Visual Imagery Flashcards
Mental Imagery
Experiencing a sensory impression in the absence of a sensory input
or
The ability to re-create the sensory world in the absence of a physical stimuli
i. e. tasting food, hearing musics
- Imagining tastes, smells, and tactile experiences
Visual Imagery
Seeing in the absence of a visual stimulus
Imageless thought debate
“Thought is impossible without an image” -Aristotle
Paired-associate learning (Paivio)
It is easier to remember concrete nouns such as “truck” or “tree” then it is to remember abstract nouns such as “truth” or “justice” that are difficult to image.
-Memory for pairs of concrete nouns is better than memory for pairs of abstract nouns
Shepard and Meltzer Experiment
Mental Rotation
- Mentally compared two objects to see if they were the same or different
- They inferred cognitive processes by measuring mental chronometry
What were the IV and DV of the Mental Rotation Coglbb?
IV = object similarity (same or different) and rotation angle
DV = RT (milliseconds)
-RT from the correct trials were only recorded
Why was the mental rotation important in imagery?
It was one of the first studies to apply quantitative methods to the study of imagery and suggest that imagery and perception share the same mechanisms (i.e. mental mechanisms- manipulating perceptual and mental images, and brain mechanism- such as which structures are involved in creating the perceptual and mental images)
What did Shepard and Metzler’s study should about the mental and perceptual images?
That they both involve a spatial representation of the stimulus
Mental Rotation: Which will have a longer RT and why? Same and 90° or same and 180°
Same and 180° because you will have to rotate it for longer and thus have a longer RT
What is different about how you mentally rotate it the object in the different rotation condition?
You will mentally rotate it such that it should match up with the other condition. However, once you meet max rotation and realize that the two letters are a mirror image of each other, then you will report that they are different.
How does your RT change in the “same” condition in the mental rotation lab?
The further you have to mentally rotate the object, the longer your RT will be.
How does your RT change for the symbolic representation (block by block analysis) in the Mental Rotation Lab?
For the same and different condition they will be the exact same RT because you are just working working your way down the blocks one by one until you find an area where it might be different.
What are the mental processes involved when the shapes are the same? (0° vs 120°)
0° = 1. Perceive the objects
- Compare the objects
- Respond
- -> No rotation is required
120° =
- Perceive the objects
- Compare and rotate/rotate and compare
- When you reach 120° you stop and compare
- Respond
What did the Shepard and Meltzer experiment show?
The time it takes to determine that the two objects are the same is directly related to the difference in the angles between the two objects.
-As if we “mentally rotate” one object to match the other object
Describe Kosslyn (1973) Experiment
Participants memorized a picture, and were asked to create a mental image of it. They then had to move from one part of the picture to another.
Results of Kosslyn (1973) Experiment
It took longer for participants to mentally move longer distances than shorter distances
Conclusion: Like perception, imagery is spatial
What was the argument Lea (1975) had about Kosslyn’s experiment?
-That an increase in RT was due to more distractions when scanning longer distances
Which experiment is “mental scanning” associated with?
Kosslyn (1973)
Which experiment is “mental chronometry” associated with?
Shepard and Metzler’s experiment
Describe the experiment conducted by Kosslyn (1978) in the efforts to address Lea’s (1975) argument?
Had participants construct an island with 7 locations and 21 trips.
Results: It took longer to scan between greater distances
-Therefore it was determined that visual imagery is spatial.
–> More about the distance and not the intervening objects
Pylyshyn (1973) experiment “Imagery Debate”
A debate about whether imagery is spatial (i.e. like those involved in perception) or propositional (i.e. mechanisms related to language)
Spatial representations
Representations in which different parts of an image can be described as corresponding to specific locations in space.
Describe the argument between Kosslyn and Pylyshyn.
Kosslyn argued that imagery was spatial in nature where as Pylyshyn disagreed saying that just because we experience imagery as spatial doesn’t mean that the underlying representation is spatial
Epiphenomenon
Pylyshyn argues that spatial experience of mental images is an epiphenomenon (something that accompanies the real mechanism (i.e. spatial) but is not actually part of the mechanism (i.e. spatial))
Propositional
Pylyshyn proposed that imagery is propositional because it can be represented by abstract symbols.
Depictive representation
Spatial representations in which parts of the representation correspond to parts of the object.
What is the relationship between Pylyshyn’s propositional representation of the boat, and RT?
The further you have to travel (i.e. links), the longer your RT will be
Pylyshyn (1973) “Tacit-knowledge explanation”
Kosslyn’s (1978) results can be explained by using real-world knowledge unconsciously (i.e. because we know that if you look at a map and the further something is on the map, the longer it will take for you to travel there)
Finke and Pinker (1982)
They were shown a series of dots, then they were removed (they weren’t allowed to memorize the dots).
A arrow then showed up in a certain location and they were required to state whether the arrow was pointing to the correct location of one of the dots.
Results: The further the distance the arrow was away from the dot, the longer the RT
-Thus, because there was no time to memorize, there was no use of tacit knowledge.
Kosslyn’s experiment w/ the elephant, fly, and rabbit.
Relationship between viewing distance and the ability to perceive details.
-Imagined a small animal next to a large animal
“Does the rabbit have whiskers?”
-Quicker to detect details on the larger animal (i.e. when the rabbit filled more of the participants visual field
How would the results differ if you imagined the animal in a propostional representation?
The RT would be the same for both animals because you are just going through the representation (i.e. abstract language) to determine whether the rabbit had whiskers or not.
Describe Perky’s experiment (1910)
- Researchers displayed a very faint picture of a banana on a screen (they did this from behind the screen so participants didn’t know it was on the screen).
- Participants were then asked to imagine a banana on the screen, then describe what it looked like.
