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					       Sensation & Perception
• Q1 Sensation is …..

• Requires coordination between receptors, neural
  pathways, sensory processing in the brain

• Perception is ……

• Psychophysics is
            Q2 - Processing
• Top-down…

• Bottom-up …

• Parallel/ serial ….
                Thresholds
• Q3 Absolute threshold - the intensity level
  at which a stimulus can be. ….

• Subliminal stimulation …

• Priming …..
   Signal detection theory – Q4
• Predicts ….

• Thresholds will …

• Tries to show why people respond …
• Q4 Difference threshold - the minimum change
  …

• This may vary depending on health, stress, etc
• Weber’s Law


• Why can’t you buy 63 watt light bulbs?
       Adaptation, habituation
• Q6 Sensory adaptation - decline in receptor
  activity …

• (it’s also true that your brain filters out
  sensory info you don’t need - reticular
  formation)
• Habituation - weakening of a …..
           Parts of the eye – Q7
•   Cornea
•   Iris
•   Pupil
•   Lens
•   Retina
•   Rods - 120 million - edge - fewer bipolars
•   Cones - 6 million at fovea - indiv bipolars
•   Bipolar cells
•   Ganglion cells
•   Optic nerve --- blind spot
             Transduction
• Q8 Transduction is …..



• The electromagnetic spectrum …

• Q9 - Frequency / amplitude – intensity/hue
         Q10 - Near and Far
• Near-sightedness



• Far-sightedness
From the optic nerve to the brain
• Optic nerve

• Crossover -

• Sensory switch…..

• Visual ….
Visual fields
Optical chiasm - Q11
      Color and detail - feature
             detection
• Only the cones respond to color
• Low ratio of cones to bipolar increases
  detail
• Q12 -Feature detection - individual neurons
  in visual cortex respond …

• Other neurons integrate features - face
  recognition
                Low light
• Cones do not work in low light - no color
  vision
• Rods have higher ratio of rods to bipolar
  cells - aids in concentrating response to low
  light
             Color vision
• Q13 - Young-Helmholtz trichromatic
  theory
• RGB ….

• Q14 - Color-blindness …
                  Q15
• Additive color mixing …




• Subtractive color mixing …
    Opponent process theory – Q15
•   See afterimage graphic
•   Neuron pairs ……
•   Some neurons turn on …..
•   When you stare at a green image for a while
    …
      Color constancy – Q16
• Why can you distinguish colors when
  wearing sunglasses?
          A little physics - Q17
•   Sound is waves of air striking our ears
•   Height of waves = amplitude =
•   Length of waves = frequency =
•   Complexity =
•   Decibel scale measures loudness
•   Log scale: 20 = 10 x 10 30 = 20 x 10,
    WHY?
           Parts of the ear
• Q18 See the diagram
       Perceiving pitch - Q19
• Helmholtz’s place theory - different sound
  waves stimulate hair cells …

• This works for higher pitched sounds
     Low pitched sounds – Q19
• Frequency theory says the entire basilar
  membrane…

• The brain interprets this as pitch.

• Works for low pitched sounds
           Perceiving pitch
• Some combination of place and frequency
  theory works for all sounds
        Locating sound – Q20
• Just as two eyes help us locate objects with
  our vision …
• Sounds strike each ear at different …

• Differences are extremely small
         Hearing loss – Q21
• Sensorineural …



• Conduction hearing loss …

• Implants
              Touch – Q22
• The four senses of touch …



• Are they distinct?
               Pain – Q23
• Pain is ……



• Gate control theory says …
               Taste – Q24
• The 5 tastes are ….

• Are there really 5 tastes?



• Other influences on what we taste …
              Smell – Q25
• Smell is different …



• Processing smells ….
         Body position – Q26
• Kinesthesis ….

• Vestibular sense …

• Vestibular sacs and semicircular canals
  contain fluid and hair cells that react when
  we move. Hair cells send message to brain
                  Review
• Light energy transduced in retina - rods,
  cones – sent to bipolar cells, ganglions to
  optic nerve to visual field crossover at optic
  chiasm to thalamus for more color
  processing to visual cortex for feature
  detection to temporal and frontal lobes for
  integration which is influenced by context,
  assumptions and expectations
     Selective attention – Q27
• An animated Necker cube

• Cocktail party effect

• Q4 Inattentional blindness –
  http://viscog.beckman.illinois.edu/flashmovie/
    15.php
        Muller-Lyer
• Q28
              Organization
• Q29 Gestalt principles of perception



• Gestalt therapy
Figure and ground
               Grouping
• Proximity

• Similarity

• Continuity
              Grouping
• Connectedness



• Closure
           Depth perception
• Q30 Innate ability - Gibson & visual cliff
• http://www.vimeo.com/77934



• Q31 Binocular cues
  – Retinal …
  – Conver…
            Depth perception
• Q32 Monocular cues
  – Relative size

  – Interposition

  – Relative clarity
          Monocular cues
– Texture gradient

– Relative height

– Relative motion

– Light / shadow
     Constancies & Other Stuff
• Q33 Phi phenomenon
• Q34 Size - distance relationship

• Size / shape constancy
• Lightness constancy
            Set, expectancy
• Q35 – Perceptual set

• Context

• Expectancy

				
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