Sensation and Perception

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Sensation and Perception

• Sensations take it in
• Perception what we do with it

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Vision

• The eye receives light waves and converts energy
  into neural impulses by a process called
  Transduction.

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http//www.exploratorium.edu/learning_studio/cow_e
ye/video_big_all.html
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• Wavelength hue
• Amplitude brightness

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Blue Man Group

• http//www.youtube.com/watch?vW-yLfm5HsHc

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Rods and Cones are the visual receivers

• Rods process black and white.
• denser on the outside, active in dim light,
• Cones processes color
• clustered mainly in the center of the eyes
  focus, the fovea
• Needs bright light to function
• turns off in dim light
• processes with more sharpness than rods.

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Color vision

• Young-Helmholtz Trichromatic Theory there are
  three types of cones each sensitive to the
  primary colors (red, blue, green).
• The brain mixes the sensations from those to
  create all the perceived colors we see. Color
  blindness people lack receptors for one of the
  three.

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• Two theories within a theory do we add or
  subtract? Depends on the situation
• Coloring book additive
• Theater lighting - subtractive

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Problems

• If the lens or cornea is distorted in relation to
  the eye then it effects the acuity or sharpness
  of the image seen.
• One is said to be either nearsighted or
  farsighted when this occurs.

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The Process

• Light energy hits the rod or cone which creates a
  photochemical reaction
• Photochemical reaction creates an electrical
  impulse sent to bipolar cells, which funnel the
  electricity to ganglion cells
• Ganglion cells, whose combined axons create the
  Optic Nerve,
• which leads to the brain. The spot where the
  Optic nerve leaves the eye is a blind spot.

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Color Vision

• Opponent process theory states that some neurons
  receive one color and are turned off by another.
• For instance, a neuron can detect red, but
  another is turned off by it, so you cant see
  shades of certain combinations reddish green.
  This theory is used to explain afterimages, where
  you wear out the response in one neuron for one
  color and then can only see the opposing color
  when staring at a white board, until the neuron
  replenishes.

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http//www.grand-illusions.com/opticalillusions/am
azing_dots/
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Visual Processing

• Feature detectors Separate neurons and neural
  networks in the brain which are sensitive to
  specific stimuli, angles, lines, edges, shapes or
  movements
• allowing the brain to differentiate individual
  objects or movements to concentrate on.

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Where feature detectors detect.