Sensation. I. Basic Concepts II. Characteristics of Sensory Systems III. The Visual System

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1 Sensation I. Basic Concepts II. Characteristics of Sensory Systems III. The Visual System

2 Sensation The process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment. (from text) In other words The process of converting physical stimuli (light, sound, heat, pressure, etc ) into the language of the brain (action potentials & neurotransmitter release). Also known as transduction Strongly associated with bottom-up processing: analysis strongly shaped by sensory receptors.

3 Important Thresholds Absolute Threshold: The smallest possible amount of a stimulus that can be detected half (50%) of the time. Difference Threshold: The smallest possible difference between two stimuli that can be detected half (50%) of the time.

4 Some Questions to Consider. Would you notice a change of $10,000 in your bank account? Would everyone notice a change of $10,000 in their bank accounts?

5 Weber s Law The principle that, to be perceived as different, two stimuli must differ by a constant minimum percentage (rather than a constant minimum amount).

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12 Two Theories of Color Vision Trichromatic Theory blue, green, & red sensors Opponent Process Theory Blue-yellow, red-green, & black-white sensors

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16 Some Unusual Quotes N is sort of rubbery smooth, L is sort of the consistency of watery paint Letters also have vague personalities, but not as strongly as numerals do. The letter A is blue, B is red, C is a kind of light gray, D is orange I hear a note by one of the fellows in the band and it s one color. I hear the same note played by someone else and it s a different color. When I hear sustained musical tones, I see just about the same colors that you do, but I see them in textures. Basically, I taste words.

17 Synesthesia The perceptual experience of one sense that is evoked by another sense. For the typical person: A B C D E For someone with synesthesia: A B C D E

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20 Perception I. Review II. Important Points about Perception III. Object Perception IV. Depth & Distance Perception V. Illusions

21 I. Review Sensation: The process of converting physical stimuli into the language of the brain. Example: converting photons of light into nerve impulses Perception: The process of integrating, organizing, and interpreting sensory information. Example: recognizing the pattern of light that corresponds to the face of a friend

22 Bottom-Up versus Top-Down Bottom-Up Processing: Information processing that is strongly shaped by adding up the inputs of sensory receptors. Top-Down Processing: Information processing that is strongly shaped by higher level mental processes (such as expectations or beliefs).

23 II. Important Points about Perception Perceptual systems often misperceive the world Perceptions are strongly influenced by context Perceptions are strongly influenced by beliefs and expectations

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26 Do you see the woman?

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30 III. Object Perception

31 Figure-Ground Relationship

32 This lecture is brought to you by

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34 Gestalt Laws of Perceptual Grouping We perceive as belonging together objects that.. are close to each other (proximity). are similar to each other (similarity). are physically touching each other (connectedness). form continuous lines, curves, or patterns (continuity/good continuation) We also tend to perceive objects as more complete than they really are (closure).

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40 Depth Cues Monocular depth cues only require one eye Binocular depth cues require two eyes

41 Monocular Depth Cues

42 Relative Size

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46 Texture Gradient

47 Interposition

48 Relative Clarity

49 Relative Height

50 Relative Motion

51 Relative Motion Example 1 Example 2

52 Linear Perspective

53 Light & Shadow

54 Binocular Depth Cues Convergence Retinal/Binocular Disparity

55 IV. Illusions

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57 Illusions

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65 States of Consciousness I. Introduction II. Circadian Rhythms III. Sleep IV. Dreams

66 I. Introduction

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68 II. Circadian Rhythms

69 The SCN (Suprachiasmatic Nucleus)

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71 Other factors that follow circadian rhythms Immune system activity Medication effectiveness Tooth enamel Hearing, vision, taste, & smell sensitivity Pollen & dust sensitivity Pain sensitivity

72 III. Sleep

73 Sleep Myths (or at Least Half-Truths) We sleep to rest our brains We sleep to rest our bodies Sleep is a unitary state (all sleep is the same) Sleep is primarily a function of the environment (sleepy/boring places put you to sleep)

74 EEG & brain waves Measuring Sleep

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77 Dreams Dream Theories Freudian Dream Theory: dreams allow unconscious wish fulfillment Activation Synthesis Theory: dreams represent the higher brain s (cerebral cortex s) attempt to interpret random signals from the lower brain

78 4/21/2004

79 Learning I. Introduction II. Classical Conditioning III. Operant Conditioning IV. Cognition & Learning V. Observational Learning

80 II. Classical Conditioning

81 Classical Conditioning & Bear the Dog Presentation of a tofu hotdog Salivates Say the phrase, Tofu Pup? Salivates

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83 Unbeknownst to most students of psychology, Pavlov s first experiment was to ring a bell and cause his dog to attack Freud s cat.

84 Office clip

85 III. Operant Conditioning

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88 Variable -ratio Fixedratio Fixedinterval Variable -interval Student receives $50 for every 5 classes s/he attends. reinforce after specific number of correct responses Student receives $50 after s/he attends an average (sometimes more, sometimes less) of 5 classes reinforce after an average number of correct responses Student receives $50 every week (payday is constant e.g., Friday) reinforce 1 st correct response after a specific amount of time has passed Student receives $50 about every week (payday varies e.g., Thursday, Friday, Monday, etc ) reinforce 1 st correct response after an average amount of time has passed

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90 IV. Cognition and Learning

91 Cognitive Maps

92 Cognitive Maps

93 Latent Learning

94 Latent Learning

95 V. Observational Learning

96 V. Observational Learning

97 Bandura s Bobo Doll Study Illustrated the distinction between learning and performing Showed it is possible to learn but not perform