Chapter 10-Visual imagery Pt.1 Flashcards
Visual imagery
“Seeing” in the absence of a visual stimulus
Mental imagery
Experiencing a sensory impression in the absence of a sensory input
Why is visual imagery useful
Provides a way of thinking that adds another dimension to purely verbal techniques
Imageless-thought debate
- thought is impossible without image (Aristotle)
- thought is possible without images (people who have great difficulty forming visual images were still capable of thinking-Galton)
Imagery and behaviourism
Developed ways to measure behaviour that could be used to infer cognitive processes
-paired-associate learning
How does John Watson describe images
As unproven and mythological and therefore not worthy of study
Paivio
-memory for pairs of concrete nouns that evoke mental images is better than those which do not evoke mental images
conceptual-peg hypothesis: concrete nouns can create images that other words can “hang from”
Shepard and Meltzer
Mental chronometry (rotation)
Participants mentally rotated one object to see if it matched another object
Pair A match (picture plane pairs)
Pair B match (depth pairs)
Pair C do not match
Coglab: mental rotation
- Judge whether objects are identical
- half the time they were, other half were mirror objects
- time taken to make a judgement increased as angle of rotation between the objects increased
Kosslyn mental scanning
- memorize picture, create mental image of it (boat)
- in image, move from one part of the picture to another
- took longer for participants to mentally move long distances than shorter distances
- like perception, imagery is spatial
Lea
Critique to mental scanning
More distractions when scanning longer distances may have increased reaction time
Kosslyn et al. Response to lea
- island with 7 locations and 21 trips (no distractions in between)
- it took longer to scan between greater distances
- visual imagery is spatial
Pylyshyn
Spatial representation is an epiphenomenon
-accompanies real mechanisms but is not actually a part of it
Proposed that imagery is propositional
-can be represented by abstract symbols, language
Imagery debate
Between:
Propositional representation: symbols, language
And
Depictive representation: similar to realistic pictures
Tacit knowledge explanation
Proposed by Pylyshyn in response to Kosslyns island experiment
States that results can be explained using real world knowledge unconsciously
People know that in real world it takes longer to travel longer distances, so they stimulate this result in Kosslyns experiment
Finke and Pinker (arrow experiment)
Participants judge whether arrow points to dots previously seen
Longer reaction time when greater distance between arrow and dot (as they were “mentally” travelling)
Not instructed to use visual imagery
No time to memorize, no tacit knowledge
Relationship between viewing distance and ability to perceive details
Quicker to detect details on larger object
E.g. elephant next to rabbit and then rabbit next to fly
Mental walk task
participants had to move toward animal until it field their visual field and then tell distance to the animals
Move closer for small animals than for large animals so that the animal fills your visual field
Therefore if comparing elephant and mouse, your distance to mouse is shorter
Proves that images are spatial like perception
Perky (perception influencing imagery)
Mistake actual picture for mental image
Projected a dim image of a banana onto the screen
When participants were asked to report their image of the banana, their description matched the images that Perky was projecting
Farrah’s letter visualization experiment (imagery can influence perception)
- Subject visualizes an H or a T on the screen
- Two squares flash one after another and the target letter can be in either square
- Their accuracy was higher when the target letter was the same as the one they had been imagining
Imagery and the brain
Imagery neurons respond to both perceiving and imagining an object
- overlap in brain activation
- visual cortex
Le Bihan et al
Study measuring brain activity using fMRI
Activity increases to presentation of a visual stimulus
And also increases when subjects are imagining the stimulus
Activity low when there is no actual or imagined stimulus
Ganis and coworkers
Complete overlap of brain activation by perception and imagery in front of the brain
Differences near back of brain
Participants would hear the name of an object previously studied. In the imagery condition they had their eyes closed and have to imagine it. In the perception condition, subjects saw a faint picture of the object. Would hear “W” and had to report on whether it is “wider than tall”
