Sensation and Perception An Invitation to Psychology Second Edition Carole Wade Carole Tavris

1. Sensation and PerceptionAn Invitation to PsychologySecond EditionCarole WadeCarole Tavris Porterville College Psychology 101 Online Norris Edwards

2. Thoughts About Sensation & Perception • How sense-luscious the world is. • Diane Ackerman • From a swirling sea of energies, each sense selects its own. • Daniel P. Kimble • The eye, or really the mind behind the eye, can be tricked into interpretive flips . . . • Roger N. Shepard

3. Sensation and Perception • Measuring the Sensory Experience • Sensation • Perception • Extrasensory Perception

4. Sensation & Perception Processes

5. Psychophysics • Psychophysics • The study of the relationship between physical stimulation and subjective sensations. • Signal-Detection Theory • The theory that detecting a stimulus is jointly determined by the signal and the subject’s response criterion.

6. Thresholds • Absolute Threshold • The smallest amount of stimulation that can be detected • Just Noticeable Difference • The smallest amount of change in a stimulus that can be detected

7. Absolute Sensory Thresholds • Vision: A single candle flame from 30 miles on a dark, clear night • Hearing: The tick of a watch from 20 feet in total quiet • Smell: 1 drop of perfume in a 6-room apartment • Touch: The wing of a bee on your cheek, dropped from 1 cm • Taste: 1 tsp. Sugar in 2 gal. water

8. The Electromagnetic Spectrum

9. The Electromagnetic Spectrum

10. Structures of the Human Eye

11. Visual Pathways

12. The Retina

13. Are numerous and found primarily in the peripheral retina Have a lower threshold for activation Have lower acuity Do not process color Are concentrated primarily in the fovea Have a higher threshold for activation Have higher acuity Process color Differences Between Rods and Cones Cones Rods

14. Hubel & Wiesel’s Experiment • Some cells in the visual cortex respond only to certain types of visual information • For example, a diagonal line moving up and down • These cells are called feature detectors

15. Trichromatic Theory • T. Young (1802) & H. von Helmholtz (1852) both proposed that the eye detects 3 primary colors • red, blue, & green • All other colors can be derived by combining these three

16. Afterimages

17. The Color Wheel • Spectral colors vary from Violet-Blue to Red • 470 to 700 nanometer wavelength • Purple and red-purple are non-spectral colors • Not found on the visible electromagnetic spectrum • Across the wheel, each color has its complement

18. Test of Color Deficiency

19. The Human Ear

20. Auditory Localization • Sounds from different directions are not identical as they arrive at left and right ears • Loudness • Timing • Phase • The brain calculates a sound’s location by using these differences

21. Olfactory System

22. Taste Buds • Photograph of tongue surface (top), magnified 75 times • 10,000 taste buds line the tongue and mouth • Taste receptors are down inside the “bud” • Children have more taste buds than adults

23. Sensitivity to Touch

24. PerceptionMotivation and Attention: • We do not perceive everything in our environment; our motives greatly influences our perception • Driving down the road, very hunger all you seem to notice is fast food billboards. • Then you notice that the gas gauge is running on empty. • How are your perception altered?

25. Attention • We cannot possibly attend to and process all of the stimuli received by our sensory systems • Dichotic listening exercises (Goodwin, 1988) • Divided Attention • “cocktail party phenomenon” (Cherry & Bowles, 1960)

26. Basic Perceptual Abilities: Patterns and Constancies • Pattern Perception • Feature detectors • Feature Analysis Theory of Pattern Perception (Lindsay & Norman, 1977) • Theory of pattern perception stating the we perceive basis elements of an object and assemble them mentally to create the complete object.

27. Basic Perceptual Abilities: Patterns and Constancies • Perceptual Constancy • Shape Constancy • Size Constancy • C.M. Turnbull (1961) • Auditory Constancies • How are we able to recognize a melody, when it is played on different instruments and in different keys?

28. Shape Constancy • Even though these images cast shadows of different shapes, we still see the quarter as round

29. Depth Perception • The ability to perceive our world three – dimensionally. Two type of cues: • Binocular cues • Adjustments of the eye muscles • Binocular Disparity • Monocular cues • Superposition • Texture Gradient • Linear Perspective • Relative Brightness

30. The Visual Cliff • Devised by Eleanor Gibson and Richard Walk (1960) to test depth perception • Glass surface, with checkerboard underneath at different heights • Visual illusion of a cliff • Baby can’t fall • Mom stands across the gap • Babies aren’t afraid until about the age they can crawl

31. Gestalt Principle of Perceptual Organization • The founders of Gestalt psychology • Max Wertheimer • Wolfgang Kohler • Kurt Koffka • We are born with the ability to organize the elements of our perceptual world in very predictable ways. • The goal of these automatic processes is to produce the most complete perception of the environment.

32. Figure and Ground • “It may take a magician to pull a rabbit out of a hat, but we all possess sufficient magic to pull a duck out of a rabbit.” • R. N. Shephard, 1990

33. Figure and Ground

34. Principles of Grouping • Proximity • Seeing 3 pair of lines in A • Similarity • Seeing columns of orange and red dots in B • Continuity • Seeing lines that connect 1 to 2 and 3 to 4 in C • Closures • Seeing a horse in D

35. Perception of Movement • Theater marquees and electronic billboards suggestion that the words are moving across the sign. But are they? • Apparent Motion • The illusion of movement in a stationary object. • Movies, television, videocassette • Autokinetic effect

36. Perceptual Hypotheses and Illusions • Perceptual Hypothesis • Inference about the nature of stimuli received from the environment • Perceptual Illusions • Misperceptions or interpretations of stimuli that do not correspond to the sensations received.

37. The Ames Room • A specially-built room that makes people seem to change size as they move around in it • The room is not a rectangle, as viewers assume it is • A single peephole prevents using binocular depth cues

38. Contemporary Issue and Findings • Parallel Processing (Friedman-Hill & Wolfe, 1995 • Processing does not occur in a strictly sequential manner (Zeki, 1993) • Visual Search • Five different cones (Neitz, Neitz & Grishok, 1995) • Application of Basic Research • Dyslexia

39. Perceptual Set • What you see in the center figures depends on the order in which you look at the figures: • If you scan from the left, see an old woman • If you scan from the right, see a woman’s figure

40. Context Effects • The same physical stimulus can be interpreted differently • We use other cues in the situation to resolve ambiguities • Is this the letter B or the number 13?

41. The Ponzo Illusion • Linear perspective provides context • Side lines seem to converge • Top line seems farther away • But the retinal images of the red lines are equal!

42. Parapsychology • Gallop & Newport (1991) survey • 93 percent believed in at least one paranormal or psychic phenomenon • 1/3 believed in reincarnation • 1/3 believed in communication with the dead • ½ believed that their dreams could predict event such as the death of a family member.

43. Parapsychology • J. B. Rhine conducted many experiments on ESP using stimuli such as these Zener Cards • Rhine believed that his evidence supported the existence of ESP, but his findings were flawed

44. Psychics exploit unquestioning minds “Psychic Abscam” (1983) “A psychic is an actor playing the role of a psychic”, Daryl Bem (1984) Layton and Turnbull, clairvoyance experiment. Daryl Bem and Charles Honorton (1994) The Ganzfeld Procedure Thinking Critically About ESP