Mental Imagery - University of Idahowebpages.uidaho.edu/psyc325/secure/20/20.slides.pdf · · 2014-09-04Cognitive Psychology University of Idaho © Steffen Werner - 2004 Working

CognitivePsychologyCognitivePsychology

University of Idaho © Steffen Werner - 2004Working Memory.20. 1

Mental Imagery

Lesson IV: Working Memorymodule 20




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



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?



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



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



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)



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



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)



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



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



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



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



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

Documents

Mental Imagery - University of Idahowebpages.uidaho.edu/psyc325/secure/20/20.slides.pdf · · 2014-09-04Cognitive Psychology University of Idaho © Steffen Werner - 2004 Working