Chapter 10 Visual Imagery
Neuropsychological Case Studies
-Unilateral neglect
Visualizing interacting images to improve Memory
bizarreness is not necessary
Mental Imagery
experiencing a sensory impression in the absence of sensory input
Connection between imagery and perception
if imagery affects perception, or perception affects imagery then imagery and perception have access to the same mechanisms
imagery debate
imagery is based on spatial mechanisms (like those involved in perception) vs. imagery is based on mechanisms related to language called propositional mechanisms
pegword technique
involves imagery in which you associate visualizing an item with a concrete word
As described in your text, the pegword technique relies on all of the following EXCEPT: a. propositions. b. rhymes. c. associations. d. visualizations.
propositions.
propositional representation
representation in which relaionships can be represented by abstract symbols (ex. equation) or a statement
classic demonstration of interaction between perception and imagery
-Perky: asked subjects to project visual images of common objects onto a screen and then describe these images - Perky was back projecting a very dim image of the object on the screen - results: the subject's description of their images matched the images Perky was projecting - none of the subjects noticed there was an actual picture on the screen meaning that they had mistaken an actual picture for a mental image
imageless thought debate
arose from the idea of a link between imagery and thinking - thought is impossible without image vs. thinking can occur without images
demonstrating interactions between perception and imagery
- Farah: instructed subjects to imagine either the letter H or the letter T on a screen - once subjects had formed a clear image on the screen they pressed a button that caused 2 squares to flash (one after the other) - one of the squares contained a target letter (either an H or a T) - the subjects task was to indicate whether the letter was in the first square of the second one - result: the target letter was detected more accurately when the subject had been imagining the same letter rather than the different letter
evidence for thinking not requiring imagery
- Galton: people with difficulty in forming visual images were capable of thinking - behaviorists brand the study of imagery as unproductive because visual images are invisible to everyone except to the person viewing them
tacit knowledge explanation
- Based on experiment (Kossyln) in which it is determined that creating a spatial mental image and locating components of it cooresponds with reaction time - the reaction times can be explained in terms of propositional representations AND because subjects are responding to Kossyln's task based on what they know usually happens when looking at a real scene - the explanation is given its name because it states that subjects unconsciously use knowledge about the world in making their judgements
Case of impaired perception and normal imagery
- Berhamann studied C.K. - C.K suffered from visual agnosia (inability ro recognize objects) ex. labled a feather duster as a dart - C.K could recognize parts of objects but could not integrate them into a meaninful whole - C.K was able to draw objects from memory (a task that depends on imagery)
Objections to tacit knowledge explanation
- Pinker: presented a 4 dot display and then after a 2 second delay, an arrow was presented - the subjects task was to indicate whether the arrow was pointing to any of the dots they had just seen - result: although the subjects were told not to use imagery or to scan outward from the arrow, they took longer to respond for greater distances between the arrrow and the dot - b/c the subjects did not have time to memorize the distances between the dot an arrow before making a judgement, it is unlikely they used tacit knowledge about how long it should take to get from one point to another
pegword technique
- associate items to be remembered with concrete words - pair each of these things with a pegword - create a vivid image of things to be remembered with the object represented by the word
double dissociation paradox between R.M and C.K
- cases where imagery and perception are affected differently by brain damage provides evidence for double dissociation between imagery and perception which usually indicates that the two functions are served by different mechanisms - double dissocaiation between imagery and perception contradicts evidence that shows that imagery and perception share mechanisms
LeBihan et al. (1993)
- overlap in brain activation - visual cortex
Differences in experience
- perception is automatic and stable - imagery takes effort and fragile
Kossyln's mental scanning experiment
- task: asked subjects to memorize a picture of an island that contained 7 different locations, and then create an image of that island in their mind and focus on one location of the island -subjects were then asked to scan the mental image between every possible pair of locations (21) and affirmed outloud when they arrived at that location in their mental image - result: it took longer to scan between greater distances which supports the idea that imagery is spatial in nature (started the imagery debate) - subjects were then asked
Harvey's explanation: imagery can decrease food craving
- the phonological loop (processes visual and auditory information) is involved in creating auditory images and the visuospatial sketchpad (visual and spatial info) is involved in creating the visual images - the non food visual imagery uses some of the capacity of the visuospatial sketchpad so food related imagery is reduced -the smaller effect for auditory imagery occurs b/c auditory images would affect the phonological loop but not the visuospatial sketchpad
mental scanning
- there is a spatial coorespondance between imagery and perception - Kossyln: created a task in which subjects create mental images and then scan them in their minds
mental chronometry
- used to infer cognitive processes - determing the amount of time needed to carry out various cognitive tasks ex. subjects saw pictures and had to indicate as quickly as possible whether the pictures were of the same or different object (different orientation)
Mental-walk task
- we move closer to small animals than to large animals - images are spatial, like perception
explain double dissociation between imagery and perception paradox
-Behrmann: the mechanisms of perception and imagery overlap only partially with the mechanisms for perception being located at both lower and higher visual centers - the mechanism for imagery is located mainly in higher visual centers - according to this idea visual perception involves bottom up processing
C.K and R.M paradox explained (Behrmann)
-C.K's difficulty in percieving is caused by damag early in the processing stream and he can still create images because higher level areas of his brain are intact -R.M's difficulty in creating mental images is caused by damage to higher level areas (where mental images originate) but he can percieve objects b/c areas earlier in the processing stream are still functioning
Imageless-thought debate
-Early Idea about Imagery - is thinking possible without images?
