1. PSYCHOLOGY (9th Edition) David Myers
PowerPoint Slides
Aneeq Ahmad
Henderson State University
Worth Publishers, © 2010

2. Sensation and Perception Chapter 6

3. Sensation Sensing the World: Some Basic Principles Vision Thresholds
Sensory Adaptation
Vision
The Stimulus Input: Light Energy
The Eye
Visual Information Processing
Color Vision

4. Other Important Senses
Hearing
The Stimulus Input: Sound Waves
The Ear
Hearing Loss and Deaf Culture
Other Important Senses
Touch
Pain
Taste
Smell

5. Perceptual Organization
Form Perception
Depth Perception
Motion Perception
Perceptual Constancy

6. Perceptual Interpretation
Sensory Deprivation and Restored Vision
Perceptual Adaptation
Perceptual Set
Perception and the Human Factor

7. Is There Extrasensory Perception?
Claims of ESP
Premonitions or Pretensions?
Putting ESP to Experimental Test

8. Sensation & Perception
How do we construct our representations of the external world?
To represent the world, we must detect physical energy (a stimulus) from the environment and convert it into neural signals. This is a process called sensation.
When we select, organize, and interpret our sensations, the process is called perception.
Preview Question 1: What are sensation and perception? What do we mean by bottom-up processing and top-down processing?

9. Bottom-up Processing
Analysis of the stimulus begins with the sense receptors and works up to the level of the brain and mind.
Letter “A” is really a black blotch broken down into features by the brain that we perceive as an “A.”

10. THE CHT Top-Down Processing
Information processing guided by higher-level mental processes as we construct perceptions, drawing on our experience and expectations.
THE CHT

11. Making Sense of Complexity
Our sensory and perceptual processes work together to help us sort out complex images.
“The Forest Has Eyes,” Bev Doolittle

12. Senses are nature’s gift that suit an organism’s needs.
Sensing the World
Senses are nature’s gift that suit an organism’s needs.
A frog feeds on flying insects; a male silkworm moth is sensitive to female sex-attractant odor; and we as human beings are sensitive to sound frequencies that represent the range of human voice.

13. Exploring the Senses What stimuli cross our threshold for
conscious awareness?

14. Psychophysics
A study of the relationship between physical characteristics of stimuli and our psychological experience with them.
Physical World
Psychological World
Light
Brightness
Sound
Volume
Pressure
Weight
Sugar
Sweet

15. Thresholds
Absolute Threshold: Minimum stimulation needed to detect a particular stimulus 50% of the time.
Proportion of “Yes” Responses
Stimulus Intensity (lumens)
Preview Question 2: What is are the absolute and difference thresholds, and do stimuli below the absolute threshold have any influence?

16. Subliminal Threshold
Subliminal Threshold: When stimuli are below one’s absolute threshold for conscious awareness.
Kurt Scholz/ Superstock

17. Weber’s Law
Two stimuli must differ by a constant minimum percentage (rather than a constant amount), to be perceived as different. Weber fraction: k = dI/I.
Stimulus
Constant (k)
Light 8%
Weight 2%
Tone 3%

18. Sensory Adaptation
Diminished sensitivity as a consequence of constant stimulation.
Preview Question 3: What is the function of sensory adaptation?
Put a band aid on your arm and after awhile
you don’t sense it.

19. Now you see, now you don’t

20. Vision

21. Transduction
In sensation, the transformation of stimulus energy (sights, sounds, smells) into neural impulses.

22. The Stimulus Input: Light Energy
Visible
Spectrum
Preview Question 4: What are the energy that we see as visible light?
Both Photos: Thomas Eisner

23. Physical Characteristics of Light
Wavelength (hue/color)
Intensity (brightness)

24. Wavelength (Hue)
Hue (color) is the dimension of color determined by the wavelength of the light.
Wavelength is the distance from the peak of one wave to the peak of the next.

25. Different wavelengths of light result
Wavelength (Hue)
Violet
Indigo
Blue
Green
Yellow
Orange
Red
400 nm
700 nm
Short wavelengths
Long wavelengths
Different wavelengths of light result
in different colors.

26. Intensity (Brightness)
Intensity: Amount of energy in a wave determined by the amplitude. It is related to perceived brightness.

27. Intensity (Brightness)
Blue color with varying levels of intensity.
As intensity increases or decreases, blue color
looks more “washed out” or “darkened.”

