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Chpters 5-6

  1. 1. <ul><li>Chapters 5-6 Sensation and Perception </li></ul><ul><li>Consciousness </li></ul>
  2. 2. Windows on the World <ul><li>How we understand our world </li></ul><ul><li>Two basic processes: </li></ul><ul><ul><li>Sensation: Gathering information </li></ul></ul><ul><ul><li>Perception: Interpreting information </li></ul></ul>
  3. 3. Basic Principles <ul><li>Sensation </li></ul><ul><ul><li>The process of receiving stimulus energies from the external environment </li></ul></ul><ul><li>Transduction </li></ul><ul><ul><li>The process of transforming physical energy into electrochemical energy (action potential) </li></ul></ul><ul><li>Perception </li></ul><ul><ul><li>The process of organizing and interpreting sensory information </li></ul></ul>
  4. 4. Sensation <ul><li>Sensory Receptors </li></ul><ul><ul><li>Specialized cells that detect and transmit sensory information to the brain </li></ul></ul><ul><ul><li>These cells respond selectively to stimulation </li></ul></ul><ul><ul><li>Cells send signals via distinct neural pathways </li></ul></ul>
  5. 5. Figure 5-1 Sensation and Perception <ul><li>Can you identify anything meaningful in these patterned shapes? </li></ul><ul><li>Sensation is detecting the different shapes </li></ul><ul><li>However, organizing it into something is the process of perception. </li></ul>
  6. 6. Sensation and Perception <ul><li>Look at the three boxes below. Write down what color you think each box represents. </li></ul>
  7. 7. Sensation and Perception <ul><li>The boxes are colored in lime, turquoise and rose. </li></ul><ul><li>If each student is receiving the same sensation of color from each of the boxes, then why do some students have different perceptions of the colors? </li></ul>
  8. 8. Sensation <ul><li>Photoreception (Vision) </li></ul><ul><ul><li>Detection of light </li></ul></ul><ul><li>Mechanoreception (Touch) </li></ul><ul><ul><li>Detection of pressure, vibration, and movement </li></ul></ul><ul><li>Chemoreception (Smell and Taste) </li></ul><ul><ul><li>Detection of chemical stimuli </li></ul></ul>
  9. 9. Absolute Thresholds <ul><li>Absolute threshold : </li></ul><ul><ul><li>the lowest level of a stimulus </li></ul></ul><ul><ul><li>detected half the time </li></ul></ul><ul><li>Subliminal stimulus </li></ul><ul><ul><li>detected only up to 49% of the time </li></ul></ul><ul><ul><li>short-lived, no long-term consequences </li></ul></ul>
  10. 10. Absolute Thresholds <ul><li>Absolute thresholds can vary across individuals </li></ul><ul><ul><li>Limitations and variances </li></ul></ul><ul><ul><ul><li>Age </li></ul></ul></ul><ul><ul><ul><li>Abilities </li></ul></ul></ul><ul><ul><ul><li>Experiences </li></ul></ul></ul><ul><ul><li>Fatigue: Life and death implications </li></ul></ul>
  11. 11. Difference Thresholds <ul><li>Detection of change or discrimination between stimuli </li></ul><ul><ul><li>JND: </li></ul></ul><ul><ul><ul><li>smallest difference between two stimuli </li></ul></ul></ul><ul><ul><ul><li>detected half the time </li></ul></ul></ul><ul><ul><li>JNDs vary from person to person </li></ul></ul><ul><ul><li>JND’s vary by sense </li></ul></ul><ul><ul><ul><li>Ex) hearing compared to taste </li></ul></ul></ul>
  12. 12. Difference Thresholds <ul><li>Weber’s Law: </li></ul><ul><li>For a person to notice change: </li></ul><ul><ul><li>A weak or a small stimulus does not require much change </li></ul></ul><ul><ul><li>Strong or large stimulus requires a proportionately greater change </li></ul></ul><ul><ul><li>Ex) 2 nd vs. 80 th candle on a birthday cake in a dark room </li></ul></ul>
  13. 13. Sensory Adaptation <ul><li>Sensory Adaptation </li></ul><ul><ul><li>responsiveness to stimuli diminishes with repeated exposure </li></ul></ul><ul><li>Evolutionary Value vs. Everyday Value </li></ul><ul><li>Smell adapts quickly </li></ul><ul><ul><li>Ex) Fish store or being on a farm </li></ul></ul><ul><li>Vision prevents adaptation </li></ul>
  14. 14. Processing Light <ul><li>Color is produced/created by the nervous system in response to wavelengths </li></ul><ul><li>Color is determined by an absorption certain wavelengths </li></ul><ul><li>Wavelengths </li></ul><ul><ul><li>Short  violet </li></ul></ul><ul><ul><li>Midlength  green, blue, yellow </li></ul></ul><ul><ul><li>Long  red </li></ul></ul><ul><li>Average person can discriminate about two million different colors </li></ul><ul><li>Photoreceptors </li></ul><ul><ul><li>Rods—black, white, gray (125 million) </li></ul></ul><ul><ul><li>Cones—colors (7 million </li></ul></ul>
