Pattern Recognition


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Pattern Recognition

  1. 1. Pattern Recognition<br />Nick Lund<br />Attention and Pattern Recognition<br />
  2. 2. Introduction<br /> 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).<br />
  3. 3. Features of pattern recognition<br /> Five principles(Solso,1998):<br /> 1.Quickly and accurately.<br /> 2.Recognise and classify unfamiliar objects.<br /> 3.Accurately recognise shapes and objects from different angles.<br />
  4. 4. Features of pattern recognition<br />4.Identify patterns and objects even when partly hidden.<br />5.Recognise patterns quickly,with ease,and with automaticity. <br />
  5. 5. Features of pattern recognition<br /> Template matching theories<br /> Feature analysis<br /> Prototype theories<br />
  6. 6. Top-down and bottom-up processing<br /> An examination of the theories of pattern recognition raises the question of whether pattern recognition involves top-down or bottom-up processing.<br />
  7. 7. Bottom- up process<br />Template matching theory<br /> Geons (Structural- description theory)<br /> Feature theory<br /> Prototype theory<br />
  8. 8. Template matching theory<br />External stumuli matches internal template<br /> Vast numbers of templates are stored<br /> Templates are created by experience<br />E.x.: visit Russia<br />
  9. 9. A<br />A<br />A<br />A<br />Problems:<br />1) Only occurs when there’s a one-to-one match<br /> Payne and Wenger (1998)<br />
  10. 10. 2) Where are all these templates stored?<br />3) Slow process<br />Ex.: recognize 1000-1500 letters a minute<br />4) To recognize new variations of a pattern (Solso, 1998)<br />
  11. 11. Geons (Structural- description theory)<br /> Biederman (1987)<br /> Limited number (24) of simple geometric shapes , or geons for us to analyse patterns.<br />Ex.: mug v.s. bucket<br />
  12. 12. Geons<br />
  13. 13. Advantage:<br />Recognize pattern from different angles<br /> Disadvantage:<br />Can’t explain why we recognize a particular chair.<br />Ex.: My face v.s. my friend’s face<br />
  14. 14. Feature theory<br /> Patterns are recognized by analysis of the individual features of the pattern.<br />Ex.: MANGO<br />M<br />A<br />
  15. 15. Four stages of pattern recognition<br />Image demons: record the image and pass it<br />Feature demons: analyse the image for specific feature<br />Ex.: <br />Pandemonium model (Selfridge, 1959)<br />
  16. 16.
  17. 17. Cognitive demons: detect the present feature and shout<br />Decision demons: pick up the loudest feature<br />
  18. 18. Advantage:<br /> More flexible than template theory<br />Ex.: A , regardless of size, shape or orientation<br />Neisser:<br /> M -> N H M V -> longer RT <br /> (more distracter)<br /> M -> O M Q G -> shorter RT<br />
  19. 19. Disadvantage:<br />Fail to account for the effects of context and expectations<br />Ex.:<br />Two experiments which can’t explain feature theory<br />Fail to detect “t” in “the” (Healy)<br />Teacup, eyebrow -> cup, eye ; eac, ebr (Inhoff and Topolski)<br />
  20. 20. Eysenck and Keane:<br /><ul><li>How can we recognize patterns when their features are hidden from view?</li></ul>Relationship between the features<br /><ul><li>Ex. : T v.s. L</li></li></ul><li>The biology of feature theory<br /> Hubel and Wiesel (1959)<br /> In visual cortex:<br />Simple cells: particular orientation, specific location<br />complex cells: lines or edges, in all visual field<br />Hypercomplex cells: length and angles, combination of features <br />
  21. 21. Disadvantage:<br />Some questioned the existence of hypercomlex cells<br />How specialized they need to be?<br />Run out of cells<br />
  22. 22. Prototype theory<br /> External stimuli matches with internal abstract prototype<br />Ex.: R, compare to all other “R”s <br /> Solso(1998): two theoretical models<br />Central-tendency model:<br /><ul><li>The average, mean</li></ul>Attribute-frequency model:<br /><ul><li>Most common combination, mode</li></li></ul><li>Advantage:<br />More “economical” than template theory<br />Don’t need templates for every shape, size, orientation<br />Explain the speed of recognition of letters, words and patterns / novel stimuli<br />
  23. 23. Disadvantage:<br />can’t explain the effect of context (Eysenck, 1993)<br /> old woman v.s. young lady<br />B, R, P have similar prototype<br />
  24. 24. Top-down processing<br /> Word superiority effect <br /> Rat-Man demonstration<br />
  25. 25. Rat-Man demonstration<br />
  26. 26. Rat-Man demonstration<br />
  27. 27. Rat-Man demonstration<br />
  28. 28. The effect of context<br />
  29. 29. Summary<br />Pattern Recognition <br />Theories<br />Template matching<br />Feature analysis<br />Prototype <br />Central-tendency<br />Attribute- frequency<br />
  30. 30. Summary<br />Word superiority effect<br />Rat-Man demonstration<br />Pandemonium model<br />Geons<br />Top-down processing<br />Bottom- up processing<br />
  31. 31. THE END<br />