Units 14+15


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Units 14+15

  1. 1. Sensation and Perception
  2. 2. Sensation <ul><li>Process by which body gathers information about environment </li></ul><ul><li>Connects us to the world </li></ul><ul><li>Sensation generally occurs in the sense organs </li></ul><ul><ul><li> – vision (detects light waves) </li></ul></ul><ul><ul><li>– audition (sense of hearing) </li></ul></ul><ul><ul><li> – olifaction (sense of smell) </li></ul></ul><ul><ul><li>– gustation (sense of taste) </li></ul></ul><ul><ul><li>– cutaneous (sense of touch) </li></ul></ul>
  3. 3. Perception <ul><li>Process by which the brain organizes and interprets sensory information (“sensation PLUS perception”) </li></ul><ul><li>Perception occurs in the brain </li></ul><ul><li>3 basic principles </li></ul><ul><ul><ul><li>adaptive </li></ul></ul></ul><ul><ul><ul><li>active </li></ul></ul></ul><ul><ul><ul><li>no one-on-one correspondence between physical and psychological reality </li></ul></ul></ul>
  4. 8. Perception <ul><li>Top-down processing </li></ul><ul><ul><ul><li>“ Conceptually-driven processing” </li></ul></ul></ul><ul><ul><ul><li>Take information already existing in the mind to interpret environment </li></ul></ul></ul><ul><li>Bottom-up processing </li></ul><ul><ul><ul><li>“ Data-driven processing” </li></ul></ul></ul><ul><ul><ul><li>Take stimuli from the environment and make attempts to determine its meaning </li></ul></ul></ul>
  5. 9. Sensation <ul><li>Sensory receptors – Eyes, ears, nose, etc. detect physical energy (light/sound/smell) </li></ul><ul><li>Transduction – Translates physical energy into neural signals </li></ul><ul><li>Absolute threshold – Each system’s minimal amount of energy required to activate it </li></ul><ul><li>Difference threshold – Each system’s minimal amount of energy required to detect change from one level of stimulus to another </li></ul><ul><li> – Just-noticeable difference (Weber’s Law) </li></ul>
  6. 10. <ul><li>In this experiment, say the color of the word (not what the word says) </li></ul><ul><li>Example: For the word RED you should say “Red”. For the word RED you should say “Yellow“ </li></ul><ul><li>As soon as the words appear on your screen, read the list as fast as you can </li></ul>Stroop Effect
  7. 13. Stroop Effect <ul><li>In this experiment, look at a picture of an animal and say the name of the animal. Do NOT read the word placed on the picture. </li></ul><ul><li>For example: You should say &quot;Cow&quot; because the animal in the picture is a cow. </li></ul><ul><li>You should sat “Cat” because the animal in the picture is a cat. </li></ul>
  8. 16. Vision <ul><li>Allows for the detection of movement, light, depth perception </li></ul><ul><li>Transduction – impulses from optic nerve carry visual information from retina to optic chiasm; neural messages then travel to thalamus and into the visual cortex </li></ul>
  9. 17. Vision <ul><li>Motion perception </li></ul><ul><ul><ul><li>Rods in retina sensitive to motion activate neurons in the visual cortex </li></ul></ul></ul><ul><ul><ul><li>2 systems for processing movement </li></ul></ul></ul><ul><ul><ul><ul><ul><li>Eye stationary as object moves </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Eye moves to maintain object at same place on the retina </li></ul></ul></ul></ul></ul>
  10. 20. Vision <ul><li>Photoreceptors </li></ul><ul><ul><ul><li>Cones </li></ul></ul></ul><ul><li>- Highest concentration in the fovea </li></ul><ul><li>- Require light to be activated </li></ul><ul><li>- Less numerous (7+ million) </li></ul><ul><li>- Color vision/trichromatic theory (“photopic vision”) </li></ul><ul><li>- High visual acuity </li></ul><ul><li>- Low sensitivity </li></ul><ul><ul><ul><li>Rods </li></ul></ul></ul><ul><ul><ul><ul><ul><li>Highest concentration in the retina </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>More numerous (120+ million) </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Night vision (“scoptic vision”) </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Low visual acuity </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>High sensitivity (esp. motion detection) </li></ul></ul></ul></ul></ul>
  11. 24. Vision <ul><li>Color blindness </li></ul><ul><ul><ul><li>Inability to distinguish colors </li></ul></ul></ul><ul><ul><ul><li>“ Disease” is linked to the X chromosome, thus males more likely than females to be color blind </li></ul></ul></ul><ul><ul><ul><li>Most common condition is red-green color blindness (difficulty distinguishing red and green) </li></ul></ul></ul>
  12. 29. Hearing <ul><li>Transduction </li></ul><ul><ul><ul><li>Outer ear collects physical stimuli (sound waves) </li></ul></ul></ul><ul><ul><ul><li>Middle ear converts waves of air pressure into movements </li></ul></ul></ul><ul><ul><ul><li>Inner ear carries movements via waves of fluid (in ear drum) that generate neural signals </li></ul></ul></ul><ul><ul><ul><li>Signals sent to thalamus then to temporal lobe </li></ul></ul></ul>
  13. 31. Hearing <ul><li>Volume – “loudness” determined by the height of sound wave (amplitude) </li></ul><ul><li>Pitch – refers to the frequency of the sound wave (low B flat/high C tone) </li></ul>
  14. 32. Touch <ul><li>Protects body from injury, helps identify objects, maintain body temperature </li></ul><ul><li>4 basic skin sensors (heat, cold, pain, pressure) </li></ul><ul><li>Touch sensations differ throughout the body </li></ul><ul><li>Transduction </li></ul><ul><ul><ul><li>Sensory neurons in skin send impulses to spinal cord or communicate with interneurons (that in turn stimulate motor neurons) </li></ul></ul></ul>
  15. 34. Taste <ul><li>Refers to four basic tastes (sweet, sour, salty, bitter) and protects us from injecting toxic substances </li></ul><ul><li>Transduction </li></ul><ul><ul><ul><li>Occurs in the taste buds </li></ul></ul></ul><ul><ul><ul><li>Physical stimulus (soluble chemicals) activate taste receptor neurons which carry information to thalamus and primary cortex to help identify taste </li></ul></ul></ul>
  16. 35. Smell <ul><li>Detect danger (e.g., smoke, spoiled food) and/or recognize familiar odors </li></ul><ul><li>Transduction </li></ul><ul><ul><ul><li>Physical stimulus (air molecules) enter nasal cavity through nose </li></ul></ul></ul><ul><ul><ul><li>Receptors in olfactory epithelium pass information through the olfactory bulb to the primary cortex, which then connects with thalamus and amygdala </li></ul></ul></ul>