Results:
The peoples description of the banana tended to look exactly like what was on the screen, even though they weren’t aware of it, but they might be subconsciously perceiving it.
-Confused mental image and perception
What are some experiments that describe interactions of imagery and perception?
If imagery affects perception and perceptional affects imagery, this means that imagery and perception both have access to the same mechanisms.
- Perky’s (1910) experiment
- Farah (1985)
Describe Farah (1985) experiment
- Participants imagined either an H or a T on the screen.
- They were then shown two different screens, and one contained the stimulus (i.e. either an H or a T)
- Participants had to report which screen they saw the stimulus in
- The target letter was detected more accurately when the participant imagined the same letter as the target letter rather than a different one.
–> Shows that perception and imagery share mechanisms
Imagery and the brain
Kreiman (2000) -Baseball and face example
- Single cell recording in humans
- Patients being treated for severe epilepsy
- Recorded from MEDIAL TEMPORAL LOBES
–> Showed participants pictures of objects and had them imagine these same objects
What were the results of the Kreiman (2000) experiment?
-We have category-specific neurons that respond to a particular object (i.e. baseball) but not the other (i.e. face) and vice versa.
- It was found that the neurons in the medial temporal lobe fired when perceiving the baseball as well as imagining it.
- -> Known as imagery neurons (however, these neurons did not respond to the face)
- Neurons respond in the same way to perceiving an object and to imagining it
- -> Close relation between perception and imagery
Describe the experiment by LeBihan (1993)
-They demonstrated the both perception and imagery activate the primary visual cortex
–> i.e. by perceiving an image and then imaging it
What generates a greater response in the visual cortex, asking “is the green of the trees darker than the green of the grass?” or by asking a nonimagery question such as “is the intensity of electrical current measured in amperes?”
Asking an imagery question “is the green of the trees darker than the green of the grass?”
Ganis and coworkers experiment (i.e. about the tree)
2 Conditions: Perception and imagery
Perception
- Saw a tree
- Heard the word tree
- Heard a sound of a letter (i.e. W)
- Had to judge if the tree is wider than it is tall
Imagery
-Told to imagine a picture they studied before when they heard the tone (i.e. tree)
- Heard a “W”
- Then asked to judge if the tree was wider than it is tall
Results of Ganis and coworkers experiment (i.e. about the tree)
Frontal lobe: activity is the same for both perception and imagery
Middle of the brain: shows same activity for both perception and imagery
Occipital lobe (in the visual cortex): perception activates more of this area of the brain than does imagery
Kosslyn (1999) -Transcranial Magnetic Stimulation (TMS)
Stimulated parts of the visual cortex during perception and imagery tasks
Perception condition: Participants were asked to view a display and then asked to make a judgement about the stripes in the two quadrants (i.e. are the stripes in quadrant 3 longer than the stripes in quadrant 2)
- They were allowed to look at the stripes while answering the questions
Imagery condition: Participants did the same thing except when asked to answer questions they had to close their eyes and base their judgements on their mental image of the display.
What did Kosslyn measure in the TMS experiment?
Measured RT to make a judgement both when TMS was applied to the visual area, and in the control condition when the stimulation was directed to another part of the brain
What were the results of Kosslyn’s TMS experiment?
Participants responded slower if stimulation was applied (this slowing effect occurred both for perception and for imagery)
-Suggest that the visual cortex plays a causal role in both perception and imagery
Mental Walk task (Farah)
*Did this test before and after the operation of the removal of part of her right occipital lobe
Used patient M.G.S - had the participant mentally walk as close as possible until the horse took up her whole visual field
What did Kosslyn measure in the TMS experiment?
Measured RT to make a judgement both when TMS was applied to the visual area, and in the control condition when the stimulation was directed to another part of the brain
What were the results of Kosslyn’s TMS experiment?
Participants responded slower if stimulation was applied (this slowing effect occurred both for perception and for imagery)
-Suggest that the visual cortex plays a causal role in both perception and imagery
Mental Walk task (Farah)
*Did this test before and after the operation of the removal of part of her right occipital lobe
Used patient M.G.S - had the participant mentally walk as close as possible until the horse took up her whole visual field
Why does removing part of the patient M.G.S right occipital lobe cause her to be mentally further away from the horse before it fills up her visual field?
Because when you remove part of the right occipital lobe, it decreases the size of the patients visual field. Therefore, they can be further away before the object fills their visual field.
-This supports the idea that the visual cortex is is important for imagery.
What is unilateral neglect?
-Patient ignores objects in one half of visual field
What can happen when you have damage to the parietal lobes?
It can cause a condition called unilateral neglect.
Describe the experiment by Bisiach and Luzzatti
When the patient with damage to his parietal lobe imaging himself standing at a familiar place in italy at one end of the square before his brain was damaged, he neglected the left side of his mental image, just as he neglected the left side of his perceptions.
- He neglected his left side by only describing things on his right.
- He did the same thing in position B when at the other end of the square.
Describe the study by Guarglia et al. (1993)
-Studied a patient with brain damage
- Perceptions intact
- Mental images were impaired (his mental images were limited to only one side like the Italy example in the square)
- -> Unilateral neglect
Describe the study by Farah et al. (1998) about patient R.M.
- Damage to occipital and parietal lobes
- Could draw accurate . pictures in front of him
- Could not draw accurate pictures of objects from memory (using imagery)
–> Intact on perception, impaired on imagery
Behrmann (1994) study on patient C.K.
- Struck by a car while jogging
- Suffered from visual agnosia (the ability to visually recognize objects)
- Could recognize parts of objects but couldn’t integrate them into a meaningful whole.
- He was able to draw objects from memory (using imagery)