evidence that imagery can cause food craving
-Harvey had female subjects rate their intensity of craving on a 100 point scale and then divided them into two groups - subjects in the visual imagery group were asked to imagine their favorite food - subjects in the holiday imagery group were asked to imagine their favorite holiday - subjects rated their food craving again after their imagery - results: the food imagery task caused a large increase in craving, but the holiday imagery task had no effect
evidence that imagery can decrease food craving
-Harvey: divided subjects in the food imagery group into 2 groups - subjects in the visual imagery group were asked to close their eyes and create images based on visual cues (ex. appearance of a rainbow) - subjects in the auditory imagery group created images based on auditory cues (ex. sound of a telephone ringing) - results: food craving measured before and after these imagery experiences indicate that food craving is reduced following both visual and auditory imagery
imagery neurons
-Kreiman studied patients who electrodes planted in various areas in their medial temporal lobe (hippocampus and amygdala) to determine the source of severe epiliectic seizures - found neurons that responded to some objects but not to others ex. a neuron responds to a baseball but not a picture of a face - imagery neurons demonstrate a possible physiological mechanism for imagery - the neurons respond in the same way to perceiving an object and to imagining it which supports the idea of a close relationship between perception and imagery
conceptual peg hypothesis
-Paivo: found that memory for pairs of concrete nouns is better than memory for pairs of abstract nouns - concrete nouns create images that other words can "hang on" to
Case of normal perception but impaired imagery
-R.M had damage to his occipital and parietal lobes -he was able to recognize objects and draw accurate pictures of objects that were placed before him - he was unable to draw objects from memory (a task that recquires imagery) and had trouble answering questions that depend on imagery
unilateral neglect
-caused by damage to the parietal lobes - a patient ignores objects in one half of the visual field (ex. shaving one side of face) - Luzzatti: tested the imagery of a patient with unilateral neglect by asking him to describe things he saw when imagining himself standing at one end of the Piazza del Duomo in Milan (palce he had been before brain damage) - result: patient's responses showed that he neglected the left side of his image
mental walk task
-participants were asked to imagine they were walking toward their mental image of an animal -task: estimate how far away they were from the animal when they began to expierience "overflow" (the image filled the visual field or its edges start becoming fuzzy) -result: subjects had to move closer for small animals (ex. less than a foot for a mouse) than for larger animals (ex. 11ft away for elephant) just as if they were walking toward actual animals - evidence for images being spatial
Unilateral neglect
-patient ignores objects in one half of visual field in perception and imagery (aka left neglect - usually happens on left side of the visual field): damage for right hemisphere
method of loci
-placing images at locations - visualizing items to be remembered in different locations in a mental image of a spatial layout
paired associate learning
-task: subjects are presented with pairs of words (ex. boat-hat or car-house) during a study period and then they are presented during the test period with the first word from each pair - their task is to recall the word that was paired with the first word during the study period
A circular plate rests at the center of a small square table. Around the table are a total of four chairs, one along each side of the square table. A person with unilateral neglect sits down in one of the chairs and eats from the plate. After he is "finished," he moves to the next chair on his right and continues to eat from the plate. Assuming he never moves the plate and he continues with this procedure (moving one chair to the right and eating) how many chairs will he have to sit in to eat all the food on the plate? a. 3 b. 4 c. 2 d. 1
2
Kosslyn interpreted the results of his research on imagery (such as the island experiment) as supporting the idea that the mechanism responsible for imagery involves _______ representation A. spatial B. proposition C. unilateral D. epiphenomenal
A. spatial
Why is visual Imagery Is Useful?
It provides a way of thinking that adds another dimension to purely verbal techniques
Pylyshyn (2003)
Kosslyn's results can be explained by using real world knowledge unconsciously (ex. tacit` knowledge explanation)
What started the imagery debate?
