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Sensation & Perception

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Sensation & Perception

  1. 1. Sensation & Perception AP Psychology Mrs. VanCoughnett
  2. 2. Do you hear what I hear? <ul><li>Write the first thing you think of when you hear the following. </li></ul>
  3. 3. What’s the Difference? <ul><li>Sensation: detecting and encoding physical energy as neural signals </li></ul><ul><ul><li>aka: what you hear/see/touch/smell/taste </li></ul></ul><ul><li>Perception: selection, organization, and interpretation of our sensations; </li></ul><ul><ul><li>aka: what it all MEANS </li></ul></ul><ul><li>We transform sensations into perceptions </li></ul>
  4. 4. Creating Meaning <ul><li>Bottom-Up Processing: analysis of information incoming from sense receptors </li></ul><ul><ul><li>“ Bottom” = Stimulus </li></ul></ul><ul><li>Top-Down Processing: Drawing meaning from experience and expectations </li></ul><ul><ul><li>“ Top” = mental set in the brain </li></ul></ul>
  5. 5. How sensitive art thou? <ul><li>Absolute threshold: minimum stimulation needed to detect a stimulus 50% of the time </li></ul><ul><li>Difference threshold: minimum difference detected between 2 stimuli 50% of the time </li></ul><ul><ul><li>Aka: Just Noticeable Difference (JND) </li></ul></ul>
  6. 7. Laws Governing Detection <ul><li>Weber’s Law: to be perceived differently, stimulus must differ by a constant minimum percentage </li></ul><ul><li>Fechner’s Law: actual magnitude vs. perceived magnitude </li></ul><ul><li>Steven’s Power Law: estimation of magnitude </li></ul>
  7. 8. Change is GOOD <ul><li>All senses require CHANGE to FUNCTION </li></ul><ul><li>Sensory Adaptation: diminished sensitivity resulting from constant stimulation </li></ul><ul><li>Heightens sensitivity to important information </li></ul><ul><li>“ We perceive the world not exactly as it is, but as it is useful for us to perceive it.” </li></ul>
  8. 9. VISION: Light Energy <ul><li>Eyes see pulses of electromagnetic energy </li></ul>
  9. 10. VISION: Light Energy <ul><li>Wavelength: distance between wave peaks </li></ul><ul><li>Hue: experienced color (red, green, etc.) </li></ul><ul><li>Intensity: energy of light waves; influences brightness </li></ul>
  10. 11. VISION: The Retina <ul><li>Photoreceptors: light-sensitive cells that convert light energy to neural impulses </li></ul><ul><li>Rods: detect black, white, gray; peripheral & twilight vision </li></ul><ul><li>Cones: detect fine detail and color sensations; daylight & well-lit conditions </li></ul><ul><li>Optic Nerve: bundle of ganglion cell axons which carry information to the brain </li></ul><ul><li>Blind Spot: where the optic nerve leaves the eye </li></ul>
  11. 12. VISION: Blind Spot <ul><li>Blind spot </li></ul>
  12. 13. Vision Centers in the Brain <ul><li>Visual Cortex (in the Occipital Lobe) </li></ul><ul><ul><li>Turns 2D into 3D </li></ul></ul><ul><ul><li>Transforms neural impulses into visual sensations (color, images, patterns etc.) </li></ul></ul>
  13. 14. Color? <ul><li>Color is a sensation that is created by our brains </li></ul><ul><li>Wavelengths of visible light are transduced by photoreceptors in our retinas </li></ul><ul><li>We can create over 5 million different hues </li></ul>
  14. 15. Theories of Color <ul><li>Trichromatic Color Theory (Young & Von Helmholtz) </li></ul><ul><ul><li>Cones in retina sense red, green, and blue </li></ul></ul><ul><li>Opponent Process Theory (Hering) </li></ul><ul><ul><li>Process colors in complementary pairs </li></ul></ul><ul><ul><li>Seeing red means that the green photoreceptors are turned off </li></ul></ul><ul><ul><li>Negative Afterimages </li></ul></ul>
  15. 16. Color Blindness <ul><li>“ Color Weakness” </li></ul><ul><li>Lacking a chemical produced by the cones </li></ul><ul><li>Red/Green is most common </li></ul><ul><li>More common in males </li></ul><ul><li>The world through color blind eyes </li></ul>
  16. 17. Hearing: Audition <ul><li>Best hear frequencies in the range of human voice </li></ul><ul><li>Why?? </li></ul><ul><li>Detect important faint sounds (ex: child’s whimper) </li></ul><ul><ul><li>Signal Detection Theory** </li></ul></ul><ul><ul><ul><li>Our threshold for hearing depends on a variety of factors (ex: fatique, emotional distress, attention) </li></ul></ul></ul>
  17. 18. How do we hear? <ul><li>Frequency: the # of wavelengths that pass a point at a given time; determines pitch </li></ul><ul><li>Pitch: highness/lowness of tone </li></ul><ul><ul><li>Depends on frequency </li></ul></ul><ul><li>Sound waves  neural impulses in the brain </li></ul><ul><li>Waves vary by strength (amplitude) and length (frequency/pitch) </li></ul>
  18. 19. Physical Properties of Waves Short wavelength=high frequency (bluish colors, high-pitched sounds) Long wavelength=low frequency (reddish colors, low-pitched sounds) Great amplitude (bright colors, loud sounds) Small amplitude (dull colors, soft sounds)
  19. 20. How is sound measured? <ul><li>Decibels: unit of measure for sound energy </li></ul>
