PSY101

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PSY101

• Sensation perception, Lecture 2
• the hand-out is the same as Monday
• if you havent got one I have a few with me today
  and it is also available on MOLE

Question given what you learnt on Monday, why
do pirates wear eye-patches?
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Summary so far

• Perception is a problem
• Psychophysics measuring the interface between
  the physical and mental
• The biology of transduction
• Adaptation Contrast active processing
• feature detectors

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Motion is a primitive
go waterfall video!
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• An aftereffect adaptation
• continous input is uninformative,
• our brain is interested in variation
• Motion registered directly,
• not computed from location and time
• Interocular transfer effect,
• proves its happening cortically
• storage
• proves it is designed in (cf fatigue)

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Perception is passive sensing
Perception is an active process
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Look, Proof!!
This is some text in the middle of the screen,
shake your head from side to side and youll
still be able to read it, thanks to the
Vestibular-Ocular Reflex which is mediated by the
cerebellum. But same relative motion from
external source.
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Perception is a problem
Perception is a cognitive problem
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Perception as problem solving
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image or interpretation?
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How is a perceptual problem solved?

• Assumptions and Cues are combined to make a best
  guess at what it is were seeing
• Cues features of the image that give clues as to
  the nature of the stimulus.
• Assumptions expectations about what we will see
  or what different cues mean

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Seeing Depth

• Objects have depth, images dont
• Depth/Distance information must be recovered
  using depth cues
• Binocular cues

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binocular disparity

• The images in the two eyes are more different for
  closer objects
• just try looking at your nose

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monocular cues

• interposition / occlusion

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• texture cues

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linear perspective
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http//users.skynet.be/J.Beever/
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shape from shading
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light!
shadows
shadows
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What happens if you stand on your head and look
at this?
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So far

• Perception as a problem
• Depth cues

Questions?