Theories of Pattern Recognition

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Theories of Pattern Recognition

• PS2009/10 Lecture 10

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Feature Theories
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Evidence for Feature Theories

• Neurological evidence
• Behavioural evidence

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Lettvin, Maturana, McCulloch Pitts (1959)

• Edge Detectors
• Moving Edge Detectors
• Dimming Detectors
• Convex Edge Detectors

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Receptive fields in the visual cortex
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Hubel and Wiesel (1959)

• Simple Cell
• Complex Cells
• Hypercomplex Cells
• see also Gross et al (1972)

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Behavioural Evidence

• Stopped Images
• Confusability Studies

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Stopped Images Pritchard, Heron, Hebb (1960)
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Confusability Studies
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Neisser (1964)
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Kinney, Marsatta, Showman (1966)
Participants briefly presented with letter
G Errors made in identification C - 21
participants O - 6 B - 1 9 - 1
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Problems with Feature Theories

• Do not take account of context
• difficult to apply to complex stimuli
• Do not take account of structural relationships
• Analysis does not always begin with simplest
  features
• Neuropsychological evidence is not as clear as
  originally thought
• Features not all treated in the same way

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Context
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Context
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Context
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Complex stimuli
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Structural Relationships
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Navon (1977)
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Feature Detectors?
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