2. 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?

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

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

5. Illusory Contours

6. Template Matching Theory  Recognize patterns by matching stimulus to template  Works in price scanners

7. Problems with Template Matching Differences in orientation R R Differences in size R R Differences in form R R R R

8. 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)

9. Find the Z

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

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

15. Gestalt Approach  Law of Pragnanz  Similarity  Good Continuation  Proximity  Common Fate  Familiarity

17. Good continuation

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

19. Study These Faces...

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

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

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