IMAGERY

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IMAGERY

• AIMS OBJECTIVES
• The aim of the lecture is to review theories of
  imagery.
• At the end of the lecture you will have learned
  about
• Analogical knowledge
• Paivios theory of knowledge
• Mental rotation and scanning
• Data from neuropsychology on imagery and visual
  perception

• CORE READING
• Parkin, A. (2000). Essential Cognitive
  Psychology. Psychology Press, Chapter 9.
• SUPPLEMENTARY READING
• Behrmann, M. Winocur, G., Moscovitch, M (1992).
  Dissociation between mental imagery and object
  recognition in a brain damaged patient. Nature,
  359(6396), 636-637.
• Behrmann, M. (2000). The mind's eye mapped onto
  the brain's matter. Current Direction in
  Psychological Science, 9(2), 50-54.

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Lecture questions
Occipital lobe

• How do we use analogy in cognitive processing?
• Does imagery depend on the same cognitive/
  neurological processes as visual perception?
• What colour are the dots on Mr Blobbys outfit?
  Millionaire 03

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Abstract Pylyshyn
Literal and each part of representation
is depicted once only
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Paivios dual coding theory

• Two independent but linked symbolic (rule)
  systems for organising knowledge in LTM.

• Imagery system
• processes nonverbal, perceptual representations.
• Verbal system
• processes linguistic information (words).

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fish
ImagesRight hemisphere
Words Left hemisphere
fish wish
drawing writing
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Eidetic memory

• Photographic memories
• chess players
• children (1/20).
• Ancient Greeks believed all thought was based on
  analogy and developed the method of loci.
• Hat, farmer,tree,bell, etc..

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Mental rotation

• Shepard and Metzler (1971) Science.
• Asked participants to match 3D shapes that were
  rotated in a 360 degree plane.

• Participants take longer to decide that the
  shapes are the same or different with a larger
  extent of angular disparity.
• Participants mental rotation ability is
  veridical to rotation of the objects themselves.

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Same pair
Same pair
Different pair
Directly proportional
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Scanning experiments
rocks
tree
tent
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rocks
tree
tent
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Kosslyns computational model

• Kosslyn (1983, 1994) proposed a computational
  model of imagery.
• The model has two permanent stores of information.

• Image files
• Information about the shape of an object.
• Propositional files
• Information about the meaning of an object i.e.
  verbal statements.

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LTM
Store of facts e.g. Brighton is 50 miles from
London
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Image and Mind

• Images are represented in a spatial medium and
  this has a limited capacity (Baddeley).
• Spatial relationships
• relative distance between London and Brighton
  versus Edinburgh.
• Transformation
• allows for mental rotation

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Evidence

• Kosslyn (1975) asked participants to imagine
  either
• (1) an elephant and a rabbit
• (2) a fly and a rabbit.
• Participants took longer to answer questions
  about when they could scan to the details of a
  rabbit in condition (1) than in condition (2).

• Logic Propositions are the same in both of these
  conditions although the spatial relations change.
• This finding is an example of an emergent
  property of the spatial properties of the image
  and not about propositions.

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Brain imaging methods

• Experimenter can watch the brain working on a
  cognitive task.
• Increased blood-flow in one part of the brain is
  assumed to be correlated with cognitive activity.
• The brain scanner detects changes to blood-flow
  when the conditions in the cognitive task change.

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Neuropsychological evidence

• Goldenberg et al (1992) used Positron Emission
  Tomography (PET) to test whether imagery requires
  visual areas of the brain.
• They measured regional cerebral blood-flow (rCBF)
  while answering questions about objects.

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Neuropsychological evidence
Analogical visual process?

• Half required imagery (e.g., rotate the letter
  p).
• Half no imagery (e.g., is p a vowel or a
  consonant?).
• Imagery questions resulted in a blood-flow
  increase to occipital regions of the brain but
  non-imagery based questions did not
• Behrmann report agnosic patient with imagery
  intact.

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Unilateral neglect of space

• Patients fail to see objects on left hand side of
  space.
• Attentional disorder
• cueing effects
• automatic attention is impaired.
• Imagery disorder too?

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Bisiach and Luzzatti (1978)

• Milanese neglect patients asked to imagine the
  view from Piazza del Duomo.
• Asked to imagine viewing the Piazza when looking
  toward the cathedral.
• Patients ignored all of the landmarks to imagined
  left hand side of space.

ignored
reported
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Bisiach and Luzzatti (1978)

• Next, asked patients to imagine they were
  standing at the cathedral steps and looking in
  the opposite direction.
• Patients report landmarks that were previously
  ignored and now neglect landmarks on the left.
• So, internal images can also show neglect.

ignored
reported
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Summary

• Studies of mental rotation show people use
  imagery.
• Kosslyns model assumes that imagery is
  analogical and can explain data from studies of
  mental rotation.
• Neuropsychological evidence shows that similar
  brain areas are involved in imagery and visual
  perception.