Approaches to Perception Indirect Perception

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Approaches to Perception - Indirect Perception

• PS2009/10 Lecture 4

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Sources of Information

• Sensory Input
• Past Knowledge

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Questions

• How do they influence Perception?
• What is the relative importance of each source?

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Approaches

• Indirect or Constructive Approach
• Direct or Ecological Approach

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Indirect Approach

• Bruner (1957)
• Neisser (1967)
• Gregory (1972)

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Much as the information channels of instruments,
such as radio telescopes, transmit signals which
are processed according to various assumptions to
give useful data, so neural signals are processed
to give data for perception. To understand
perception, the signal codes and the stored
knowledge or assumptions use for deriving these
hypotheses need to be discovered Gregory
(1980)
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• Perception is an active process
• Perception is not directly given by the stimulus
  input, but is the end product of the interaction
  between the stimulus, expectations, hypotheses,
  and the knowledge that the perceiver brings to
  the situation.

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Ambiguous Figures
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Figure-Ground Reversals
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The Necker cube
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Muller-Lyre Illusion
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Ponzo Illusion
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Neisser (1969)

• Visual cognition, then deals with the process by
  which a perceived, remembered, and thought about
  world is brought into being from as unpromising a
  beginning as the retinal patterns.

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Indirect Perception

• Perceivers SEE retinal images
• Retinal images are snapshots of the environment
• Perceptual stimuli are discrete samples

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Perception of Motion

• Motion needs to be inferred from the snapshots of
  the environment
• Representational Momentum

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Evaluation of Perception as an indirect process

• Perception is fast AND accurate
• Are illusions a good way of testing the
  perceptual system?
• What hypotheses should be formed?
• How does information get into the system in the
  first place?

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Ames Room
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Figure Ground Distinctions (Von Sneden, 1960)