PSY 380 Exam 3

Psychologists that believed that thoughts cannot occur without imagery agreed with Aristotles idea that

"thought is impossible without an image"

John Watson described images as

"unproved" and "mythological" and therefore not worthy of study.

Stephen Kosslyn has done enough research to fill how many books

3

Results for Kosslyn's new mental scanning experiment involving the island

Just as in the boat experiment, it took longer to scan between greater distances on the image, a result that supports the idea that visual imagery is spatial in nature.

How can we use studies of people with brain damage to help us understand imagery?

One approach is to determine how brain damage affects imagery. Another approach is to determine how brain damage affects both imagery and perception, and to note whether both are affected in the same way.

Orchestra conductors' using a technique called "inner audition" to practice without their orchestras by imagining a musical score in their minds is an example of

auditory imagery

Samuel Le Bihan and coworkers demonstrated that

both perception and imagery activate the visual cortex. Figure 10.13 shows how 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").

Paivio proposed the conceptual peg hypothesis. this hypothesis suggest that

concrete nouns create images that other words can "hang onto."

John Anderson warned what

despite this evidence, we still can't rule out the propositional explanation.

mental chronometry

determining the amount of time needed to carry out a cognitive task

Kreiman and coworkers were able to study patients who had

electrodes implanted in various areas in their medial temporal lobe, which includes the hippocampus and the amygdala, in order to determine the source of severe epileptic seizures that could not be controlled by medication..

Pylyshyn argued that the spatial experience of mental images is an

epiphenomenon

Pylyshyn argues that just as the spatial experience of mental images is an ______________, brain activity can also be an _______________. According to Pylyshyn, brain activity in response to imagery may indicate that something is happening but may have nothing to do with causing imagery.

epiphenomenon; epiphenomenon.

Results of Kreiman and coworkers experiment

found neurons that responded to some objects but not to others. For example, the records in Figure 10.12a show the response of a neuron that responded to a picture of a baseball but did not respond to a picture of a face. Notice in Figure 10.12b that this 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). Kreiman calls these neurons imagery neurons

propositional representation

is one in which relationships can be represented by abstract symbols, such as an equation, or a statement such as "The cat is under the table."

Roger Shepard and Jacqueline Metzler inferred cognitive processes by using what

mental chronometry

One technique Paivio used was called what

paired-associate learning

Evidence supporting the idea that imagery was not required for thinking was Francis Galton's observation that

people who had great difficulty forming visual images were still quite capable of thinking.

Pylyshyn proposed that the mechanism underlying imagery is not spatial but

propositional

studies in which activity is recorded from single neurons in humans are

rare

epiphenomenon

something that accompanies the real mechanism but is not actually part of the mechanism

People have the ability to imagine

tastes, smells, and tactile experiences.

to counter the tacit knowledge explanation of Kosslyn's mental scanning results, Ronald Finke and Stephen Pinker created an experiment

they briefly presented a four-dot display and then after a 4 second delay, presented an arrow. The subjects tasks was to indicate whether the arrow was pointing to any of the dots they had just seen.

Albert Einstein's description of how he developed the theory of relativity by imagining himself traveling beside a beam of light is another example of what

visual imagery

spatial representation

—a representation in which different parts of an image can be described as corresponding to specific locations in space.

What is one of the most famous accounts of how visual imagery led to a scientific discovery

Friedrich August Kekule said that the structure of benzene came to him in a dream in which he saw a writhing chain that formed a circle that resembled a snake, with its head swallowing its tail. this visual image gave Kekule the insight that the carbon atoms that make up the benzene molecule are arranged in a ring.

Kosslyns experiment to answer his question whether this relationship between viewing distance and the ability to perceive details also occurs for mental images.

Kosslyn (1978) asked subjects to imagine two animals, such as an elephant and a rabbit, next to each other and to imagine that they were standing close enough to the larger animal that it filled most of their visual field ( Figure 10.9a ). He then posed questions such as "Does the rabbit have whiskers?" and asked his subjects to find that part of the animal in their mental image and to answer as quickly as possible. When he repeated this procedure but told subjects to imagine a rabbit and a fly next to each other, subjects created larger images of the rabbit, as shown in Figure 10.9b . The result of these experiments, shown alongside the pictures, was that subjects answered questions about the rabbit more rapidly when it filled more of the visual field. .

Kosslyn and co workers experiment that dealt with the possibility that brain activity in response to imagery may indicate that something is happening but may have nothing to do with causing imagery.

Kosslyn and coworkers (1999) presented transcranial magnetic stimulation to the visual cortex while subjects were carrying out either a perception task or an imagery task. For the perception task, subjects briefly viewed a display like the one in Figure 10.17 and were asked to make a judgment about the stripes in two of the quadrants. For example, they might be asked to indicate whether the stripes in quadrant 3 were longer than the stripes in quadrant 2. The imagery task was the same, but instead of actually looking at the stripes while answering the questions, the subjects closed their eyes and based their judgments on their mental image of the display. Kosslyn measured subjects' reaction time to make the judgment, both when transcranial magnetic stimulation was being applied to the visual area of the brain and also during a control condition when the stimulation was directed to another part of the brain.

