Chapter 6 Perception

Transform meaningless sensations into meaningful perceptions

The Perception Paradox—misperceiving reality

Perception failure — our perceptual

experience of a stimulus differs from the actual characteristics of that stimulus

Three approaches to perception Computational approach — focuses on how computations by the nervous

system translate raw sensory stimulation into an experience of reality

Constructivist approach — the perceptual system uses fragments of sensory

information to construct an image of reality Ecological approach — humans and other species are so well adapted to

their natural environment that many aspects of the world are perceived without requiring higher-level analysis and inferences

Selective Attention—the focusing of conscious awareness on a particular stimulus

Cocktail party effect—the ability to attend selectively to only one voice among many

The experiments （视而不见） U. Neisser(1979) and … Can unnoticed stimuli affect us? “We stood by the bank” (river or money)

Perceptual Illusions

Optical ~: misjudge length, position, motion, curvature, or direction

A classic illusion created by Franz Müller-Lyer, 1889

The Poggenddorff illusion

The Ebbinghaus illusion

Zollner illusion

The face looks familiar

Perceptual Organization

Gestalt — an organized whole — the whole may exceed the

sum of its partsForm perception

Figure and Ground — the organization of the visual field into objects (the figure) that stand out from their surroundings (the ground)

A face or an Eskimo

An old man or two young lovers

A young lady or a man playing saxophone

Salvador Dali’s Slave Market with the Disappearing Bust of Voltaire (1940)

Grouping — the perceptual tendency

to organize stimuli into coherent groups

Proximity

Similarity

Continuity

Closure

Depth Perception—learned or innate Visual Cliff

Binocular Cues

Retinal disparity Convergence

Monocular Cues: relative size —if separate objects are expected to be of the

same size, the larger ones are seen as closer

Linear perspective — parallel lines appear to converge with distance

Texture gradient — a texture is coarser for near areas and finer for more distant ones

Interposition — the shapes of near objects overlap or mask of more distant ones

Height in plane — near objects are low in the visual field; more distant ones are higher up

Light and shadow—patterns of light and dark suggest shadows that can create an impression of three-dimensional forms

Motion Perception—phi phenomenon

Perceptual Constancy

ShapeSizeLightnessColor

Color depends on context

Perceptual Adaptation

Perceptual Set

a mental predisposition to perceive one thing and not another

Recognizing faces

Our schemas for faces prime us to see facial patterns

Average face?

平均脸：more attractive?

Recognizing the Perceptual World

Bottom-up processingTop-down processingNetwork processing

Perception and Human Factor