cog5 lecppt chapter10
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© 2010 by W. W. Norton & Co., Inc.
Visual Knowledge
Chapter 10Lecture Outline
Chapter 10: Visual Knowledge
Lecture OutlineVisual ImageryLong-Term Visual MemoryThe Diversity of Knowledge
Visual Imagery
A variety of day-to-day problems seem to require the use of visual imageryHow many windows are in your apartment?Was David in class yesterday?Will this sweater look good with your blue
pants? What is the nature of these mental
images?
Visual Imagery
Francis Galton (1883) Introspection to study mental imagery
Self-reports suggested they could inspect mental images as pictures
The participants also differed widely in the amount of detail their mental images seemed to contain. (Or were these differences in self-reporting style?)
Studies of visual imagery in the last 50 years have avoided introspection and instead asked participants to do something with their images—to read information off them or manipulate them in some way.
© 2010 by W. W. Norton & Co., Inc.
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Visual Imagery
Chronometric studiesAsk participants to manipulate the mental
imagesObserve how long these manipulations take
Visual Imagery
Kosslyn (1976) asked participants to answer yes/no questions about their mental images. Imagined cat, confirm that cats have heads faster
compared to confirming that cats have claws (mental imagery)
The reverse was true if the participants were asked to think about cats, not to imagine them (propositional knowledge)
This suggests that as the mode of representation changes, so does the pattern of information availability
Visual Imagery
Image-scanning procedure, Kosslyn et al. (1978)
Memorize this map Scan from one landmark
to another on the imagined map
Visual Imagery
Imagined distance correspondsto real distance
Thus, mental images seem to preserve the spatial layout and geometry of the represented scene.
Visual Imagery
Does a mouse have whiskers?
Visual ImageryMental-rotation task Which of these pairs is the same?
The further the distance, the longer it takes
Visual Imagery
The greater the angle,the longer the time
As if they were rotating the images in real life
Visual Imagery
Demand characterDid image-scanning and mental-rotation
experimenters somehow cue people?Even without instruction, participants still form
images
Visual Imagery
Less accurate whensignal and image are the same
More likely to wrongly choose that the stimulus matches the image when signal and image are both visual or auditory
Mental imagery seems to use perceptual mechanisms.
Visual imagery interferes with detecting dim visual stimuli, and auditory imagery interferes with detecting quiet tones.
Visual Imagery
However, if we are imagining a stimulus related to the one we are about to perceive, facilitation occurs.
ImageryCan interfere with perception (mismatching)Can facilitate perception (matching)
Visual Imagery
Occipital areas used for early visual processing Active during visual imageryPatients with unilateral neglect may also
neglect the left side of space in their mental images
Transcranial magnetic stimulation (TMS) disrupts mental imagery
Visual Imagery
Patient can only see the right side of the plaza
Patients with unilateral neglect may also neglect the left side of space in their mental images.
Visual Imagery
Patient can only see the right side of the plaza
Visual Imagery
Functional equivalence between imagery and perception.
Visual acuity higher—can see two dots
Visual acuity lower—need more space to see two dots
For both perception and imagery, acuity is greatly reduced if the dots are not in the center of vision.
Visual Imagery
People who have been blind since birth also demonstrate the same effects in mental-rotation or image-scanning tasks, with response time being proportional to the distance traveled
Thus, we need to distinguish between visual imagery and spatial imagery
Spatial imagery may be based in movement or body imagery, or it may be abstract and not tied to any one sense
Visual Imagery
Vivid imagers versus non-imagersReport seeing images betterSelf-reported “vivid imagers” perform no
differently than “non-imagers” on tasks that depend on spatial imagery.
Vivid imagers better for visual imagery
Visual Imagery
Eidetic or photographic memory Extremely rare Found in some autistic
individuals eidetic imagery
Visual Imagery
Mental images different from pictures Perception is not neutral and goes beyond the
information given Interpretations are present in images
Visual Imagery
Imagery only preserves one interpretation
Visual Imagery
Thus, images (like percepts) are organized depictions
One way to think about mental images is as a package that includes the depiction itself as well as a perceptual reference frame
For instance, the duck/rabbit image, understood as a duck, is associated with the reference frame “facing to the left”
Visual Imagery
Don’t know what this is? Close your eyes and
rotate it 90º clockwise
Visual Imagery
Sometimes putting an idea down on paper can help make a discovery that requires a change in the reference frame
Visual Imagery
Mental images Alternative to verbal descriptionSpatial layout and geometry are preservedReflect perceptual interpretation and are
associated with reference frames
Long-Term Visual Memory
What is the nature of visual imagery taken from long-term memory?
