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CognitivePsychologyCognitivePsychology
University of Idaho © Steffen Werner - 2004Working Memory.20. 1
Mental Imagery
Lesson IV: Working Memorymodule 20
CognitivePsychologyCognitivePsychology
CognitivePsychologyCognitivePsychology
University of Idaho © Steffen Werner - 2004Working Memory.20. 2
The basic phenomenon of mental imagery
The phenomenon– Most people report of being able to visualize situations
before their “mental eye”– Most people are able to generate arbitrary compositions
of scenes they never experienced in their mind(think of a pink elephant on top of the space shuttle)
The scientific questions surrounding imagery– Does the phenomenological experience correspond to a
particular way of processing perceptual information?– What kind of information is being processed in visual
working memory?• the abstract meaning of visual objects vs.• the mind “re-perceiving” perceptual memories
CognitivePsychologyCognitivePsychology
University of Idaho © Steffen Werner - 2004Working Memory.20. 3
Specific questions
What can we do with our mental images?– Can we visualize something and then re-perceive it to
gain new insights / new information?– Can we mentally simulate events and “see” what is going
to happen?
How similar is imagery to perception?– Does imagery follow the same rules as perception?
(functional equivalence of imagery and perception)
Is imagery just an epi-phenomenon?– Could imagery be irrelevant and merely rely on the
output of other non-imaginal processes?
What is the cortical basis for imagery?– Do imagery and perception share the same processing
areas in the brain?
CognitivePsychologyCognitivePsychology
University of Idaho © Steffen Werner - 2004Working Memory.20. 4
Types of mental representations
Formats of mental representations– Content of a representation (information)– Format of a representation (medium, form)
Propositional representations– An abstract, amodal representation of information– Smallest meaningful unit that is either true or false– Examples: wet(shower) or larger(elephant, mouse)
Imagistic / analog representation– A modality specific representation of information– The structure / format of the representation carries
important information and is structurally similar tothe represented event / situation
– Examples: a map of an area or a photograph
CognitivePsychologyCognitivePsychology
University of Idaho © Steffen Werner - 2004Working Memory.20. 5
A map: a mixed representation
Maps contain analog and symbolic information– The general 2D structure of the map (approximately
analogous to spatial relations on earth’s surface)– Items within the map
are symbolic– Designed to convey
information– Don’t accurately
represent the physicalobjects
You are here
CognitivePsychologyCognitivePsychology
University of Idaho © Steffen Werner - 2004Working Memory.20. 6
Working memory and mental imagery
Visual mental imagery:The domain of the visuo-spatial sketch pad– Most tasks investigated in the imagery literature rely
on temporary representations in working memory– Visualization is the main purpose of the sketch pad
The role of imagery in the Brook’s task– Visualization of the F– Walking around the F and changing perspectives
Additional modalities of mental imagery– Auditory imagery (imagine the sound of a bell)– Haptic (imagine touching the tip of a fork)– Motor imagery (imagine skiing down a hill for a race)
CognitivePsychologyCognitivePsychology
University of Idaho © Steffen Werner - 2004Working Memory.20. 7
Kosslyn’s studies of mental imagery
How visual are visual mental images:The idea of functional equivalence– In perception, it is more difficult to perceive detailed
information if the resolution is low– In the physical world, it takes longer to scan a large
distance than a shorter distance– Some patients have specific perceptual deficits (e.g.,
missing some part of the visual field)
Kosslyn’s general approach– Comparing performance during mental imagery tasks
with the predicted performance from physically orperceptually analogous tasks
CognitivePsychologyCognitivePsychology
University of Idaho © Steffen Werner - 2004Working Memory.20. 8
Kosslyn’s famous island scanning study
Imagine a dot flying from the house to the tree…
– Tell me when you arrive
– Image scanning - linear relation between imagedistance and reaction time (r > .95)
CognitivePsychologyCognitivePsychology
University of Idaho © Steffen Werner - 2004Working Memory.20. 9
Mental scanning, scaling, and other effects
Answering “visual” questionsabout simple objects
– Imagine the object next to a …• Fly (small context, object will
be imagined large)
• Elephant (large context, objectwill be imagined small)
– Reaction times lower whenimagined object is small
CognitivePsychologyCognitivePsychology
University of Idaho © Steffen Werner - 2004Working Memory.20. 10
Kosslyn’s mental imagery model
The visual buffer– Central component of Kosslyn’s model– In addition to proposing a visuo-spatial working
memory component, the visual buffer representsinformation in a particular, analog 2D structure
Generation of images– Images can be generated from descriptions in long-
term memory or through direct perceptual input– The representations in the buffer are similar
Image manipulation and scanning– The buffer has built in image transformation
processes like scanning, scaling, rotating, or panning– Information can be read out of the buffer through
visual processing
CognitivePsychologyCognitivePsychology
University of Idaho © Steffen Werner - 2004Working Memory.20. 11
Chambers and Reisberg (1985):Imagining ambiguous images
How much information can we glean from a visual,mental image?
– When shown an ambiguous image (e.g., the duck-rabbit picture), participants usually only see oneinterpretation during the initial glance
– Participants were to visualize their image and comeup with the second interpretation
– None of their participantswas able to find the secondinterpretation, even if theywere able to draw it later andsee it in their drawing
– With substantial hints, peoplecan sometimes find it
CognitivePsychologyCognitivePsychology
University of Idaho © Steffen Werner - 2004Working Memory.20. 12
Critiques of “analog” imagery theories
First problem: the indeterminable format– Computations rely on specific data formats and also
the processes are operating upon that data– It is theoretically impossible to determine the format
of a representation solely based on behavior– Many different representations can be
“informationally” equivalent– However, some representations are better suited for
some operations than others (e.g., roman numerals)
Divide C by X vs. 100 by 10Change engraving from XI to XII vs. 11 to 12
CognitivePsychologyCognitivePsychology
University of Idaho © Steffen Werner - 2004Working Memory.20. 13
Critiques of “analog” imagery theories
Second problem: demand characteristics– Participants might be able to correctly guess what
kind of relationship the researcher wants to find– Confounding of perceptual and conceptual levels
Third problem: severe limitations of functionality– People often over-estimate what people can do with
their mental images (e.g., reading off information)– There are severe limits to the amount of information,
detail, and creative interpretations based on imagery
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