Psychology 317 Chapter 10: Visual Imagery

Imagery and the Cognitive Revolution

- Developed ways to measure behavior that could be used to infer cognitive processes -- Paired-associate learning - Paivio (1963, 1965) -- Memory for words that evoke mental images is better than for those that do not -- Conceptual peg hypothesis - Shepard and Metzler (1971) -- Mental chronometry

Conceptual peg hypothesis

A hypothesis, associated with Alan Paivio's dual coding theory, that states that concrete nouns create images that other words can hang on to, which enhances memory for these words

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

Mental chronometry

Determining the amount of time needed to carry out a cognitive task. Contrasts with the conceptual peg hypothesis - Shepard and Metzlerr (1971)

Martha Farah (1985)

Instructed her participants to imagine either the letter H or the letter T on a screen. One of the squares contained a target letter, which was either an H or a T. The participants' task was to indicate whether the letter was in the first square or the second one. The target letter was detected more accurately when the participant had been imagining the same letter rather than the different letter; perception and imagery share mechanisms

Stephen Kosslyn and coworkers (1995)

Made use of the way the visual cortex is organized as a topographic map. Looking at a small object causes activity in the back of the visual cortex. Larger objects cause activity to spread forward. Small, medium, and large images cause the most activity in some locations

Imagery neuron

Neurons in the human brain studied by Kreiman, which fire in the same way when a person sees a picture of an object and when a person creates a visual image of the object.

Marlene Behrmann and coworkers (1994)

Studied C.K., a 33-year-old graduate student who was struck by a car as he was jogging.C.K. suffered from visual agnosia, the inability to visually recognize objects. C.K. could recognize parts of objects but couldn't integrate them into a meaningful whole. But despite his inability to name pictures of objects, C.K. was able to draw objects from memory, a task that depends on imagery. When he was shown his own drawings after enough time had passed so he had forgotten the actual drawing experience, he was unable to identify the objects he had drawn.

Spatial imagery

The ability to image spatial relations.

Making Sense of Neuropsychological Results

- Evidence for a double dissociation between imagery and perception -- Indicates separate mechanisms - Also evidence for shared mechanisms

Imagery and the Brain

- Imagery neurons -- Overlap in brain activation -- Visual cortex - Le Bihan and coworkers (1993) - Ganis and coworkers (2004) - Amedi and coworkers (2005) -- Again, overlap -- Deactivation of nonvisual areas of brain --- Hearing, touch -- Mental images more fragile, less activation keeps other things from interfering - Brain activity in response to imagery -- May indicate something is happening -- May not cause imagery - Transcranial magnetic stimulation (TMS) -- 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 - Kosslyn and coworkers (1999)

Using Imagery to Improve Memory

- Placing images at locations - Method of loci - Associating images with words - Pegword technique -- 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

- Spatial correspondence between imagery and perception -- Mental scanning -- Participants create mental images and then scan them in their minds - Kosslyn (1973) - Lea (1975) -- More distractions when scanning longer distances may have increased the reaction time. -- Interesting things encountered during the mental scan are responsible for these distractions. - Kosslyn and coworkers (1978) - Differences in experience -- Perception is automatic and stable -- Imagery takes effort and is fragile - Chalmers and Reisberg (1985)

Pegword technique

A method for remembering things in which the things to be remembered are associated with concrete words.

Method of loci

A method for remembering things in which the things to be remembered are placed at different locations in a mental image of a spatial layout.

Epiphenomenon

A phenomenon that accompanies a mechanism but is not actually part of the mechanism. An example of an epiphenomenon is lights that flash on a mainframe computer as it operates - Spatial representation - Propositional representation In contrast, a spatial representation would involve a spatial layout showing the cat and the table that could be represented in a picture - Depictive representation

Unilateral neglect

A problem caused by brain damage, usually to the right parietal lobe, in which the patient ignores objects in the left half of his or her visual field. - Neuropsychological Case Studies - Edoardo Bisiach and Claudio Luzzatti (1978)

Mental scanning

A process of mental imagery in which a person scans a mental image in his or her mind.