Long-Term Visual Memory
Images in long-term memory Stored in a piecemeal fashionMust activate representation of image frameElaborate on this frame Images that have more parts or detail take
longer to create
Long-Term Visual Memory
Generating three rows faster
Generating four columns slower
Long-Term Visual Memory
Long-term visual memory Image files
Recipes or instructions for how to construct an active mental image of the object or shape
May represent visual information in terms of propositions, or verbal labels
Long-Term Visual Memory
Will have more accuratememory for something that is either blue or green
Will have less accurate memory
Long-Term Visual Memory
Interpretation changes the reconstruction of the image
Long-Term Visual Memory
Which is farther south, New Orleans or Tijuana?
Which is farther north, Seattle or Montreal?
Long-Term Visual Memory
Imagery helps memory, especially with an interaction
Long-Term Visual Memory
Dual codingHigh-imagery words, for instance, can be
coded as both word and imageLow-imagery words only have a verbal code
Long-Term Visual Memory
Studies of memory for pictures illustrate ways in which long-term visual memory reflects general principles of memory, such asPrimacy and recencyEncoding specificitySchemata or generic knowledgeSpreading activation and primingFamiliarity and source memory
Long-Term Visual Memory
Schematic retrieval (Friedman, 1979) found that participants
failed to notice differences between previously seen and new pictures if both were consistent with a schema (e.g., a kitchen or barnyard)
Pictures that contained violations of a schema (e.g., kitchen with a fireplace) were readily noticed
Long-Term Visual Memory
Boundary extension Information is filled in
that was not present in the picture
The Diversity of Knowledge
Visual working memory is based in imagery and uses perceptual, spatial representations Image scanning, rotation, zooming
Visual long-term memory is based on propositional knowledge and shares many representational principles with other forms of long-term memory Spreading activation, priming, schematic knowledge
Chapter 10 Questions
1. Based on image-zooming experiments, which of the following would participants be slowest to identify in a mental image?
a) the whiskers of a cat standing alone
b) the ears of a rhinoceros positioned next to a squirrel
c) the whiskers of a cat positioned next to an ant
d) the wings of a butterfly positioned next to a hippopotamus
2. Participants answering questions about geography might erroneously claim that San Diego, California, is farther west than Reno, Nevada, when in fact Reno is farther west. This example suggests that spatial information is sometimes
a) stored in long-term memory as propositions.b) stored in short-term memory as propositions.c) stored in long-term memory using a
perceptual code.d) stored in short-term memory using a
perceptual code.
3. Which of the following is evidence that the brain areas involved in perception and mental imagery are similar?
a) using TMS to disrupt Area V1 results in parallel problems in vision and visual imagery
b) a patient suffering from neglect syndrome may neglect the left half of imagined scenes
c) stroke patients who lose the ability to see color also lose the ability to imagine color
d) all of the above
4. What is the worst description of individual differences in imagery ability?
a) Most people are able to form images.
b) Some people are good at visual imagery, and others are good at spatial imagery.
c) Within visual imagery and spatial imagery, most people have some strengths and some weaknesses.
d) Imagery ability is fairly uniform from one person to another.
5. Which of the following is evidence that some forms of imagery are spatial and not visual?
a) Blind people can complete mental-rotation experiments as quickly and accurately as sighted people.
b) There is no interference when people are asked to judge the brightness of a light while making a mental-rotation decision.
c) Patients such as L.H. may perform well on spatial imagery tasks but fail on visual imagery tasks.
d) all of the above
6. Participants are asked to form mental images of ambiguous pictures that were viewed earlier. When asked to ___ the image and then reinterpret it, they succeed.
a) imagine
b) hear the sound of
c) imagine interacting with
d) draw
7. Which of the following mental-image reinterpretations would be the HARDEST?
a) The sought-after discovery is compatible with the image’s depiction but not its reference frame.
b) The sought-after discovery is compatible with the image’s reference frame but not its depiction.
c) The sought-after discovery is compatible with both the image’s depiction and its reference frame.
d) The sought-after discovery is compatible with neither the image’s depiction nor its reference frame.