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Pattern Recognition
 

Pattern Recognition

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    Pattern Recognition Pattern Recognition Presentation Transcript

    • Pattern Recognition
      Nick Lund
      Attention and Pattern Recognition
    • Introduction
      Pattern recognition has been defined as ‘the ability to abstract and integrate certain elements of a stimulus into an organised scheme for memory storage and retrieval’ (Solso,1998).
    • Features of pattern recognition
      Five principles(Solso,1998):
      1.Quickly and accurately.
      2.Recognise and classify unfamiliar objects.
      3.Accurately recognise shapes and objects from different angles.
    • Features of pattern recognition
      4.Identify patterns and objects even when partly hidden.
      5.Recognise patterns quickly,with ease,and with automaticity.
    • Features of pattern recognition
      Template matching theories
      Feature analysis
      Prototype theories
    • Top-down and bottom-up processing
      An examination of the theories of pattern recognition raises the question of whether pattern recognition involves top-down or bottom-up processing.
    • Bottom- up process
      Template matching theory
      Geons (Structural- description theory)
      Feature theory
      Prototype theory
    • Template matching theory
      External stumuli matches internal template
      Vast numbers of templates are stored
      Templates are created by experience
      E.x.: visit Russia
    • A
      A
      A
      A
      Problems:
      1) Only occurs when there’s a one-to-one match
      Payne and Wenger (1998)
    • 2) Where are all these templates stored?
      3) Slow process
      Ex.: recognize 1000-1500 letters a minute
      4) To recognize new variations of a pattern (Solso, 1998)
    • Geons (Structural- description theory)
      Biederman (1987)
      Limited number (24) of simple geometric shapes , or geons for us to analyse patterns.
      Ex.: mug v.s. bucket
    • Geons
    • Advantage:
      Recognize pattern from different angles
      Disadvantage:
      Can’t explain why we recognize a particular chair.
      Ex.: My face v.s. my friend’s face
    • Feature theory
      Patterns are recognized by analysis of the individual features of the pattern.
      Ex.: MANGO
      M
      A
    • Four stages of pattern recognition
      Image demons: record the image and pass it
      Feature demons: analyse the image for specific feature
      Ex.:
      Pandemonium model (Selfridge, 1959)
    • Cognitive demons: detect the present feature and shout
      Decision demons: pick up the loudest feature
    • Advantage:
      More flexible than template theory
      Ex.: A , regardless of size, shape or orientation
      Neisser:
      M -> N H M V -> longer RT
      (more distracter)
      M -> O M Q G -> shorter RT
    • Disadvantage:
      Fail to account for the effects of context and expectations
      Ex.:
      Two experiments which can’t explain feature theory
      Fail to detect “t” in “the” (Healy)
      Teacup, eyebrow -> cup, eye ; eac, ebr (Inhoff and Topolski)
    • Eysenck and Keane:
      • How can we recognize patterns when their features are hidden from view?
      Relationship between the features
      • Ex. : T v.s. L
    • The biology of feature theory
      Hubel and Wiesel (1959)
      In visual cortex:
      Simple cells: particular orientation, specific location
      complex cells: lines or edges, in all visual field
      Hypercomplex cells: length and angles, combination of features
    • Disadvantage:
      Some questioned the existence of hypercomlex cells
      How specialized they need to be?
      Run out of cells
    • Prototype theory
      External stimuli matches with internal abstract prototype
      Ex.: R, compare to all other “R”s
      Solso(1998): two theoretical models
      Central-tendency model:
      • The average, mean
      Attribute-frequency model:
      • Most common combination, mode
    • Advantage:
      More “economical” than template theory
      Don’t need templates for every shape, size, orientation
      Explain the speed of recognition of letters, words and patterns / novel stimuli
    • Disadvantage:
      can’t explain the effect of context (Eysenck, 1993)
      old woman v.s. young lady
      B, R, P have similar prototype
    • Top-down processing
      Word superiority effect
      Rat-Man demonstration
    • Rat-Man demonstration
    • Rat-Man demonstration
    • Rat-Man demonstration
    • The effect of context
    • Summary
      Pattern Recognition
      Theories
      Template matching
      Feature analysis
      Prototype
      Central-tendency
      Attribute- frequency
    • Summary
      Word superiority effect
      Rat-Man demonstration
      Pandemonium model
      Geons
      Top-down processing
      Bottom- up processing
    • THE END