The classic demonstration of interaction between perception and imagery dates back to 1910, when Cheves Perky did an experiment

Perky asked her subjects to "project" visual images of common objects onto a screen, and then to describe these images. Unbeknownst to the subjects, Perky was back-projecting a very dim image of this object onto the screen. Thus, when subjects were asked to create an image of a banana, Perky projected a dim image of a banana onto the screen. Interestingly, the subjects' descriptions of their images matched the images that Perky was projecting. For example, they described the banana as being oriented vertically, just as was the projected image. Even more interesting, not one of Perky's 24 subjects noticed that there was an actual picture on the screen. They had apparently mistaken an actual picture for a mental image.

results of Kosslyn and co workers experiment that dealt with the possibility that brain activity in response to imagery may indicate that something is happening but may have nothing to do with causing imagery.

The results indicated that stimulation caused subjects to respond more slowly, and that this slowing effect occurred both for perception and for imagery. Based on these results, Kosslyn 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 role in both perception and imagery.

In addition to asking subjects to respond to details in visual images, Kosslyn also asked them to do what

a mental walk task , in which they were to imagine that they were walking toward their mental image of an animal. Their task was 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. The result was that subjects had to move closer for small animals (less than a foot away for a mouse) than for larger animals (about 11 feet away for an elephant), just as they would have to do if they were walking toward actual animals. This result provides further evidence for the idea that images are spatial, just like perception.

Why is Kreiman's discovery of imagery neurons important?

both because it demonstrates a possible physiological mechanism for imagery and because these neurons respond in the same way to perceiving an object and to imagining it, thereby supporting the idea of a close relation between perception and imagery.

Paivio showed that it was easier to remember what

concrete nouns, like truck or tree, that can be imaged, than it is to remember abstract nouns, like truth or justice, that are difficult to image.

Glen Lea proposed an alternative explanation to Kosslyn's results of his mental scanning experiment

he proposed that as subjects scanned, they may have encountered other interesting parts, such as the cabin, and this distraction may have increased their reaction time.

Zenon Pylyshyn proposed another explanation for Kosslyn's new experiment involving the island. This started the

imagery debate

Martha Farah experiment

instructed her subjects to imagine either the letter H or the letter T on a screen ( Figure 10.11a). Once they had formed a clear image on the screen, they pressed a button that caused two squares to flash, one after the other ( Figure 10.11b). One of the squares contained a target letter, which was either an H or a T . The subjects' task was to indicate whether the letter was in the first square or the second one. The results, shown in Figure 10.11c, indicate that the target letter was detected more accurately when the subject had been imagining the same letter rather than the different letter. Farah interpreted this result as showing that perception and imagery share mechanisms; later experiments that have also shown that imagery can affect perception have come to the same conclusion.

what is an example of an epiphenomenon

is lights flashing as a mainframe computer carries out its calculations. The lights may indicate that something is going on inside the computer, but they don't necessarily tell us what is actually happening. In fact, if all of the lightbulbs blew out, the computer would continue operating just as before.

results for Kosslyn's mental scanning experiment of the boat and anchor

it took longer for subjects to find parts that are located farther from the initial point of focus because they would be scanning across the image of the object.

What was important about the Shepard and Metzler's experiment

it was one of the first to apply quantitative methods to the study of imagery and to suggest that imagery and perception may share the same mechanisms.

pylyshyn said that

just because we experience imagery as spatial, that doesn't mean that the underlying representation is spatial.

Results of Finke and Pinker's experiment that was trying to counter the tacit knowledge explanation

outward from the arrow, they took longer to respond for greater distances between the arrow and the dot. In fact, the results look very similar to the results of other scanning experiments. Finke and Pinker argue that because their subjects wouldn't have had time to memorize the distances between the arrow and the dot before making their judgments, it is unlikely that they used tacit knowledge about how long it should take to get from one point to another.

In a paired-associate learning experiment, subjects are presented with _________________. They are then presented during the test period, with the first word from each pair. Their task is to recall the word that was paired with it during the study period.

pairs of words, like boat-hat or car-house, during a study period.

depictive representations

representations that are like realistic pictures of an object, so that parts of the representation correspond to parts of the object

To answer Glen Lea's concern, Kosslyn had subjects

scan between two places on a map. He had them imagine an island with seven different locations. By having subjects scan between every possible pair of locations (a total of 21 trips), Kosslyn determined the relationship between reaction time and distance.

visual imagery

seeing in the absence of a visual stimulus

Wundt proposed that images were one of the three basic elements of consciousness along with

sensations and feelings

Amir Amedi and coworkers experiment

showed overlap, but also found that when subjects were using visual imagery, some areas associated with nonvisual stimuli, such as hearing and touch, were deactivated . That is, during imagery, their activation was decreased. Amedi suggests that the reason for this might be that visual images are more fragile than real perception and this deactivation helps quiet down irrelevant activity that might interfere with the mental image.

