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Sensation and Perception

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Sensation and perception
Sensation and perception
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Sensation and Perception

  1. 1. SENSATION AND PERCEPTION
  2. 2. Sensation & Perception • How Does Stimulation Become Sensation? • How Are the Senses Alike? How Are They Different? • What Is the Relationship between Sensation and Perception?
  3. 3. How Does Stimulation Become Sensation? • Transduction: Changing Stimulation to Sensation • Thresholds: The Boundaries of Sensation Signal Detection Theory
  4. 4. Transduction • Transforming signals into neural impulses. • Information goes from the senses to the thalamus , then to the various areas in the brain.
  5. 5. Sensory Adaptation • Decreased responsiveness to stimuli due to constant stimulation. Do you feel your underwear all day?
  6. 6. Cocktail-party phenomenon • The cocktail party effect describes the ability to focus one's listening attention on a single talker among a mixture of conversations and background noises, ignoring other conversations. • Form of selective attention.
  7. 7. How Are the Senses Alike? How Are They Different? • Vision: How the Nervous System Processes Light • Hearing: If a Tree Falls in the Forest . . . How the Other Senses Are Like Vision and • Hearing Synesthesia: Sensations across the Senses Energy Senses Chemical Senses
  8. 8. Energy v. Chemical senses Energy Senses Chemical Senses
  9. 9. Vision
  10. 10. Step One: Gathering Light The Eye Light enters through a narrow opening Cornea – transparent eye cover Iris – muscle; colored part of the eye Pupil – opening in the iris • Sensitive to light and emotion
  11. 11. Step Two: Within the Eye
  12. 12. Step Three: Transduction
  13. 13. Step Four: In the Brain • Feature detectors- – Hubel and Wiesel – groups of neurons in the visual cortex respond to different types of visual images.
  14. 14. Feature Detectors
  15. 15. Theories of color vision: Explain our ability to distinguish between colors Trichromatic theory •Young-Helmholtz: three types of receptors (cones) all others variations Opponent- process theory •Hering: three types of bipolar receptors •Supported by negative afterimages Thought to work together: •Thricomatic: Cones •Opponent- Process: Thalamus Color Vision
  16. 16. Trichromatic Theory Three types of cones: • Red • Blue • Green • These three types of cones can make millions of combinations of colors. • Does not explain afterimages or color blindness well.
  17. 17. Opponent-Process theory The sensory receptors come in pairs. • Red/Green • Yellow/Blue • Black/White • If one color is stimulated, the other is inhibited.
  18. 18. Plates from a Test for Color Blindness
  19. 19. Principles of Visual Perception • Process used to organize sensory impressions caused by the light that strikes our eyes • Sensation is a mechanical process • Perception is an active process – Involves experience, expectations and motivations
  20. 20. Perceptual Organization • Figure – Ground Perception – Ambiguous, unstable figures, we shift back & forth
  21. 21. 1. Visual Perception • Process used to organize sensory impressions caused by the light that strikes our eyes • Sensation is a mechanical process • Perception is an active process – Involves experience, expectations and motivations
  22. 22. 1. Visual Perception • Process used to organize sensory impressions caused by the light that strikes our eyes • Sensation is a mechanical process • Perception is an active process – Involves experience, expectations and motivations
  23. 23. Gestalt Rules for Perceptual Organization
  24. 24. Perception of Motion • Visual perception of motion is based on change of position relative to other objects • Illusions of movement – Stroboscopic motion (class discussion, how do we know that a train moves?) • Induced Motion: http://psychlab1.hanover.edu/Classes/Sensati on/induced/index.html
  25. 25. • Binocular Cues – Retinal disparity – Convergence • Monocular cues Depth Perception
  26. 26. Constancy • Acquired through experience; creates stability – Size Constancy – Color Constancy – Brightness Constancy – Shape Constancy
  27. 27. Faces • http://www.michaelbach.de/ot/fcs_hollow- face/index.html
  28. 28. Lightness Perception • http://persci.mit.edu/demos/gaz/main- frameset.html
  29. 29. Turning Tables • http://www.michaelbach.de/ot/sze_shepardT ables/index.html
  30. 30. Perception and Culture
  31. 31. Hearing: Transduction in the Ear
  32. 32. Pitch Theories • Different hairs vibrate in the cochlea when they different pitches. • So some hairs vibrate when they hear high and other vibrate when they hear low pitches. Place Theory • The height of the wave gives us the amplitude of the sound. • The frequency of the wave gives us the pitch if the sound. Frequency Theory
  33. 33. Deafness • Conduction Deafness – Something goes wrong with the sound and the vibration on the way to the cochlea. • Nerve (sensorineural) Deafness
  34. 34. Touch • Cutaneous Senses: Receptors located in our skin. • Dermatomes
  35. 35. • Gate control theory: sensations are mediated by neural gates in the spinal cord that lalow them to continue to brain Pain
  36. 36. Taste • We have bumps on our tongue called papillae. • Taste buds are located on the papillae (they are actually all over the mouth). • Sweet, salty, sour and bitter.
  37. 37. • Primary olfactory cortex • Orbitofrontal cortex • Amygdala Olfaction
  38. 38. BODY POSITION SENSES
  39. 39. Vestibular Sense • Tells us where our body is oriented in space. • Our sense of balance. • Located in our semicircular canals in our ears.
  40. 40. Kinesthetic Sense • Tells us where our body parts are. • Receptors located in our muscles and joints.
  41. 41. What Is the Relationship between Sensation and Perception? • Perceptual Processing: Finding Meaning in Sensation • Perceptual Ambiguity and Distortion Theoretical Explanations for Perception Seeing and Believing
  42. 42. Perception • We see things • How do our minds make our worlds?
  43. 43. Thresholds Absolute threshold: • The absolute threshold is the smallest amount of stimulus we can detect. Difference threshold: • How much does a stimulus need to change before we notice the difference?
  44. 44. Weber’s Law
  45. 45. Stepping Feet • http://www.michaelbach.de/ot/mot- feetLin/index.html

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