28. The Eye
Preview Question 5: How does the eye transform light energy into neural messages?

29. Parts of the eye
Cornea: Transparent tissue where light enters the eye.
Iris: Muscle that expands and contracts to change the size of the opening (pupil) for light.
Lens: Focuses the light rays on the retina.
Retina: Contains sensory receptors that process visual information and sends it to the brain.

30. The Lens
Lens: Transparent structure behind the pupil that changes shape to focus images on the retina.
Accommodation: The process by which the eye’s lens changes shape to help focus near or far objects on the retina.

31. Retina
Retina: The light-sensitive inner surface of the eye, containing receptor rods and cones in addition to layers of other neurons (bipolar, ganglion cells) that process visual information.

32. Optic Nerve, Blind Spot & Fovea
Optic nerve: Carries neural impulses from the eye to the brain. Blind Spot: Point where the optic nerve leaves the eye because there are no receptor cells located there. Fovea: Central point in the retina around which the eye’s cones cluster.

33. Test your Blind Spot
Use your textbook. Close your left eye, and fixate your right eye on the black dot. Move the page towards your eye and away from your eye. At some point the car on the right will disappear due to a blind spot.

34. Photoreceptors
E.R. Lewis, Y.Y. Zeevi, F.S Werblin, 1969

35. Bipolar & Ganglion Cells
Bipolar cells receive messages from photoreceptors and transmit them to ganglion cells, which converge to form the optic nerve.

36. Visual Information Processing
Optic nerves connect to the thalamus in the middle of the brain, and the thalamus connects to the visual cortex.
Preview Question 6: How does the brain process visual information?

37. Feature Detection
Nerve cells in the visual cortex respond to specific features, such as edges, angles, and movement.
Ross Kinnaird/ Allsport/ Getty Images

38. Shape Detection
Specific combinations of temporal lobe activity occur as people look at shoes, faces, chairs and houses.
Ishai, Ungerleider, Martin and Haxby/ NIMH

39. Visual Information Processing
Processing of several aspects of the stimulus simultaneously is called parallel processing. The brain divides a visual scene into subdivisions such as color, depth, form, movement, etc.

40. From Sensation to Recognition

41. Color Vision
Trichromatic theory: Young and von Helmholtz suggested that the eye must contain three receptors that are sensitive to red, blue and green colors.
Standard stimulus
Preview Question 7: What theories help us understand color vision?
Comparison stimulus
Max
Medium
Low
Blue
Green
Red

42. Color Blindness
Genetic disorder in which people are blind to green or red colors. This supports the Trichromatic theory.
Ishihara Test

43. Opponent Colors Gaze at the middle of the flag for about 30
Seconds. When it disappears, stare at the dot and report
whether or not you see Britain's flag.

44. Hearing

45. Hearing The Stimulus Input: Sound Waves
Sound waves are compressing and expanding air molecules.
Preview Question 8: What are the characteristics of air pressure waves that we hear as sound?

46. Sound Characteristics
Frequency (pitch)
Intensity (loudness)

47. The Ear
Dr. Fred Hossler/ Visuals Unlimited
Preview Question 9: How does the ear transform sound energy into neural messages?

48. The Ear Outer Ear: Collects and sends sounds to the eardrum.
Middle Ear: Chamber between eardrum and cochlea containing three tiny bones (hammer, anvil, stirrup) that concentrate the vibrations of the eardrum on the cochlea’s oval window.
Inner Ear: Innermost part of the ear, containing the cochlea, semicircular canals, and vestibular sacs.

49. Cochlea
Cochlea: Coiled, bony, fluid-filled tube in the inner ear that transforms sound vibrations to auditory signals.

50. Intensity (Loudness)
Intensity (Loudness): Amount of energy in a wave, determined by the amplitude, relates to the perceived loudness.

51. Loudness of Sound
Richard Kaylin/ Stone/ Getty Images
120dB
70dB

52. Frequency (Pitch)
Frequency (pitch): The dimension of frequency determined by the wavelength of sound.
Wavelength: The distance from the peak of one wave to the peak of the next.
Preview Question 10: What theories help us understand pitch perception?

53. Localization of Sounds
Because we have two ears, sounds that reach one ear faster than the other ear cause us to localize the sound.
Preview Question 11: How do we locate sounds?

