Chapter 10 - Visual Imagery Flashcards
visual imagery
seeing in the absence of visual stimulus
mental imagery
refers to the ability ti recreate the sensory world in the absence of physical stimuli , is used to include all of these senses
How is visual imagery useful?
Provides a way of thinking that adds another
dimension to purely verbal techniques usually associated with thinking
imageless thought debate
• Thought is impossible without images (Aristotle)
• Thought is possible without images
• People who have great difficulty forming visual images
were still quite capable of thinking (Galton, 1983)
paired-associate learning
participants are presented with pairs of words during a study period. asked to recall the word paired with the other
pairs of concrete nouns (easy to visualize) than pairs of abstract nouns
conceptual peg hypothesis
concrete nouns create images that other words can “hang onto”
How did John Watson describe imagery
“unproven” and “mythological”, and
therefore not worthy of study.
Paivio (1963, 1965)
• Memory for pairs of concrete nouns that evoke
mental images is better than those which do not
evoke mental image
• Hotel-student better than Knowledge-honor
• Conceptual-peg hypothesis
• Concrete nouns create images that other words can “hang
onto”
Shepard and Meltzer (1971)
Mental chronometry
• Participants mentally rotated one object to see if it
matched another object
mental chronometry
determining the amount of time needed to carry out a cognitive task
Coglab: Mental Rotation
Data from rotation experiments has been taken to
support that images are rotated in the mind through
a “functional space” - distance is represented in the
image
The greater the degree of rotation required, the
more time needed to complete the rotation
Spatial correspondence between imagery and
perception
- Mental scanning
• Participants create mental images and then scan
them in their minds
Kosslyn (1973)
-Memorize picture, create an image of it
• In image, move from one part of the picture to
another
• It took longer for participants to mentally move long
distances than shorter distances
• Like perception, imagery is spatial
Lea (1975)
• More distractions when scanning longer distances
may have increased reaction time
• Interesting things encountered during the mental
scan are responsible for these distractions
mental scanning
create mental images and then scan them in their minds
imagery debate
about whether imagery is based on spatial mechanisms, such as those involved in perception or on mechanisms related to language, called propositional mechanisms
Kosslyn et al. (1978)
Island with 7 locations, 21 trips
• It took longer to scan between greater distances
• Visual imagery is spatial
Pylyshyn (1973)
Spatial representation is an epiphenomenon
• Accompanies real mechanism but is not actually a
part of it
Proposed that imagery is propositional
• Can be represented by abstract symbols
Pylyshyn (1973)
Imagery debate
• Proposition representation: symbols, language
• Depictive representation: similar to realistic pictures
• Proposition representation:
symbols, language
-representations in which relationships can be represented by abstract symbols, such as an equation, or a statement, such as the cat is under the table
• Depictive representation:
similar to realistic pictures
spatial representations
representations in which different parts of an image can be described as corresponding to specific locations in space
Mental walk task
they were to imagine that they were walking toward their mental image of an animal
Pylyshyn (2003)
- Kosslyn’s results can be explained by using real
word knowledge unconsciously
• Tacit-knowledge explanation
• People know that in real world it takes longer to travel
longer distances, so they simulate this result in Kosslyn’s
experiment.
Finke and Pinker (1982)
• Participants judge whether arrow points to dots
previously seen
• 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, no tacit knowledge
Size in your visual field result
result provides further proof that images are spatial, just like perception
Interactions of imagery and perception
-they can both affect one another
Finke and Pinker (1982)
Participants did not have time to memorize the
distance so they did not have tacit knowledge
Comparing Imagery and Perception
Relationship between viewing distance and ability
to perceive details
• Imagine small object next to large object
• Quicker to detect details on the larger object
Mental-walk task
- Move closer for small animals than for large animals
in order that the animal fills the visual field
• move toward until the elephant (or the mouse) fills the
visual field. Tell the distance to the animals.
• distance to mouse is shorter.
• Images are spatial, like perception
Perky (1910)
• Mistake actual picture for a mental image
• Perky projected a dim image of a banana onto the
screen.
• When participants were asked to reported their
image of banana, their description matched the
images that Perky was projecting (for example, the
orientation of the banana).
