PSYC 230 Chapter 10

Paired-associate learning

A learning task in which participants are first presented with pairs of words, then one word of each pair is presented and the task is to recall the other word

Suppose we ask people to perform the following cognitive tasks. Which is LEAST likely to strongly activate the visual cortex? A. Imagine the meaning of the word "ethics." B. Imagine your car first from far away and then how it looks as you walk closer to it. C. Imagine a tic-tac-toe game proceeding from start to finish. D. Imagine a typical unsharpened pencil. Approximate its length in inches.

A. Imagine the meaning of the word "ethics."

Patient M.G.S.

She had part of her right occipital lobe removed. Removing part of the visual cortex reduced the size of her field of view, so the horse filled up the field when she was farther away. This result supports the idea that the visual cortex is important for imagery

Mental chronometry

amount of time needed to carry out cognitive task (--> infer cognitive process!)

Perky's experiment, in which participants were asked to "project" visual images of common objects onto a screen, showed that A. imagery and perception are two different phenomena. B. imagery and perception can interact with one another. C. there are large individual differences in people's ability to create visual images. D. creating a visual image can interfere with a perceptual judgment task.

B. imagery and perception can interact with one another.

Ganis et al. (2004): overlap vs. differences

Complete overlap of activation by perception and imagery in front of the brain Differences near back of the brain

R.M. (Farah et al., 1988)

Damage to occipital & parietal lobes (probably more parietal) Could draw accurate pictures of objects in front of him Could not draw accurate pictures of objects from memory (a task that requires imagery), or respond to questions that depend on imagery "Is a grapefruit larger than an orange?"

Transcranial magnetic stimulation (TMS)

Decreases/increases brain functioning in a particular area for a short time If behavior is disrupted, the deactivated part of the brain is causing that behavior

Mental imagery

Experiencing sensory impression in absence of sensory input --Images --Tastes (imagine tasting your favorite food) --Sounds (imagine the tune of your favorite song)

C.K. (Behrmann et al., 1994)

Hit by car while jogging Probably occipital damage Visual agnosia: could not name pictures of objects, even his own drawings, in front of him Could draw objects in great detail from memory (using imagery) --> perception impaired, imagery relatively normal

Paivio (1963, 1965)

Memory for words that evoke mental images (concrete words) is better than those that do not (abstract words)

Farah (1985)

Participants visualize letter H or T on screen Two squares flash: target letter either first or second Task: Was target letter flashed on first or second square? Quicker to respond if had imagined the same letter as the one shown --> perception and imagery share mechanisms

Imagery debate - imagery is either:

Proposition representation: symbols, language (Pylyshyn) Depictive/Spatial representation: similar to realistic pictures (Kosslyn)

Why is Visual Imagery useful?

Provides a way of thinking that adds another dimension to purely verbal techniques

Kosslyn et al. (1995): Visual cortex is organized as a topographical map

Specific locations on a visual stimulus cause activity at specific locations in the visual cortex Points near each other on the stimulus cause activity at locations near each other on the cortex Looking at a small object causes activity in the back of the visual cortex (green); larger objects cause activity to spread forward (red) Imagining small objects (circle), medium objects (square), large objects (triangle) follows same pattern as perception

In Kosslyn et al., 1999, transcranial magnetic stimulation (TMS)

TMS to visual cortex during perception or imagery task Answered questions about stimuli while viewing (perception) or with eyes closed (imagining) Response time slower for both taskswhen stimulation applied Brain activity in visual cortex plays a causal role for both perception and imagery

Francis Galton (1883) asked people to introspect about images, and used self-report data to conclude that people tend to:

view images from a perspective inspect images similarly to inspecting a picture "see" some details easier than others there are individual differences Galton claimed that scientists had very weak visual imagery!! So maybe imagery isn't always required for thinking...

Imagery neurons

respond to both perceiving and imagining an object Category-specific neurons in the medial temporal lobe (single-neuron recordings (rare), Kreiman et al., 2000) Respond to some objects but not others Fire in the same way when seeing vs. imagining

Visual imagery

seeing in the absence of a visual stimulus

Stephen Kosslyn (1973): Mental scanning

A process of mental imagery in which a person scans a mental image in his or her mind Mental map experiment, found correlation between distance on map and amount of time to mentally scan

Mental walk task

A task used in imagery experiments in which participants are asked to form a mental image of an object and to imagine that they are walking toward this mental image. Have to move closer to small animals than to large animals Images are spatial, like perception

Mental imagery involves A. experiencing a sensory impression in the absence of sensory input. B. mental representations of the current sensory inputs. C. sensory representations of a stimulus. D. the misrepresentation of a stimulus as possessing physical attributes that are, in fact, absent.

A. experiencing a sensory impression in the absence of sensory input.

The "imagery debate" is concerned with whether imagery A. is based on spatial or language mechanisms. B. is identical for all people. C. actually exists. D. can be used to inform non-visual sensory systems.

