Fig61

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Fig62

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Fig5_14

05_12

InRev5a

InRev4bInRev2aPRINCIPLES OF PERCEPTUAL ORGANIZATION AND CONSTANCY

Certain objects or sounds are automatically identified as figures, whereas others become meaningless background.

Properties of stimuli lead us to automatically group them together. These include proximity, similarity, continuity, closure, texture, simplicity, common fate, and common region.

Knowing an object’s two-dimensional position (left and right, up and down) and distance enables us to locate it. The image on the retina and the orientation of the head position provide information about the two-dimensional position of visual stimuli; auditory localization relies on differences in the information received by the ears. Depth or distance perception uses stimulus cues such as occlusion, relative size, texture gradients, linear perspective, clarity, color, and shadow.

Objects are perceived as constant in size, shape, color, and other properties, despite changes in their retinal images.

Principle

Figure-ground processing

Grouping (Gestalt laws)

Perception of location and depth

Perceptual constancy

You see a person standing against a building, not a building with a person-shaped hole in it.

People who are sitting together, or are dressed similarly, are perceived as a group.

Large, clear objects appear closer than small, hazy objects.

A train coming toward you is perceived as getting closer, not larger; a restaurant sign is perceived as rotating, not changing shape.

Description Example

05_18

Presentedstimulus

Featuresdetected

Featurescombined

Patternsrecognized

InRev5b

InRev5aInRev4bInRev2aMECHANISMS OF PATTERN RECOGNITION

Raw sensations from the eye or the ear are analyzed into basic features, such as color or movement; these features are then recombined at higher brain centers, where they are compared to stored information about objects or sounds.

Knowledge of the world and experience in perceiving allow people to make inferences about the identity of stimuli, even when the quality of raw sensory information is low.

Recognition depends on communication among feature-analysis systems operating simultaneously and enlightened by past experience.

Mechanism

Bottom-up processing

Top-down processing

Network, or PDP, processing

You recognize a dog as a dog because its physical features—four legs, barking, panting—match your perceptual category for “dog.”

On a dark night, a small, vaguely seen blob pulling on the end of a leash is recognized as a dog because the stimulus occurs at a location where we would expect a dog to be.

A dog standing behind a picket fence will be recognized even though each disjointed “slice” of the stimulus may not look like a dog.

Description Example

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RED RED GREEN

InRev5c

InRev5bInRev5aInRev4bInRev2aATTENTION

Directs sensory and perceptual systems toward stimuli

Selects specific information for further processing

Allocates mental energy to process information

Regulates the flow of resources necessary for performing a task or coordinating multiple tasks

Characteristics

Improves mental functioning

Requires effort

Has limits

Overt orienting (e.g., cupping your ear to hear a whisper)

Covert orienting (e.g., thinking about spring break while looking at the notes in front of you)

Voluntary control (e.g., purposefully looking for cars before crossing a street)

Involuntary control (e.g., losing your train of thought when you’re interrupted by a thunderclap)

Automatic processing (e.g., no longer thinking about grammar rules as you become fluent in a foreign language)

Divided attention (e.g., looking for an open teammate while you dribble a soccer ball down the field)

Functions Mechanisms

L5

SOCIAL COGNITION

Can subliminal stimuli influence our judgments about people? (p. 624)

HUMAN DEVELOPMENT

What does the world look like to infants?  (p. 163)

SENSATION

How can the senses be fooled? (p. 154)

LINKAGESto Perception