  15. 15. Signal Detection Theory
  16. 16. Signal Detection Theory <ul><li>Decision making when uncertain involves </li></ul><ul><ul><li>Information acquisition </li></ul></ul><ul><ul><li>Criterion </li></ul></ul><ul><li>Factors that shape this decision making process: </li></ul><ul><ul><li>Expectations (of observer) </li></ul></ul><ul><ul><li>Rewards/costs associated with detecting/not detecting </li></ul></ul>
  17. 17. Factors Affecting Perception <ul><li>Attention </li></ul><ul><ul><li>Selective attention </li></ul></ul><ul><ul><li>Cocktail party effect </li></ul></ul><ul><ul><li>Novelty, size, color, movement </li></ul></ul><ul><li>Stroop Effect </li></ul><ul><ul><li>Reading is highly practiced, automatic activity </li></ul></ul><ul><ul><li>Bottom-up processing (stimulus-driven) </li></ul></ul><ul><li>Sensory Adaptation </li></ul>
  18. 18. Stroop Effect
  19. 19. Perceptual Processing <ul><li>Bottom-up Processing </li></ul><ul><ul><li>Processing of sensory info as it enters the receptors and travels to the brain </li></ul></ul><ul><ul><ul><li>Face-value interpretation </li></ul></ul></ul><ul><ul><li>Initiated by sensory input </li></ul></ul><ul><ul><li>Sensation  Perception </li></ul></ul><ul><li>Top-Down Processing </li></ul><ul><ul><li>Uses existing information (learning history) to interpret sensory information </li></ul></ul><ul><ul><li>Initiated by cognitive processing </li></ul></ul><ul><ul><li>Perception  Sensation </li></ul></ul>
  20. 20. Perceptual Constancy <ul><li>Perceptual Constancy: The tendency to perceive objects as relatively stable despite continually changing sensory information. </li></ul><ul><li>Examples: </li></ul><ul><ul><li>Shape, size, color, brightness </li></ul></ul><ul><ul><li>Varying distances, lighting conditions, angles </li></ul></ul>
  21. 21. Perceptual Constancy <ul><li>Size Constancy: </li></ul><ul><ul><li>Tendency to perceive objects as same size stable in size even if viewed from a distance </li></ul></ul>
  22. 22. Perceptual Constancy <ul><li>Shape Constancy: </li></ul><ul><ul><li>Tendency to perceive an object as the same shape no matter from what angle it is viewed. </li></ul></ul>
  23. 23. The Mueller-Lyer Illusion Illusions <ul><li>Depending on the direction of the arrow </li></ul><ul><ul><li>Inward or outward </li></ul></ul><ul><ul><li>Two equal length lines </li></ul></ul><ul><ul><li>One appears longer </li></ul></ul>
  24. 24. The Visual Cliff <ul><li>Experiment to test depth perception in infants </li></ul><ul><li>Found that infants early on could perceive depth </li></ul><ul><ul><li>Older infants would not crawl on “deep” side </li></ul></ul><ul><ul><li>Younger infants showed physiological changes </li></ul></ul>
  25. 25. Form Perception <ul><li>The process by which sensations are organized into meaningful shapes and patterns. </li></ul><ul><ul><li>The figure-and-ground principle </li></ul></ul><ul><ul><ul><li>brain organizes sensory input into: </li></ul></ul></ul><ul><ul><ul><ul><li>a figure (the center of attention) </li></ul></ul></ul></ul><ul><ul><ul><ul><li>ground (the background) </li></ul></ul></ul></ul><ul><ul><li>Rubin’s characteristics </li></ul></ul><ul><ul><ul><li>“ Thinglike” </li></ul></ul></ul><ul><ul><ul><li>In front of ground </li></ul></ul></ul><ul><ul><ul><li>Dominates, more memorable </li></ul></ul></ul>
  26. 26. Laws of Grouping <ul><ul><li>Similarity- Group together stimuli that are similar </li></ul></ul><ul><ul><li>Proximity-Group together stimuli that are together </li></ul></ul><ul><ul><li>Continuity-Perception of contours or straight lines as continuous </li></ul></ul><ul><ul><li>Closure- Tendency to close figures gaps in a figure and perceive it as whole. </li></ul></ul>
  27. 27. Laws of Grouping: Demos
  28. 28. The Nature of Consciousness <ul><li>What is consciousness? </li></ul><ul><ul><li>Our awareness of external events and internal sensations which occurs under conditions of arousal </li></ul></ul>
  29. 29. Levels of Awareness
