-down) what we perceive and do not perceive