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Perception and Pattern Recognition

Perception and Pattern Recognition. What types of information do we use to perceive the world correctly? What are the major theories about how we recognize patterns? What are the strengths and weaknesses of these theories?. Types of Perceptual Processes.

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Perception and Pattern Recognition

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  1. Perception and Pattern Recognition • What types of information do we use to perceive the world correctly? • What are the major theories about how we recognize patterns? • What are the strengths and weaknesses of these theories?

  2. Types of Perceptual Processes • Bottom-up - work up from sensory info. • Top-down - apply knowledge and experience

  3. Top-Down Effects • Chess masters remember chess board patterns better than novices (Chase & Simon,1973) • Easier to recognize objects in context (Palmer,1975) C

  4. Illusory Contours

  5. Template Matching Theory • Recognize patterns by matching stimulus to template • Works in price scanners

  6. Problems with Template Matching R R • Differences in orientation R R • Differences in size R R R R • Differences in form

  7. Feature Analysis • Identify simple features of patterns • Combine features into complex patterns • Hubel & Wiesel (1965) found feature detector neurons in cats • Visual search: easier to find target when it doesn’t share features with the background (Neisser,1964)

  8. Find the Z

  9. Treisman’s Feature Analysis Theory • Preattentive Stage: detect visual features • Pop-Out • Illusory Conjunctions • Focused Attention Stage: combine features into objects

  10. Problems with Feature Analysis • Two different patterns can have the same features • Patterns may not have any features that are required H

  11. Gestalt Approach • Law of Pragnanz • Similarity • Good Continuation • Proximity • Common Fate • Familiarity

  12. Good continuation

  13. Prototype Matching Theory • Prototype - “best” or “typical” representation of a pattern • Stimulus is compared to prototypes • Uncertainty in pattern recognition • Pseudomemory (Solso & McCarthy,1981)

  14. Study These Faces...

  15. Which Did You See? A C B • A is the prototype; it was not seen. • B was not seen. • C was one of the original faces.

  16. Evolutionary Psychology • What problems must the brain solve to perceive accurately? • Figure-ground separation • Inverse projection problem • Occlusion • Edge perception

  17. Evolutionary Psychology • How does the brain solve these problems? • Top-down and bottom-up • Heuristics • Built-in brain organization • Plasticity

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