Spatial representation

A representation in which different parts of an image can be described as corresponding to specific locations in space - It is an epiphenomenon -- Accompanies real mechanism but is not actually a part of it

Propositional representation

A representation in which relationships are represented by symbols, as when the words of a language represent objects and the relationships between objects such as an equation, or a statement, such as "The cat is under the table."

Degraded pictures task

A task in which a line drawing is degraded by omitting parts of the drawing and obscuring it with a visual noise pattern. The person's task is to identify the object.

Mental rotation task

A task in which a person judges whether two pictures of three-dimensional geometric objects are pictures of the same object rotated in space or are pictures of two mirror-image objects rotated in space - Spatial imagers did better in the mental rotation task, and object imagers did better on the degraded pictures task, thus providing more evidence distinguishing between spatial and object imagers.

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 - Move closer to small animals than to large animals - Moving closer to an object, such as a car, has two effects: (1) The object fills more of your visual field, and (2) details are easier to see.

Paper folding test (PFT)

A test in which a piece of paper is folded and then pierced by a pencil to create a hole. The task is to determine, from a number of alternatives, where the holes will be on the unfolded piece of paper.

Vividness of visual imagery questionnaire (VVIQ)

A test in which people are asked to rate the vividness of mental images they create. This test is designed to measure object imagery ability

Visual imagery

A type of mental imagery involving vision, in which an image is experienced in the absence of a visual stimulus. - Provides a way of thinking that adds another dimension to purely verbal techniques

Cheves Perky (1910)

Asked her participants to "project" visual images of common objects onto a screen and then to describe these images as she was back-projecting a very dim image of this object onto the screen without them knowing. The participants' descriptions of their images matched the images that she was projecting. Not one of her 24 participants noticed that there was an actual picture on the screen, mistaking it for a mental picture - Interactions of Imagery and Perception - Martha Farah (1985)

Kosslyn (1978)

Asked participants to imagine two animals, such as an elephant and a rabbit, next to each other and to imagine that they were standing close enough so that the larger animal filled most of their visual field. Then they imagined a rabbit and a fly next to each other. Participants answered questions about the rabbit more rapidly when it filled more of the visual field. Participants also had to move closer for small animals than for larger animals; images are spatial, just like perception - Mental walk task

Kosslyn (1973)

Asked participants to memorize a picture of an object, such as a boat and then to create an image of that object in their mind and to focus on one part of the boat, such as the anchor. It took longer for participants to find parts that are located farther from the initial point of focus because they would be scanning across the image of the object. Like perception, imagery is spatial.

Kosslyn and coworkers (1978)

Asked participants to scan between two places on a map. Kosslyn determined the relationship between reaction time and distance. It took longer to scan between greater distances on the image, a result that supports the idea that visual imagery is spatial in nature. -- Island with seven locations, 21 trips -- Visual imagery is spatial.

Deborah Chalmers and Daniel Reisberg (1985)

Asked their participants to create mental images of ambiguous figures. Participants who were holding a mental image of the duck/rabbit figure were unable to flip from one perception to another

Depictive representation

Corresponds to spatial representation. So-called because a spatial representation can be depicted by a picture. Similar to realistic pictures - How the visual appearance of the boat can be represented propositionally. Paths between motor and porthole and motor and anchor indicate the number of nodes that would be traversed between these parts of the boat.

Samuel Le Bihan and coworkers (1993)

Demonstrated that both perception and imagery activate the visual cortex. Activity in the striate cortex increased both when a person observed presentations of actual visual stimuli (marked "Perception") and when the person was imagining the stimulus ("Imagery"). In contrast, activity is low when there is no actual or imagined stimulus. - Overlap in brain activation - Visual cortex

Maria Kozhevnikov and coworkers (2005)

Did an experiment in which they first presented a questionnaire designed to determine participants' preference for using imagery versus verbal-logical strategies when solving problems. Kozhevnikov classified the participants as visualizers or verbalizers. There were differences between participants with a low score on the PFT (low spatial imagery) and participants with a high score (high spatial imagery). 62% of the low spatial imagers had high scores on the VVIQ, meaning they had high object imagery, whereas 51% of the high spatial imagers had low scores on the VVIQ, meaning they had low object imagery.