54. 1. Intensity differences
Localization of Sound
1. Intensity differences
2. Time differences
Time differences as small as 1/100,000 of a second can cause us to localize sound. The head acts as a “shadow” or partial sound barrier.
Preview Question 12: What are the common causes of hearing loss, and why does controversy surround cochlear implants?

55. Touch
The sense of touch is a mix of four distinct skin senses—pressure, warmth, cold, and pain.
Preview Question 13: How do we sense touch and sense our body’s position and movement? How do we experience pain?
Bruce Ayers/ Stone/ Getty Images

56. Skin Senses
Only pressure has identifiable receptors. All other skin sensations are variations of pressure, warmth, cold and pain.
Pressure
Vibration
Vibration
Burning hot
Cold, warmth and pain

57. Ashley Blocker (right) feels neither pain
Pain tells the body that something has gone wrong. Usually pain results from damage to the skin and other tissues. A rare disease exists in which the afflicted person feels no pain.
AP Photo/ Stephen Morton
Ashley Blocker (right) feels neither pain
nor extreme hot or cold.

58. Biopsychosocial Influences

59. Gate-Control Theory
Melzack and Wall (1965, 1983) proposed that our spinal cord contains neurological “gates” that either block pain or allow it to be sensed.
Gary Comer/ PhototakeUSA.com

60. Pain Control
Pain can be controlled by a number of therapies including, drugs, surgery, acupuncture, exercise, hypnosis, and even thought distraction.
Todd Richards and Aric Vills, U.W.
©Hunter Hoffman,

61. Taste
Traditionally, taste sensations consisted of sweet, salty, sour, and bitter tastes. Recently, receptors for a fifth taste have been discovered called “Umami”.
Preview Question 14: How do we experience taste?
Sweet
Sour
Salty
Bitter
Umami
(Fresh
Chicken)

62. Sensory Interaction
When one sense affects another sense, sensory interaction takes place. So, the taste of strawberry interacts with its smell and its texture on the tongue to produce flavor.

63. Smell
Like taste, smell is a chemical sense. Odorants enter the nasal cavity to stimulate 5 million receptors to sense smell. Unlike taste, there are many different forms of smell.
Preview Question 15: How do we experience smell?

64. Smell and Memories
The brain region for smell (in red) is closely connected with the brain regions involved with memory (limbic system). That is why strong memories are made through the sense of smell.

65. Body Position and Movement
The sense of our body parts’ position and movement is called kinesthesis. The vestibular sense monitors the head (and body’s) position.
Bob Daemmrich/ The Image Works
Whirling Dervishes
Wire Walk

66. Perceptual Organization
How do we form meaningful perceptions from sensory information?
We organize it. Gestalt psychologists showed that a figure formed a “whole” different than its surroundings.
Preview Question 16: How did the Gestalt psychologists understand perceptual organization?

67. Form Perception
Organization of the visual field into objects (figures) that stand out from their surroundings (ground).
Preview Question 17: How do figure-ground and grouping principles contribute to our perceptions?
Time Savings Suggestion, © 2003 Roger Sheperd.

68. Grouping
After distinguishing the figure from the ground, our perception needs to organize the figure into a meaningful form using grouping rules.

69. Grouping & Reality
Although grouping principles usually help us construct reality, they may occasionally lead us astray.
Both photos by Walter Wick. Reprinted from GAMES
Magazine. .© 1983 PCS Games Limited Partnership

70. Depth Perception
Depth perception enables us to judge distances. Gibson and Walk (1960) suggested that human infants (crawling age) have depth perception. Even newborn animals show depth perception.
Preview Question 18: How do we see the world in three dimensions?
Innervisions
Visual Cliff

71. Binocular Cues
Retinal disparity: Images from the two eyes differ. Try looking at your two index fingers when pointing them towards each other half an inch apart and about 5 inches directly in front of your eyes. You will see a “finger sausage” as shown in the inset.

72. Monocular Cues
Relative Size: If two objects are similar in size, we perceive the one that casts a smaller retinal image to be farther away.

73. Monocular Cues
Interposition: Objects that occlude (block) other objects tend to be perceived as closer.
Rene Magritte, The Blank Signature, oil on canvas,
National Gallery of Art, Washington. Collection of
Mr. and Mrs. Paul Mellon. Photo by Richard Carafelli.