Kossyln's mental scanning experiment
epiphenomenon
Pylyshyn: the spatial experience of mental images is something that accompanies the real mechanism but is not actually part of the mechanism ex. lights flashing as a computure carries out calculations
Which of the following has been used as an argument AGAINST the idea that imagery is spatial in nature? a. Depictive representations b. None of these (they all support the idea that imagery is spatial). c. The results of scanning experiments d. The tacit-knowledge explanation
The tacit-knowledge explanation
method of loci
a method in which things to be remembered are placed at different locations in a mental image of a spatial layout
spatial representation
a representation in which different parts of an image can be described as corresponding to specific locations in space
In explaining the paradox that imagery and perception exhibit a double dissociation, Behrmann and coworkers suggested that perception necessarily involves ________ processing and imagery starts as a ________ process. a. top-down; top-down b. top-down; bottom-up c. bottom-up; top-down d. bottom-up; bottom-up
bottom-up; top-down
Perky's experiment, in which participants were asked to "project" visual images of common objects onto a screen, showed that: a. there are large individual differences in people's ability to create visual images. b. imagery and perception are two different phenomena. c. creating a visual image can interfere with a perceptual judgment task. d. imagery and perception can interact with one another.
imagery and perception can interact with one another.
Early researchers of imagery (beginning with Aristotle until just prior to the dominance of behaviorism) proposed all of the following ideas EXCEPT: a. imagery is not required for thinking. b. images are one of the three basic elements of consciousness. c. thought is impossible without an image. d. imagery requires a special mechanism.
imagery requires a special mechanism.
depictive representations
representations that are like realistic pictures of an object so that parts of the representation correspond to parts of the object
Ira and his sister are playing "Name that Tune," the object of which is to name the title of the song when given the song's first line. Ira suggests the line "Sleigh bells ring, are you listening?" His sister can't come up with the answer at first, but realizing that the title is often embedded in the lyrics, she tries to sing them silently to herself. She then bursts out "Ah! It's 'Winter Wonderland'!" It is most likely that Ira's sister used ________ in playing the game. a. inner audition b. mental chronometry c. visual imagery d. mental synthesis
inner audition
Pylyshyn's objection to spatial representation
just because we experience imagery as spatial does not mean that the underlying representation is spatial
Kosslyn's island experiment used the ________ procedure. a. priming b. mental scanning c. mental walk d. categorization
mental scanning
visual imagery
seeing in the absence of a visual stimulus
The mental simulation approach for solving mechanical problems is analogous to the idea that visual imagery involves ________ representations. a. verbal b. propositional c. symbolic d. spatial
spatial
Shepard and Metzler's "image rotation" experiment was so influential and important to the study of cognition because it demonstrated: a. that humans cannot successfully rotate mental images beyond 90 degrees. b. that humans can only perform mental rotation on "real-world" objects. c. that imagery and perception may share the same mechanisms. d. how easy mental rotation is for humans.
that imagery and perception may share the same mechanisms.
mental imagery
the ability to recreate the sensory world in the absence of physical stimuli and occurs in senses other than vision ex. taste, smell, tactile experience
Imagery and the Brain
• Category-specific neurons • Imagery neurons respond to both perceiving and imaging an object - overlap in brain activation - visual cortex
Imagery and the Cognitive Revolution
• Developed ways to measure behavior that could be used to infer cognitive processes • paired associate learning
Paivio (1963, 1965)
• Memory for words that evoke mental images is better than those that do not • Conceptual-peg hypothesis
Shepard and Meltzer (1971)
• Mental chronometry • Participants mentally rotated one object to see if it matched another object
Spatial correspondence between imagery and perception
• Mental scanning • We act as if our mental images are physical entities
Comparing Imagery and Perception
• Relationship between viewing distance and ability to perceive details -Kosslyn (1978): imagine small animal next to large animal - quicker to detect details on the larger animal • Mental-walk task
Is Imagery Spatial or Propositional? Pylyshyn (1973)
• Spatial representation is an epiphenomenon - accompanies real mechanism but is not actually a part of it • Proposed that imagery is propositional - it can be represented by abstract symbols • Imagery debate • Proposition representation: symbols, language • Spatial representation: pictures
Chalmers and Reisberg (1985)
• Task: Had participants create mental images of ambiguous figures • Result: it is difficult to flip from one perception to another while holding a mental image of it
Kosslyn (1973)
• Task: Memorize picture, create an image of it and In the image, move from one part of the picture to another • Result: it took longer for ps to mentally move longer distances than shorter distances • Implication: like perception, imagery is spatial
Lea (1975)
• Task: Memorize picture, create an image of it and In the image, move from one part of the picture to another • more distractions when scanning longer distances may have increased reaction time
Finke and Pinker (1982)
• Task: Participants judge whether arrow points to dots previously seen • Result: longer reaction time when greater distance between arrow and dot (as if they were mentally "travelling") • not instructed to use visual imagery • no time to memorize, and no tacit knowledge
Kosslyn et al. (1978)
• Task: Study figure of island with 7 locations, 21 trips • Results: it took longer to scan between greater distances • Implication: visual imagery is spatial
Using Imagery to Improve Memory
• Visualizing interacting images • Method of loci • Pegword technique
Paired-associate learning
• boat - hat truth - hat • fill in boat - truth ____ • words such as calendar (stimulus) and shoe (response) may be paired, and when the learner is prompted with the stimulus, he responds with the appropriate word (shoe).
Conceptual-peg hypothesis
• concrete nouns create images that other words can hang onto, and that this enhances memory for these words.