-Mistake actual picture for a mental image
Imagery neurons respond to both
perceiving and
imagining an object
• Overlap in brain activation
• Visual cortex
Imagery neurons
respond to some images, but not to others. rate of firing
Why was the discovery imagery neurons important
demonstrates possible physiological mechanism for imagery and because these neurons respond in the same way to perceiving an object and to imagining it, thereby supporting a close relation between perception and imagery
Le Bihan et al. (1993)
Overlap in brain activation
• Visual cortex
Ganis and coworkers (2004)
• Complete overlap of activation by perception and
imagery in front of the brain
• Differences near back of the brain
Amedi and coworkers (2005)
- Again, overlap
• Deactivation of non-visual areas of brain
• Hearing
• Touch
• Mental images more fragile, less activation keeps
other things from interfering
Multi-voxel pattern analysis
-to train a classifier to associate a pattern of voxel activation with particular stimuli
results showed a 55% accuracy when participants imagined the scene
Brain activity in response to imagery
• may indicate something is happening
• may not cause imagery so still we do not know
whether imagery is spatial or propositional.
Transcranial Magnetic Stimulation (TMS) and perception/imagery
• Decreases brain functioning in a particular area of
the brain for a short time
• If behavior is disrupted, the deactivated part of the
brain is causing that behavior
based on the findings, concluded that brain activity in the visual cortex plays a casual role in both perception and imagery
Kosslyn and coworkers (1999)
• TMS to visual area of brain during perception and
imagery task
• Response time slower for both
• Brain activity in visual area of brain plays a causal
role for both perception and imagery
Neuropsychological Case Studies
Removing part of visual cortex reduced the size
of field of view and accordingly decreased the
(walking) distance to the imagery in the mental-walk task (but longer distance to the imagery)
(Farah et al., 1992).
This result supports the idea that the visual
cortex is important for imagery.
Unilateral neglect
• Patient ignores objects in one half of visual field in
perception and imagery, even to the extent of shaving just one side of his face or eating only half the food on one side of the plate
Guariglia and coworkers (1993)
• Brain damage left patient’s perceptions intact but
mental images were not (lesion to the right frontal
lobe)
• No neglect in perception but neglect in mental
images
R.M. (Farah et al., 1988)
Damage to occipital and parietal lobes
• Could draw accurate pictures of objects in front of
him
• Could not draw accurate pictures of objects from
memory (using imagery)
• Could not answer questions based on imagery.
Grapefruit is larger than orange?
C.K. (Behrmann et al., 1994)
• Inability to name pictures of objects, even his own
drawings, in front of him
• He could draw objects in great detail from memory
(using imagery) given the names given verbally
• Could compare sizes, could describe colours of
objects
Evidence for a double dissociation between
imagery and perception
• Indicates separate mechanisms
Also evidence for shared mechanisms
Behrmann and coworkers (1994)
• Mechanisms partially overlap
• Visual perception involves bottom-up processing;
located at lower and higher visual centers
• Imagery is a top-down process; located at higher
visual centers
• Explains C.K. and R.M. but not M.G.S.
Conclusions from the imagery debate
Imagery and perception are closely related and share some (but not all) mechanisms (parallels and interactions).
Differences in experience
- Perception is automatic and stable
* Imagery takes effort and is fragile
Chalmers and Reisberg (1985)
• Had participants create mental images of
ambiguous figures
• Difficult to flip from one perception to another while
holding a mental image of it
Using Imagery to Improve Memory
Placing images at locations
Method of loci
• Visualizing items to be remembered in different locations in a mental image of a spatial layout
Using Imagery to Improve Memory
Associating images with words
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
Coglab: Link Word
The link word method (e.g., Atkinson & Raugh,
1975) is a way of associating or linking two words
together. It is based on the finding that when people
form an interactive image between two concepts,
one item becomes an excellent cue for retrieving
the second item.
What do we predict participants will do? Why?
People should recall quite a large number of
meanings if they truly did spend about 10 seconds
considering their interactive image. The reason is
that the French word should serve as a good cue
for the image, and the image serves as a link to the
English meaning.
Spatial imagery people better
in mental rotation
Object imagery people better
in degraded picture
task
spatial imagery refers to
the ability to image spatial relations, such as the layout of a garden
object imagery refers to
the ability to image visual details, features, objects, such as a rose bush with bright roses in the garden
