CHAPER 10 QUESTIONS

links between imagery and perception: mental scanning tasks

imagery shared the same mechanisms as perception in some experiments. Visual imagery is spatial in nature parellels: -size in the visual field -interaction bw perception and imagery -physiological experiments

Behrmann's top-down vs. bottom-up explanation for imagery vs. perception

Behrmann said that the mechanisms of perception and imagery overlap only partially, with the mechanism for perception being located at both lower and higher visual centers and the mechanisms for imagery being located mainly in higher visual centers. According to this idea, visual perception necessarily involves bottom-up processing, which starts when light enters eye...

criticism of kosslyns work

Pylyshyn stated that imagery is based on a mechanism related to language (it creates a propositional representation in a person's mind). One of his arguments is the tacit knowledge explanation

dissociations between imagery and perception: RM

RM suffered damage to parietal and occipital lobes. Was able to recognize and draw accurate pictures of objects placed before him; however, was unable to draw objects from memory, which is a task that requires imagery.

mental walk tasks

Subjects are to imagine that they are walking toward their mental image of an animal. Their task is to estimate how far away they were from the animal when they began to experience "overflow"- when the image filled the visual field or when its edges started becoming fuzzy

Pylyshyn vs Kosslyn: spatial representations vs propositional representation

imagery debate. Pylyshyn stated that imagery is based on a mechanism related to language (it creates a propositional representation in a person's mind). One of his arguments is the tacit knowledge explanation

Overlap/differences of activation in brain for imagery and perception

-Ganin's erxperiment shows actication at 3 different locations in the brain that perceptiona nd imagery activate the same areas in the frontal lobe, but there is some difference near the back brain because of activation of the visual cortex. -Amedi showed in an fMRI experiment that it showed overlap, but saw that when subjects were using visual imagery, hearing and sound were deactivated, so during imagery, their activation was decreased.

dissociations between imagery and perception: CK

CK was a 33 yr old graduate student struck by a car while jogging. Suffered from visual agnosia= the inability to recognize objects. Could not recognize parts that make things into a meaningful whole. However, was able to draw things from memory, a task that depends on imagery. He was still unable to identify objects that were drawn

Kosslyn's early work: boat and island example

Kosslyn asked subjects to memorize a picture of the boat, and then to create an image of that object in their mind and to focus on one oart of the boat, such as the anchor. They were then asked to look for another part of the boat, such as the motor, and press the "true" botton when they found this part or the "false" button whhen they wouldnt find it. Also did island experiment in which subjects were told to imagine an island that contained 7 different locations. By having subjects scan bw every possible pair of locations, he determined the relationship between reaction time and distance shown. Just like boat experiment, it took longer to scan between greater distances in the image, which supports the result that visual imagery is spatial in nature

TMS studies, unilateral neglect studies

Kosslyn did experiment using transcranial magnetic stimulation to the visual cortex while subjects were carrying out either perception task ot imagery task. For perception, subjects were presented briefly a display and were asked to make judgments about the stripes in the 2 quadrants. K measured their reaction times to make the judgment with one control group without TMS and one with. Results were that stimulation caused subjects to respond more slowly, and that this slowing effect occurs for both perception and imagery. He concluded that the brain activation that occurs in response to imagery is not an epiphenomenon and that brain activity in the visual cortex plays a causal tole in both perception and imagery

tacit knowledge explanation

One of his arguments is the tacit knowledge explanation, which states that when asked to imagine something, people ask themselves what it would look like to see it and then stimulate this staged event. Subjects unconsciously use knowledge about the world in making their judgments

Paivio's conceptual peg hypothesis: concrete vs abstract words

Paivio said that it was easier to remember concrete nouns/words (tree,truck) that can be imagined than it is to remember absract nounds/words (truth, justice) that are difficult to imagine According to his "conceptual peg hypothesis", concrete nouns create images that other words can hang onto.

dissociations between imagery and perception: M.G.S.,

Patient MGS was young woman who was about to remove part of occipital lobe bc of severe epilepsy. Before surgery, MGS was told to perform mental walk task and stop walking when became fuzzy. Before surgery, she was about 15 feet away from animal. After the surgery, her distance from the horse was at 35 feet. This occurred because removing part of her visual cortex reduced her field of view size. This supports the idea that the visual cortex is important for imagery

What are the typical results of mental rotation experiments

Shepard and Metzler did mental chronometry (determining the amount of time needed to carry out various cognitive tasks)and subjects tasks were to determine if 2 objects were the same or not. Results showed that the time it took to decide that 2 views were of the same object was directly related to how different the angles were between the 2 views. showed that visual imagery is spatial

Imagery in the brain: neurons that respond to BOTH imagery and perception of an object

imagery neurons are neurons that fire the same way when thinking of an object and looking at the object

mental imagery vs visual imagery

visual imagery- seeing in the absence of a visual stimulus. Seeing a book at home right where you left it when you forgot it for class. mental imagery- experiencing sensory impression in the absence of a visual stimulus. Can imagine tastes, smells, and tactile experiences