Understanding Perception: Key Concepts and Principles for Enhancing Awareness

1. Chapter 5Perceiving the World

2. 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

3. Selective Attention • Giving priority to a particular incoming message.

4. Selective Attention Exercise • Reading Aloud.

5. Discuss • How has perceptual learning affected your ability to safely drive a car? For example, what do you pay attention to at intersections? Where do you habitually look as you are driving?

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

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

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

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

10. Fig. 5-4, p. 155

11. Fig. 5-6, p. 156

12. 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

13. 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

14. Video: Size Constancy and Visual Illusions, Part 1

15. Video: Size Constancy and Visual Illusions, Part 2

16. 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

17. Fig. 5-9, p. 157

18. Fig. 5-1, p. 151

19. 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

20. 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

21. 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

22. Fig. 5-12, p. 160

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

24. Fig. 5-15, p. 162

25. Linear Perspective • Based on apparent convergence of parallel lines in environment

26. Overlap • When one object partially blocks another

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

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

29. Video: Motion Parallax

30. Fig. 5-15, p. 162

31. Fig. 5-16, p. 163

32. Fig. 5-21, p. 165

33. Fig. 5-18, p. 164

34. Line on page-Exercise

35. 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

36. Video: Moon Illusion

37. Fig. 5-8a, p. 156

38. Fig. 5-8b, p. 156

39. Fig. 5-29, p. 170

40. Fig. 5-20, p. 165

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

42. 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

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

44. Fig. 5-24a, p. 166

45. Video: The Ames Room

46. Video: Ames Room Animation

47. 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 (cartoon flipbook)

48. 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

49. Fig. 5-30, p. 170

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