Chapter 5 Perceiving the World

Some Key Terms Perception: How we assemble sensations into meaningful patterns Bottom-up processing: Analyzing information starting at the bottom (small units) and going upward to form a complete perception Top-down processing: Pre-existing knowledge that is used to rapidly organize features into a meaningful whole

Selective Attention Giving priority to a particular incoming message.

Divided Attention Allotting mental space or effort to various tasks or parts of a task

Perceptual Expectancies Perceptual expectancy (set): Past experiences, motives, contexts, or suggestions that prepare us to perceive in a certain way

Attention and Perception Inattentional blindness: Failure to perceive a stimulus that is in plain view, but not the focus of attention Orientation response: Bodily changes that prepare an organism to receive information from a particular stimulus

Perceptual Grouping Figure–ground organization: Inborn; part of a stimulus stands out as an object (figure) against a plainer background (ground) Reversible gigure: Figure and ground that can be reversed

Fig. 5-6, p. 156

Gestalt Principles of Organization Nearness: Stimuli that are near each other tend to be grouped together Similarity: Stimuli that are similar in size, shape, color, or form tend to be grouped together Continuation, or continuity: Perceptions tend toward simplicity and continuity

Gestalt Principles of Organization (cont) Closure: Tendency to complete a figure so that it has a consistent overall form Contiguity: Nearness in time and space; perception that one thing has caused another Common region: Stimuli that are found within a common area tend to be seen as a group

More on Perception Size constancy: Perceived size of an object remains constant, despite changes in its retinal image size Native perception: A perceptual experience based on innate processes

Video: Size Constancy and Visual Illusions, Part 1

Fig. 5-15, p. 162

Video: Size Constancy and Visual Illusions, Part 2

Some More Key Terms Empirical perception: A perception strongly influenced by prior experience Shape constancy: The perceived shape of an object is unaffected by changes in its retinal image Brightness constancy: Apparent brightness of an object stays the same under changing lighting conditions

Fig. 5-9, p. 157

Fig. 5-1, p. 151

Depth Perception Definition: Ability to see three-dimensional space and to accurately judge distances Visual cliff: Apparatus that looks like the edge of an elevated platform or cliff on one side and a tabletop on the other

Depth Depth cues: Features of the environment, and messages from the body, that supply information about distance and space Binocular depth cue: Depth cue that can be sensed with two eyes Monocular depth cue: Depth cue that can be sensed with one eye

Fig. 5-4, p. 155

Muscular Cues for Depth Perception Retinal disparity: Discrepancy in the images that reach the right and left eyes Stereotopic vision: Three-dimensional sight; perception of space and depth caused by the fact that the eye receives different images

Fig. 5-12, p. 160

Pictorial Cues for Depth Features found in paintings, drawings, and photographs that supply information about space, depth, and distance; monocular depth cues

Linear Perspective Based on apparent convergence of parallel lines in environment

Overlap When one object partially blocks another

Texture Gradients Texture changes can contribute to depth perception; coarse texture implies closeness, fine texture implies distance

Relative Motion (Motion Parallax) Nearby objects move a lot as your head moves; distant objects move slightly

Video: Motion Parallax

Fig. 5-15, p. 162

Fig. 5-16, p. 163

Fig. 5-21, p. 165

Fig. 5-18, p. 164

Some Illusions Moon illusion: Apparent change in size that occurs as the moon moves from the horizon (large moon) to overhead (small moon) Apparent-distance hypothesis: Horizon seems more distant than the night sky

Fig. 5-8a, p. 156

Fig. 5-8b, p. 156

Fig. 5-29, p. 170

Fig. 5-20, p. 165

Video: Moon Illusion

Perceptual Learning Change in the brain that alters how we construct sensory information into precepts

Perceptual Habits Ingrained patterns of organization and attention –Other-race effect: Tendency to be better at recognizing faces from one’s own racial group than faces from other racial or ethnic groups –Active movement: Self-generated action; accelerates perceptual adaptation

Context Context: Information surrounding a stimulus; affects perception Frames of reference: Internal standards for judging stimuli

Fig. 5-24a, p. 166

Video: The Ames Room

Fig. 5-30, p. 170

Video: Ames Room Animation

Illusions: Is What You See What You Get? Illusion: Length, position, motion, curvature, or direction is constantly misjudged Hallucination: When people perceive objects or events that have no basis in external reality Stroboscopic movement: Illusory motion perceived when objects are shown in rapidly changing positions

Müller-Lyer Illusion Two equal-length lines tipped with inward or outward pointing V’s appear to be of different length; based on experience with edges and corners of rooms and buildings

Size-Distance Invariance Strict relationship between the distance an object lies from the eyes and the size of its image

Fig. 5-23a, p. 166

Fig. 5-23b, p. 166

Extrasensory Perception (ESP) Purported ability to perceive events in ways that cannot be explained by known capacities of sensory organs

Parapsychology Study of ESP and other psi phenomena (events that seem to defy accepted scientific laws)

Parapsychological “Abilities” Clairvoyance: Purported ability to perceive events at a distance or through physical barriers Telepathy: Purported ability to read minds Precognition: Purported ability to accurately predict the future Psychokinesis (mind over matter): Purported ability to influence inanimate objects by willpower

More ESP Terms Zener cards: Deck of 25 cards, each having one of five symbols Run of luck: Statistically unusual outcome that could occur by chance alone (e.g., getting five heads in a row, two jackpots within six pulls of a slot machine)

Stage ESP Simulation of ESP for entertainment purposes Conclusion: Existence of ESP has NOT been scientifically demonstrated; positive results are usually inconclusive and easily criticized

A Final Prediction Be skeptical! If it seems too good to be true, it probably is!

Fig. 5-32, p. 172

Fig. 5-33a, p. 174

Fig. 5-33b, p. 174

Fig. 5-33c, p. 174