Chapter 7 Representation and Manipulation of Knowledge in Memory

Modified: 2006-03-24

I. MENTAL REPRESENTATIONS OF KNOWLEDGE

A. Declarative knowledge--stateable facts (know that)

B. Procedural Knowledge--implementable processes (know how)

C. External Representations: Pictures versus Words

• Representations of a Polar Bear
  • POLAR BEAR (symbolic code)
  • http://images.google.com/images?q=polar+bear&ie=ISO-8859-1&hl=en&btnG=Search+Images (picture, analog code)
  • http://dictionary.reference.com/search?q=polar%20bear (dictionary definition)
• Cognitive Psychologists Study Mental Representations
  • Methods
    • Self report
    • Rationalist approach
    • Empirical support
    • Experiments
    • Neuropsychological studies

D. Mental Imagery

• 1. Imagery (old problem in psychology)
  • Internal representation of environment that is spatial or visual in nature
  • Kosslyn proposes images are used to help solve certain types of problems
    • How many chairs are there in your house?
    • Do bunnies have whiskers?

E. Dual-Code Theory: Analogical Images Versus Symbols--Paivio (1971)

• We use two codes to represent information
  • Image codes- analogue codes, shares some perceptual features
  • Verbal codes- arbitrary symbols to represent items
  • Two codes are linked
• Evidence for Dual Code Theory
  • Paivio compared concrete words (potato, horse) with abstract words (justice, love)
  • Found participant were better able to recall concrete words
  • Concluded that dual code was created for concrete words (analog & verbal label) but not for abstract words
• Additional Evidence for Dual Code
  • Visual information has different characteristics than verbal code
  • Visual information interferes with spatial information
  • Verbal labels interfere with spoken words
  • Shows each type of code is affected by different manipulations

F. Propositional Theory

• Do not store in form of images
• Instead have a "generic" code that is called "propositional"
• Stores the meaning of the concept
• Create a verbal or visual code by transforming the propositional code
  • You know who I'm talking about, the tall, redheaded guy, the one with the burn scar on his left arm. Do you know who I mean?
  • Why do convenience stores have 4, 5, 6 on their doors?

Carmichael, Hogan, & Walters (1932)

• Participants were shown simple figures with one of two verbal labels
  • Carmichael, Hogan, & Walters (1932) Results
    • Later participants were asked to draw items seen
    • Participants distorted the images to fit the labels
    • Interpreted as the images may be stored as propositional
    • information

• 4. Propositional Limits (in ambiguous figures)
  • a) Two manipulations for mental reinterpretation of ambiguous figures
    • i) Mental Realignment--duck's bill or rabbit's ears (duck's back is rabbit's front)
    • ii Mental Reconstrual--duck's bill equals rabbit's ears
  • b) Hints for reinterpreting ambiguous figures
    • i) Implicit reference-frame hint--show similar images, no instructions
    • ii) Explicit reference-frame hint--give direct verbal hints
    • iii) Attentional hint--look at a part of the image, what does it look like?
    • iv) Construals from "good" parts--look at the "good" parts of image

II. MENTAL MANIPULATIONS OF IMAGES

Functional-equivalence hypothesis

A. Mental Rotations--Shepard & Metzler (1971)

• Subjects had to decide whether displays had two similar shapes
• Some pairs were similar, but rotated to various degrees
• Results
  • Mental Imagery Studies Demonstrate
  • Active process
  • Response times are proportional to degree of rotation (180 degrees is maximum. Why?)
  • People can rotate images in three-dimensional space as easily as two-dimensional space
  • Images are "Mental Sculptures"

B. Image Scaling--Kosslyn (1975)

• Examine how participants scan and use images
  • Some participants imagine an elephant next to a rabbit
  • Others imagine a rabbit next to a fly
  • Then answer questions about the rabbit
    • Does the rabbit have whiskers?
    • Does the rabbit have ears?
    • Does the rabbit have a beak?
  • Reaction time to answer is measured
  • Judgments faster for rabbits next to smaller creatures (larger visual image)

 C. Image Scanning--Kosslyn (1983)

• Memorize map
• Later ask to scan image
• Manipulate distance between items in scan
  • Hut to grasses
  • Lake to Hut
• Measure reaction time
• Results
  • Linear relationship between the distance to scan and actual reaction time of participants
  • Further support for functional-equivalence hypothesis
• Mental images are internal representations that operate in a way that is analogous to the functioning of the perception of physical objects

III. SYNTHESIZING IMAGES AND PROPOSITIONS

D. Johnson-Lairds' Mental Models--(1983)

• Proposed there are three types of mental representations
  • Propositional representations which are pieces of information resembling natural language
  • Mental models which are structural analogies of the world
  • Mental imagery which are perceptual models from a particular point of view
• Characteristics of a Mental Model
  • A representation of a described situation rather than a representation of a text itself or the propositions conveyed by a text
  • The structure corresponds to the functional relations among entities as they would exist in the world
  • A simulation of events in the world, either real or imaginary
• Kerr (1983) studied participants who were blind
  • Created a tactile Kosslyn Map study equivalent
  • Participants had to study the island given a physical map to touch
  • Asked the same scanning questions
  • Found the same pattern of results&emdash;longer distances, longer reaction times
• Other modalities
  • Think about non-visual imagery
    • sound images
    • smell images
    • touch images
• Spatial images
  • Think about waking up in a strange bed. Which way are you pointed?

IV. SPATIAL COGNITION AND COGNITIVE MAPS

Cognitive Maps--Tolman and Honzik (1930)

• Tolman &endash; Rats
• von Frisch &endash; Bees
• Thorndyke &endash; Humans
• Creating Cognitive Maps
  • Gain increased spatial knowledge
  • Using three types of knowledge
    • Landmark (special buildings)
    • Route-road (procedures to get to one place from another)
    • Survey (global map-like view)
• Heuristics Affecting Cognitive Maps
  • Density Heuristic
    • More landmarks between two points, the greater the distance we estimate
  • Right angle bias
    • Streets are drawn at 90-degree angles (even when they are not)
  • Symmetry heuristic
    • Irregular geographic boundaries are made regular (e.g., Americans straighten out the Canadian border)
  • Rotation heuristic
    • Tend to 'regularize' tilted landmarks in maps to appropriate E-W or N-S axis
  • Alignment heuristic
    • Students view two maps of the Americas
    • One a correct map, and a second map which was altered (South America was moved westward with respect to North America)
    • A majority of students thought the altered map was the correct one
• Exercise:
  • Draw a floor plan (1st floor) of Academic Building Click here
  • Draw a floor plan (1st floor) of Aiken Building Click here