A. is based on spatial or language mechanisms.

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

Imagery and perception share mechanisms:

It takes longer to answer questions about small details in a mental picture (Kosslyn, 1976) Visualizing a stimulus makes it easier to perceive the actual stimulus later (Farah, 1985) Similar neural areas involved in both visual perception and visual imagery (e.g., Farah, 1988)

Pylyshyn (2003) - tacit knowledge explanation

Kosslyn's results can be explained by using real-word knowledge unconsciously One reason that scanning time increases as the distance between two points on an image increases is that subjects are responding to Kosslyn's tasks based on what they know about what usually happens when they are looking at a real scene We know that in the real world it takes longer to travel longer distances

Kosslyn (1978): Mental Maps Experiment

Look at a picture, memorize it, create an image of it In image, move from one part of the picture to another Respond True or False about locations Took longer for participants to mentally move long distances than short distances Like perception, imagery is spatial! Results: Imagined distance corresponds to real distance

Behrmann et al. (1994):

Mechanisms of perception and imagery overlap partially Visual perception involves bottom-up processing; located at lower and higher visual centers Imagery originates as a top-down process; located at higher visual centers (memory) Explains C.K. and R.M. but not the case M.G.S. who had parts of her early visual cortex removed and showed changes in both perception and imagery

Lea (1975) different explanation of mental scanning

More distractions when scanning longer distances may have increased reaction time Interesting things encountered during the mental scan are responsible for these distractions

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 "traveling") Not instructed to use visual imagery No time to memorize, no tacit knowledge

Zenon Pylyshyn proposed another explanation to mental scanning

Spatial representation is an epiphenomenon --Accompanies real mechanism but is not actually a part of it --(think: lights on a computer) Proposed that imagery is propositional --Relationships can be represented by abstract symbols (an equation or statement)

Imageless-thought debate

The debate about whether thought is possible in the absence of images

Lee et al. (2012): neural mind reading

Use brain activation patterns to determine what subjects were perceiving or imagining Activity in visual cortex = prediction for perception Activity in higher visual areas = prediction for imagining

Unilateral neglect (hemispatial neglect)

Usually occurs after damage to parietal lobe Patient ignores objects in one half of visual field in perception, also happens for imagery

Method of loci

Visualizing items to be remembered in different locations in a mental image of a spatial layout may help with retrieving memories later

Food craving

intense desire to eat a specific food (beyond just hunger because of intensity and specificity) Most common in Western societies: chocolate Recurring cravings associated with overeating, binge eating May be caused by nutritional deficiencies, hormonal changes, emotions, proximity to enticing foods May also be caused by cognitive factors (including imagery) "I can imagine the taste of it"

Amedi et al. (2005): overlap vs. differences

Again, some overlap for perception and imagery Deactivation of non-visual areas of brain during visual imagery: Hearing, Touch --> Mental images more fragile than real perception, less activation keeps other things from interfering ("quiet down")

Perky (1910)

Asked subjects to "project" a visual image of object onto screen and describe image Perky was actually back-projecting a very dim image of object onto screen Subjects descriptions matched the projected image (even though they didn't notice the actual picture!) Mistaken picture for mental image

Suppose we asked people to form simultaneous images of two or more animals such as a rabbit alongside an elephant. Then, we ask them basic questions about the animals. For example, we might ask if the rabbit has whiskers. Given our knowledge of imagery research, we would expect the fastest response to this question when the rabbit is imagined next to A. a rhinoceros B. a bumblebee C. a wolf D. an anteater

B. a bumblebee

Guariglia et al. (1993)

Brain-damaged patient Patient's perceptions were intact, but mental images were impaired: neglect (mental images limited to one side)

Mental-scanning experiments found A. that imagery does not represent spatial relations in the same way perceptual information does. B. an absence of mental scanning when processing a mental geometric image. C. a direct relationship between scanning time and distance on the image. D. a constant scanning time for all locations on an image.

C. a direct relationship between scanning time and distance on the image.

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. bottom-up; bottom-up B. top-down; top-down C. bottom-up; top-down D. top-down; bottom-up

C. bottom-up; top-down

Conceptual-peg hypothesis:

Concrete nouns can create mental images that other words can "hang onto" Presentation of the paired associate will bring back the mental image for that word, as well as the image that was tied to it during learning

Ganis and coworkers used fMRI to measure brain activation for perception and imagery of objects. Their results showed that A. there is no difference between the activation caused by perception and by imagery. B. perception and imagery activate the same areas near the back of the brain, but imagery activates more of the frontal lobe than does perception. C. perception and imagery activate the same areas of the frontal lobe, but imagery activates more of the back of the brain than perception does. D. perception and imagery activate the same areas of the frontal lobe, but perception activates more of the back of the brain than imagery does.

D. perception and imagery activate the same areas of the frontal lobe, but perception activates more of the back of the brain than imagery does.

Relationship between viewing distance and ability to perceive details (Kosslyn, 1978)

Imagine small object next to large object Quicker to detect details on the larger object Imagine two animals next to each other: elephant and rabbit Elephant fills most of visual field "Does the rabbit have whiskers?" Imagine two animals: rabbit and mouse Now rabbit fills most of visual field RT to rabbit question: answer faster when it filled more of the visual field