Approaches to Perception Direct Perception 2

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Approaches to Perception - Direct Perception 2

• PS2009/10 Lecture 6

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Perception as a Direct Process

• Information about
• Information for

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Affordances

• Affordances are the acts or behaviours permitted
  by objects events or places.
• Chairs afford sitting, objects with handles
  afford grasping, etc.

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Toye (1986)

• 13 metal stakes each of 1.5m in height with a
  letter at the top of each.
• 11 stakes set at random on a grass field 21m in
  diameter.
• 2 stakes at the perimeter

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Toye (1986) cont.

• Relative judgement task
• absolute judgement task
• draw a map of the layout of the stakes
• Participants did this twice from 2 different
  positions 90 degree apart.

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Toye (1986) cont.

• Indirect approach
• height and breadth are retinal properties BUT
  depth is calculated from cues such as stereopsis,
  height in the visual field etc.
• judgements from two positions should be
  different.
• Direct approach
• layout given directly by the optic array
• judgements from two positions should be the same.

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Shepherd Metzler (1971)

• Metal Rotation Task - time taken to decide if the
  two shapes are the same is a function of the
  angular rotation of the objects

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• Currently available sensory input (direct)
• relevant past knowledge (indirect)
• how do the influence perception?
• What is the relative contribution of each source
  of information?

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Perceptual Cycle (Neisser, 1976)