Topographic map

Each point on a visual stimulus causes activity at a specific location on a brain structure, such as the visual cortex, and points next to each other on the stimulus cause activity at points next to each other on the structure

Mental imagery

Experiencing a sensory impression in the absence of sensory input

Dissociations Between Imagery and Perception

Guariglia and coworkers (1993) - Brain-damaged patient - Patient's perceptions intact, but mental images were impaired R.M. - 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) C.K. - Inability to name pictures of objects, even his own drawings, in front of him - Could draw objects in great detail from memory (using imagery)

Martha Farah and coworkers (1993)

Had M.G.S. perform the mental walk task in which she imagined walking toward an animal and estimated how close she was when the image began to overflow her visual field. But when she had her repeat this task after her right occipital lobe had been removed, the distance increased to 35 feet. This occurred because 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

Shepard and Metzlerr (1971)

Had participants indicate whether two pictures were of the same object or of different objects. The time it took to decide that two views were of the same object was directly related to how different the angles were between the two views. Participants were mentally rotating one of the views to see whether it matched the other one - Mental chronometry

Stephen Kosslyn and coworkers (1999)

Presented transcranial magnetic stimulation to the visual cortex while participants were carrying out either a perception task or an imagery task. For the perception task, participants briefly viewed a display and were asked to make a judgment about the stripes in two of the quadrants. The imagery task was the same, but the participants closed their eyes and based their judgments on their mental image of the display - Response time slower for both - Brain activity in visual area of brain plays a causal role for both perception and imagery

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 - Images are spatial, like perception

Edoardo Bisiach and Claudio Luzzatti (1978)

Tested the imagery of a patient with unilateral neglect by asking him to describe things he saw when imagining himself standing at one end of the Piazza del Duomo in Milan, a place with which he had been familiar before his brain was damaged. The patient's responses showed that he neglected the left side of his mental image, just as he neglected the left side of his perceptions. Thus, when he imagined himself standing at A, he neglected the left side and named only objects to his right.

Object imagery

The ability to image visual details, features, or objects.

Imagery debate

The debate about whether imagery is based on spatial mechanisms, such as those involved in perception, or on propositional mechanisms that are related to language - Depictive representation

Imageless thought debate

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

Giorgio Ganis and coworkers (2004)

Used fMRI to measure activation under two conditions, perception and imagery. For the perception condition, participants observed a drawing of an object, such as a tree. For the imagery condition, participants were told to imagine a picture that they had studied before, when they heard a tone. Perception and imagery both activate the same areas in the frontal lobe. However, perception activates much more of the visual cortex in the occipital lobe at the back of the brain - Complete overlap of activation by perception and imagery in front of the brain - Differences near back of the brain

Matthew Johnson and Marcia Johnson (2014)

Used multivoxel pattern analysis (MVPA) to study the relation between imagery and perception by training a classifier by presenting four different kinds of scenes—beach, desert, field, or house—to a person in a scanner. The classifier predicted the correct picture on 63 percent of the trials, which is above chance accuracy. When participants imagined one of the scenes, there was 55 percent accuracy—not as good as predicting what the person was perceiving, but still above chance.

Gabriel Kreiman and coworkers (2000)

Were able to study patients who had electrodes implanted in various areas in their medial temporal lobe, which includes the hippocampus and the amygdala. They found neurons that responded to some objects (baseball) but not to others (face). Neuron fired in the same way when the person closed his or her eyes and imagined a baseball (good firing) or a face (no firing) - Imagery neuron

Is Imagery Spatial or Propositional?

Zenon Pylyshyn (1973) Stated that the spatial experience of mental images, = is an epiphenomenon. Proposed that imagery is propositional. - Can be represented by abstract symbols - Imagery debate