Cognitive Psychology

1. Cognitive Psychology Part III: Some research areas within Cognitive Psychology HKU

2. Categorization Representation Memory Attention HKU

3. Categorization “The process by which distinct entities are treated as equivalent” (Medin & Aguilar, 1999) HKU

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6. Categorization(Categorical Perception) Partitioning a continuous physical spectrum into discrete categories HKU

7. Color Perception HKU

8. Why categories? • The world is very complex. • We cannot keep track of every individual item in the world – we must group similar things together. • We cannot process all information available to us – we must selectively attend to what is important to us (what is important for making these groupings). HKU

9. Some questions about categories • What information and processes do we use to form categories? • How does using categories affect our perception and behavior? HKU

10. Representation How is information represented in the mind? HKU

11. What is a mental representation? • A systematic correspondence between some element of a target domain and some element of a modeling (or representation) domain. HKU

12. For example Target domain (real world) Model domain (representation) HKU

13. The target contains 3 rectangles. • The model contains 3 sets of dots. • The relevant structure in the target is the height of the rectangles. • The relevant structure in the model is the number of dots (height, width is irrelevant). • Systematic correspondence is that the number of dots increases as the height of the rectangle increases. HKU

14. An alternative 20 4 8 Target domain (real world) Model domain (representation) HKU

15. And another A C B Target domain (real world) Model domain (representation) HKU

16. Possible representations • Symbols: Representations are amodal – they bear no necessary resemblance to the concept or percept they represent. The systematic correspondence between the two domains may be a matter of convention (only). • Like variables in algebra, the words dog, Hund, [sabaka] and [gau2], or the numerals 20, 4, and 8, or A, B, and C, for the rectangles in the rectangle example. HKU

17. Possible representations • Images: Representations resemble what they represent in some non-arbitrary way. The systematic correspondence between the two domains is iconic. • e.g. photographs, maps, caricatures, the number of dots for height (number of cm), etc. HKU

18. It seems almost obvious that some things might be represented as images visual percepts: It seems less obvious that other things are represented as images abstract concepts: The feeling of being tired of hearing about brown dogs. Symbols vs. Images • Some things seem to fall somewhere in between. • The concept of dog (not a particular dog, but dogness in general). HKU

19. Evidence for mental images • Pictures of abstract 3D objects. • Object-matching task: “Are these two objects the same or not?” • On correct “same” responses, subject took longer when there was a greater angle of rotation between the two objects. • This suggests they were rotating the images until they matched up in their “mind’s eye”. (From Shepard & Metzler, 1971) HKU

20. Property-listing task: “Name all the properties you can think of that are true of…” Watermelon Green, round, heavy, buy them in the summer, etc. Half of a watermelon Pink, has seeds, wet, sweet, heavy, etc. Responses depend in part on imagery. (From Wu, 1995, cited in Goldstone & Barsalou, 1998) More evidence of mental imagery HKU

21. Mental representations • Cognitive psychologists (mostly) agree that: • Human information processing depends on the mental representation of information. • But they disagree (frequently) on: • What is the nature of mental representations? HKU

22. Memory What processes and representations are involved in the storage and retrieval of information? HKU

23. The magical number 7 ± 2 (Miller, 1956) “Chunking”, schemas, and elaboration How many numbers can you remember? 1 4 9 2 1 7 7 6 1 8 4 1 1 9 9 7 1492 1776 1841 1997 HKU

24. Schemas • Person Schemas: we use personality categories to classify people and these often lead us to infer properties that aren’t present (prejudices, stereotypes). • Also Event and Place Schemas. • Dining in a restaurant • Lecturer’s office HKU

25. Example: What objects are in this office? Brewer & Treyens, 1981 HKU

26. Schemas can affect memories • Subjects spent less than a minute in the room. • Most recalled a chair and a desk. • About 1/3 recalled books. • There were no books in the office. HKU

27. Attention Selecting the right information from the world. HKU

28. Automatic Involuntary Fast Effortless Controlled Voluntary Slower Takes effort Automatic vs. Controlled processing • Automatized • More automatic • Faster • Takes less effort HKU

29. Stroop Effect HKU

30. Cat Mail Fish Watch Desk Stroop Effect Wish Bird Mouse Phone Ear Shoe Hat Hand Bag Pin Screen Face Card Wire Dog HKU

31. Red Yellow Blue Green Blue Stroop Effect Blue Blue Yellow Blue Yellow Green Red Green Yellow Red Yellow Green Red Red Green After Stroop (1935) and Coren & Ward (1989) HKU

32. Next Week Perception • Top-down vs. Bottom-up Processing • Perception and categorization • Please look at • Papathomas, T. V. (1999). The brain as a hypothesis-constructing-and-testing agent. In Lepore, E. & Pylyshyn, Z. (Eds.) What is Cognitive Science (pp.230-247). Oxford, Blackwell. HKU

33. Bibliography • Barsalou, L. W. Cognitive Psychology: An Overview for Cognitive Scientists. Hillsdale, NJ, Lawrence Erlbaum and Associates. • Coren, S. & Ward, L. M. (1989). Sensation and Perception, Third Edition. Fort Worth, NJ, Harcourt Brace Jovanovich. • Goldstone, R. L., & Barsalou, L. W. (1998). Reuniting perception and conception. Cognition, 65, 231-262. • Lee, Y.-S., Vakoch, D. A., & Wurm, L. H. (1996). Tone perception in Cantonese and Mandarin: A cross-linguistic comparison. Journal of Psycholinguistic Research, 25, 527-542. • Medin, D. L. & Aguilar, C. (1999). Categorization. In Wilson, R. A. & Keil, F. C. (Eds.) The MIT Encyclopedia of the Cognitive Sciences (pp. 104-106). Robert A. Wilson and Frank C. Keil. Cambridge, MA, MIT Press. • Miller, G. A. (1956). The magical number seven plus or minus two: Some limits on our capacity for processing information. Psychological Review, 63, 81-97. • Shepard, R. N., & Metzler, J. Mental rotation of three-dimensional objects. Science, 171, 701-703. • Stroop, J. (1935). Studies of interference in serial verbal reactions. Journal of Experimental Psychology, 18, 624-643. • Wu, L., (1995). Perceptual Representation in Conceptual Combination. Doctoral dissertation, University of Chicago HKU