Cognitive Psychology

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Cognitive Psychology

• Part III
• Some research areas within Cognitive Psychology

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• Categorization
• Representation
• Memory
• Attention

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Categorization

• The process by which distinct entities are
  treated as equivalent (Medin Aguilar, 1999)

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Categorization(Categorical Perception)

• Partitioning a continuous physical spectrum into
  discrete categories

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Color Perception
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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).

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Some questions about categories

• What information and processes do we use to form
  categories?
• How does using categories affect our perception
  and behavior?

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Representation

• How is information represented in the mind?

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What is a mental representation?

• A systematic correspondence between some element
  of a target domain and some element of a modeling
  (or representation) domain.

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For example
Target domain (real world)
Model domain (representation)
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• 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.

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An alternative
20 4 8
Target domain (real world)
Model domain (representation)
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And another
A C B
Target domain (real world)
Model domain (representation)
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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.

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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.

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Symbols vs. Images

• 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.

• Some things seem to fall somewhere in between.
• The concept of dog (not a particular dog, but
  dogness in general).

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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 minds eye.
• (From Shepard Metzler, 1971)

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More evidence of mental imagery

• 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)

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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?

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Memory

• What processes and representations are involved
  in the storage and retrieval of information?

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How many numbers can you remember?
1 4 9 2 1 7 7 6 1 8 4 1 1 9 9 7

• The magical number 7 2 (Miller, 1956)

1492 1776 1841 1997

• Chunking, schemas, and elaboration

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Schemas

• Person Schemas we use personality categories to
  classify people and these often lead us to infer
  properties that arent present (prejudices,
  stereotypes).
• Also Event and Place Schemas.
• Dining in a restaurant
• Lecturers office

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Example

• What
• objects are
• in this
• office?
• Brewer
• Treyens, 1981

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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.

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Attention

• Selecting the right information from the world.

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Automatic vs. Controlled processing

• Automatic
• Involuntary
• Fast
• Effortless

• Controlled
• Voluntary
• Slower
• Takes effort

• Automatized
• More automatic
• Faster
• Takes less effort

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Stroop Effect
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Stroop Effect

• Cat
• Mail
• Fish
• Watch
• Desk

Wish Bird Mouse Phone Ear
Shoe Hat Hand Bag Pin
Screen Face Card Wire Dog
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Stroop Effect

• Red
• Yellow
• Blue
• Green
• Blue

Blue Blue Yellow Blue Yellow
Green Red Green Yellow Red
Yellow Green Red Red Green
After Stroop (1935) and Coren Ward (1989)
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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.

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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