  20. 21. How safe is your iPod? 5 minutes 95% level 90 minutes per day 80% level 4.6 hours per day 70% level Safe listening time iPod sound level
  21. 23. Hearing Loss <ul><li>Conduction Hearing Loss </li></ul><ul><ul><li>Punctured ear drum, inner ear bones don’t vibrate </li></ul></ul><ul><li>Sensorineural Hearing Loss </li></ul><ul><ul><li>More common </li></ul></ul><ul><ul><li>Damage to cochlea or nerve fibers </li></ul></ul><ul><ul><li>Age, heredity, exposed to loud noise </li></ul></ul>
  22. 24. Touch: Kinesthetic Sense <ul><li>Essential to development </li></ul><ul><ul><li>Attachment, Harlow’s monkeys </li></ul></ul><ul><li>Mixture of 4 elements </li></ul><ul><ul><li>Pressure, warmth, cold, pain </li></ul></ul><ul><li>Why can’t you tickle yourself?? </li></ul><ul><li>Rubber Hand Illusion </li></ul><ul><li>Kinesthesis : sense of position and movement of your body parts </li></ul><ul><li>Vestibular Sense : position and movement of your head (balance) </li></ul>
  23. 25. Pain <ul><li>Why do we feel pain? </li></ul><ul><li>Melzack & Wall – Gate Control Theory </li></ul><ul><ul><li>theory that the spinal cord contains a neurological “gate” that blocks pain signals or allows them to pass on to the brain </li></ul></ul><ul><li>Can we control the pain? </li></ul><ul><ul><li>Distraction, phantom limb </li></ul></ul><ul><li>endorphins </li></ul>
  24. 26. Smell <ul><li>Olfaction : sense of smell </li></ul><ul><li>Chemical sense </li></ul><ul><li>Odors can evoke memory & emotion </li></ul><ul><li>Anosmia : Inability to smell </li></ul><ul><li>Smelling ability peaks in adulthood </li></ul><ul><li>Good or bad smells based on experience </li></ul>
  25. 27. Figure 12.5 The sense of smell Myers: Exploring Psychology, Sixth Edition in Modules Copyright © 2005 by Worth Publishers
  26. 28. The Other Senses: Taste <ul><li>200 + tastebuds </li></ul><ul><li>Receptors for: sweet, sour, salty, bitter, & umami </li></ul><ul><li>Taste receptors reproduce every 1-2 weeks </li></ul><ul><li>Decrease in taste sensitivity as age increases </li></ul><ul><li>Smoking and alcohol speed up process </li></ul><ul><li>Sensory interaction : one sense influences another </li></ul><ul><li>Smell+Texture+Taste=Flavor </li></ul>
  27. 29. Subliminal Messaging <ul><li>How does it work? </li></ul><ul><ul><li>Unconscious perception of stimuli </li></ul></ul><ul><ul><li>Suggestive powers </li></ul></ul><ul><li>Priming </li></ul><ul><ul><li>Good vs. bad scenes and faces </li></ul></ul><ul><li>Much of our information processing occurs automatically and outside of our conscious awareness. </li></ul>
  28. 31. Perception <ul><li>Gestalt Psychology: study of human tendency to organize pieces of information into meaningful wholes </li></ul>
  29. 32. Form Perception <ul><li>Figure-Ground: perceive an object (figure) as distinct from its surroundings (ground) </li></ul>
  30. 33. Grouping
  31. 34. Closure
  32. 36. Depth Perception: A 3-D World
  33. 37. How does 2-D become 3-D? <ul><li>Binocular Cues </li></ul><ul><ul><li>Retinal Disparity: the greater difference between objects viewed, the closer it is </li></ul></ul>
  34. 38. How does 2-D become 3-D? <ul><li>Monocular Cues </li></ul><ul><ul><li>Relative Size </li></ul></ul><ul><ul><li>Interposition: object blocking the view of another perceived as closer </li></ul></ul><ul><ul><li>Relative Height </li></ul></ul><ul><ul><li>Relative Motion (motion parallax) </li></ul></ul><ul><ul><li>Linear Perspective </li></ul></ul><ul><ul><li>Light & Shadow </li></ul></ul>
  35. 44. Motion Perception <ul><li>Rapid series of varying images </li></ul><ul><li>Phi phenomenon : illusion of movement created when two lights blink on and off in quick succession </li></ul>
  36. 45. Perceptual Constancy <ul><li>Perceiving objects as unchanging, even though our sensations of them have changed </li></ul><ul><li>Shape </li></ul><ul><li>Size </li></ul><ul><li>Distance </li></ul><ul><li>Lightness </li></ul>
  37. 50. The Nature/Nurture of Perception <ul><li>Does experience influence our perception of the world around us? </li></ul><ul><li>The blind have problems perceiving objects once their vision is restored due to lack of experience and neural connections </li></ul><ul><li>Critical Period : optimal time for sensory and perceptual development </li></ul>
  38. 51. Can our perceptions change? <ul><li>Perceptual adaptation : ability to adjust to changing perceptual conditions </li></ul><ul><ul><li>Ex: Looking at the world upside down </li></ul></ul>
  39. 52. Do Assumptions Effect Perception? <ul><li>Perceptual set : mental predisposition influencing what we perceive </li></ul><ul><li>Mary had a </li></ul><ul><li>a little lamb </li></ul><ul><li>Paris in the </li></ul><ul><li>the Springtime </li></ul>
  40. 53. Looking in Context <ul><li>Perception different between individuals due to differing schemas and context </li></ul><ul><li>“ Dye” vs. “die”; “attacks” vs. “a tax” </li></ul>
  41. 54. The Human Factor <ul><li>Human Factor Psychologists : design technology & environments to fit our perceptions </li></ul><ul><li>User-test products </li></ul>