74. Monocular Cues
Relative Height: We perceive objects that are higher in our field of vision to be farther away than those that are lower.
Image courtesy of Shaun P. Vecera, Ph. D.,
adapted from stimuli that appered in Vecrera et al., 2002

75. Monocular Cues
Relative motion: Objects closer to a fixation point move faster and in opposing direction to those objects that are farther away from a fixation point, moving slower and in the same direction.
Preview Question 19: How do we perceive motion?

76. Monocular Cues
Linear Perspective: Parallel lines, such as railroad tracks, appear to converge in the distance. The more the lines converge, the greater their perceived distance.
© The New Yorker Collection, 2002, Jack Ziegler
from cartoonbank.com. All rights reserved.

77. Monocular Cues
Light and Shadow: Nearby objects reflect more light into our eyes than more distant objects. Given two identical objects, the dimmer one appears to be farther away.
From “Perceiving Shape From Shading” by Vilayaur
S. Ramachandran. © 1988 by Scientific American, Inc.
All rights reserved.

78. Perceptual Constancy
Perceiving objects as unchanging even as illumination and retinal images change.
Preview Question 20: How do perceptual constancies help us to organize our sensations into meaningful perceptions?

79. Color Constancy
Perceiving familiar objects as having consistent color even when changing illumination filters the light reflected by the object.
Color Constancy

80. Size-Distance Relationship
The distant monster (below, left) and the top red bar (below, right) appear bigger because of distance cues.
Alan Choisnet/ The Image Bank
From Shepard, 1990

81. Size-Distance Relationship
Both girls in the room are of similar height. However, we perceive them to be of different heights as they stand in the two corners of the room.
Both photos from S. Schwartzenberg/ The Exploratorium

82. The Ames room is designed to demonstrate the size-distance illusion.

83. The color and brightness of square A and B are the same.
Lightness Constancy
Courtesy Edward Adelson
The color and brightness of square A and B are the same.

84. Perceptual Interpretation
Immanuel Kant ( ) maintained that knowledge comes from our inborn ways of organizing sensory experiences.
John Locke ( ) argued that we learn to perceive the world through our experiences.
How important is experience in shaping our
perceptual interpretation?

85. Sensory Deprivation & Restored Vision
After cataract surgery, blind adults were able to regain sight. These individuals could differentiate figure and ground relationships, yet they had difficulty distinguishing a circle and a triangle (Von Senden, 1932).
Preview Question 21: What does research on sensory restriction and restored vision reveal about the effects of experience?

86. Facial Recognition
After blind adults regained sight, they were able to recognize distinct features, but were unable to recognize faces. Normal observers also show difficulty in facial recognition when the lower half of the pictures are changed.
Courtesy of Richard LeGrand

87. Sensory Deprivation
Kittens raised without exposure to horizontal lines later had difficulty perceiving horizontal bars.
Blakemore & Cooper (1970)

88. Perceptual Adaptation
Visual ability to adjust to an artificially displaced visual field, e.g., prism glasses.
Preview Question 22: How adaptable is our ability to perceive?
Courtesy of Hubert Dolezal

89. Perceptual Set
A mental predisposition to perceive one thing and not another. What you see in the center picture is influenced by flanking pictures.
Preview Question 23: How do our expectations, contexts, and emotions influence our perceptions?
From Shepard, 1990.

90. Perceptual Set Other examples of perceptual set.
Frank Searle, photo Adams/ Corbis-Sygma
Dick Ruhl
(a) Loch ness monster or a tree trunk; (b) Flying saucers or clouds?

91. Context Effects Context can radically alter perception.
Is the “magician cabinet” on the floor or hanging from the ceiling?

92. Context instilled by culture also alters perception.
Cultural Context
Context instilled by culture also alters perception.
To an East African, the woman sitting is balancing a metal box on her head, while the family is sitting under a tree.

93. Is perception innate or acquired?
Perception Revisited
Is perception innate or acquired?
Preview Question 24: How do human factors psychologists work to create user-friendly machines and work settings?

94. Is There Extrasensory Perception?
Perception without sensory input is called extrasensory perception (ESP). A large percentage of scientists do not believe in ESP.
Preview Question 25: What are the claims of ESP, and what have most research psychologists concluded after putting these claims to the test?

95. Claims of ESP
Telepathy: Mind-to-mind communication. One person sending thoughts and the other receiving them.
Clairvoyance: Perception of remote events, such as sensing a friend’s house on fire.
Precognition: Perceiving future events, such as a political leader’s death.