  30. 30. Levels of Awareness <ul><li>Higher-Level Consciousness </li></ul><ul><ul><li>Controlled processes </li></ul></ul><ul><li>Lower-Level Consciousness </li></ul><ul><ul><li>Automatic processes </li></ul></ul><ul><ul><li>Daydreaming </li></ul></ul><ul><li>Subconscious Awareness </li></ul><ul><ul><li>Parallel processing </li></ul></ul><ul><li>Sleep and Dreams </li></ul><ul><ul><li>Low levels of consciousness </li></ul></ul><ul><li>No Awareness </li></ul><ul><ul><li>Unconscious thought (Freud) </li></ul></ul><ul><ul><li>Non-conscious processes </li></ul></ul>
  31. 31. Sleep: Biological Rhythms <ul><li>Rhythms controlled by biological clocks </li></ul><ul><ul><li>Annual or seasonal </li></ul></ul><ul><ul><li>28-day cycles/24-hour cycles </li></ul></ul><ul><li>Circadian Rhythms </li></ul><ul><ul><li>Desynchronizing the clock </li></ul></ul><ul><ul><ul><li>Jet lag </li></ul></ul></ul><ul><ul><ul><li>Shift-work problems </li></ul></ul></ul><ul><ul><ul><li>Insomnia </li></ul></ul></ul><ul><ul><li>Resetting the clock </li></ul></ul><ul><ul><ul><li>Bright light </li></ul></ul></ul><ul><ul><ul><li>Melatonin </li></ul></ul></ul>
  32. 32. Why Do We Sleep? <ul><li>Benefits of Sleep </li></ul><ul><ul><li>Important for physical and mental functioning </li></ul></ul><ul><li>Restorative Function </li></ul><ul><li>Adaptive Evolutionary Function </li></ul><ul><li>Growth and Development </li></ul><ul><li>Memory </li></ul>
  33. 33. Sleep Deprivation <ul><li>Chronic sleep deprivation results in… </li></ul><ul><ul><li>Decreased alertness and cognitive performance </li></ul></ul><ul><ul><li>Inability to sustain attention </li></ul></ul><ul><ul><li>Less complex brain activity </li></ul></ul><ul><ul><li>Adverse effects on decision making </li></ul></ul><ul><li>Research indicates we should get at least 8 hours of sleep each night! </li></ul>
  34. 34. Stages of Sleep <ul><li>EEG measures electrical activity in the brain </li></ul><ul><ul><li>Awake </li></ul></ul><ul><ul><li>Stage 1: light sleep </li></ul></ul><ul><ul><li>Stage 2: light sleep </li></ul></ul><ul><ul><ul><li>Sleep spindles </li></ul></ul></ul><ul><ul><li>Stage 3: deep sleep </li></ul></ul><ul><ul><li>Stage 4: deep sleep </li></ul></ul><ul><ul><ul><li>Difficult to wake sleepers </li></ul></ul></ul><ul><ul><li>REM sleep </li></ul></ul>
  35. 35. Stages of Sleep
  36. 36. REM Sleep <ul><li>Rapid-Eye-Movement Sleep = REM sleep </li></ul><ul><ul><li>Rapid eye movement; dreaming </li></ul></ul><ul><li>Stage 1-4: Non-REM Sleep </li></ul><ul><ul><li>Lack of rapid eye movement; little dreaming </li></ul></ul><ul><li>Dreams: Non-REM versus REM Sleep </li></ul><ul><li>Developmental Changes in REM Sleep </li></ul>
  37. 37. Sleep Cycles <ul><li>90-100 minutes per cycle </li></ul><ul><li>Sleep patterns change during the night. </li></ul><ul><li>Typical night </li></ul><ul><ul><li>60% - Stages 1 & 2 sleep </li></ul></ul><ul><ul><li>20% - Stages 3 & 4 sleep </li></ul></ul><ul><ul><li>20% - REM sleep </li></ul></ul>
  38. 38. Sleep Disorders <ul><li>Insomnia </li></ul><ul><li>Sleepwalking, Sleep Talking, Sleep Eating </li></ul><ul><li>Nightmares versus Night Terrors </li></ul><ul><li>Narcolepsy </li></ul><ul><li>Sleep Apnea </li></ul>
  39. 39. Hypnosis <ul><li>Hypnosis marked by </li></ul><ul><ul><li>Altered attention and awareness </li></ul></ul><ul><ul><li>Unusual receptiveness to suggestions </li></ul></ul><ul><li>Four Steps in Hypnosis </li></ul><ul><ul><li>Distractions are minimized </li></ul></ul><ul><ul><li>Told to concentrate on something specific </li></ul></ul><ul><ul><li>Told what to expect </li></ul></ul><ul><ul><li>Suggest events or feelings sure to occur </li></ul></ul>
  40. 40. Psychoactive Drugs <ul><li>Various substances alter consciousness, modify perceptions, and change moods </li></ul><ul><li>Why do people take drugs? </li></ul><ul><li>Continued use can lead to… </li></ul><ul><ul><li>Tolerance </li></ul></ul><ul><ul><li>Physical dependence and withdrawal </li></ul></ul><ul><ul><li>Psychological dependence </li></ul></ul><ul><ul><li>Addiction </li></ul></ul>
  41. 41. Critical Controversy <ul><li>Medicinal uses for psychedelic drugs? </li></ul><ul><li>LSD </li></ul><ul><li>Medical Marijuana </li></ul><ul><li>Psychedelic Drugs, Insight, and Creativity </li></ul>

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