Shepard and Metzler's results showed that mental and perceptual images both involve

spatial representation of the stimulus. That is, the spatial experience for both imagery and perception matches the layout of the actual stimulus.

The topographic map refers to the fact that

specific locations on a visual stimulus cause activity at specific locations in the visual cortex and that points next to each other on the stimulus cause activity at locations next to each other on the cortex.

tacit knowledge explanation

states that subjects unconsciously use knowledge about the world in making their judgments

In addition to suggesting that Kosslyn's results can be explained in terms of propositional representations, Pylyshyn also suggested that 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.

Mental scanning

subjects create mental images and then scan them in their minds

Kosslyn wondered what would happen if subjects created mental images of different sizes? what did he do to answer this question?

subjects were instructed to create small, medium, and large visual images while they were in a brain scanner. The result, indicated by the symbols in Figure 10.14b , is that when subjects created small visual images, activity was centered near the back of the brain (circles), but as the size of the mental image increased, activation moved toward the front of the visual cortex (squares and triangles), just as it does for perception. (Notice that one of the triangles representing large images is near the back of the visual cortex. Kosslyn suggests that this could have been caused by activation by internal details of the larger image.) Thus, both imagery and perception result in topographically organized brain activation.

The weight of the evidence supports the idea

that imagery is served by a spatial mechanism and that it shares mechanisms with perception.

Martha Farah pointed out what

that it is difficult to rule out Pylyshyn's tacit knowledge explanation just on the basis of the results of behavioral experiments like the ones we have been describing. She argued that it is always possible that subjects can be influenced by their past experiences with perception, so they could unknowingly be simulating perceptual responses in imagery experiments. For example, in the mental walk experiments, in which subjects were supposed to be imagining that they were walking toward their mental image of an animal, subjects could be using their knowledge from prior experience in perceiving animals to conclude that they would have to be closer to a mouse than to an elephant before these animals would fill up their field of view.

Mental imagery

the ability to recreate the sensory world in the absence of physical stimuli.

research on the topographic map on the visual cortex indicates that looking at a small object causes activity in

the back of the visual cortex

The idea of a link between imagery and thinking gave rise to what debate

the imageless thought debate

Shepard and Metzler's experiment

their subjects task was to indicate as rapidly as possible, whether the two pictures were of the same object or of different objects. This experiment showed that the time it took to decide that two views of the same object was directly related to how different the angles were between the two views. This result was interpreted as showing that subjects were mentally rotating one of the views to see whether it matched the other one.

how do mental images differ from perception?

they are not as vivid or long lasting

In one of his early experiments, Kosslyn (1973) asked subjects to

to memorize a picture of an object 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. They were then asked to look for another part of the boat, such as the motor, and to press the "true" button when they found this part or the "false" button when they couldn't find it.

research on the topographic map on the visual cortex indicates that looking at a larger object causes activity

to spread toward the front of the visual cortex

Kosslyn created an experiment that made use of the way the visual cortex is organized as a

topographic map

The behaviorists branded the study of imagery as what

unproductive because visual images are invisible to everyone except the person experiencing them.

Giorgio Ganis and coworkers experiment

used fMRI to measure activation under two conditions, perception and imagery. For the perception condition, subjects observed a drawing of an object, such as the tree in Figure 10.15 . For the imagery condition, subjects were told to imagine a picture that they had studied before, when they heard a tone. For both the perception and imagery tasks, subjects had to answer a question such as "Is the object wider than it is tall?"

Raphael's ability to "see" Susan's book laying on the desk, even though it is not present, is an example of

visual imagery

The author's experience of being able to visually remember seeing the Pacific Ocean after cresting a mountain in California is an example of what

visual imagery

Sue-Hynn Lee and coworkers experiment

were able to use brain activation patterns to determine what their subjects were perceiving or imagining (see Method: Neural Mind Reading, Chapter 5 , page 145 ). They found that activity in the visual cortex in the occipital lobe resulted in the best prediction for what their subjects were perceiving, and activity in higher visual areas was the best predictor of what their subjects were imagining. This makes sense when we remember that the visual cortex responds to small details, such as oriented lines, that would be more obvious when perceiving, and higher visual areas respond more to whole objects.

Results of Ganis's experiment

which shows activation at three different locations in the brain. Figure 10.16a shows that perception and imagery both activate the same areas in the frontal lobe. Figure 10.16b shows the same result further back in the brain. However, Figure 10.16c , which shows activation in the visual cortex, in the occipital lobe at the back of the brain, indicates that perception activates much more of this area of the brain than does imagery. This greater activity for perception isn't surprising because the visual cortex is where signals from the retina first reach the cortex. Thus, there is almost complete overlap of the activation caused by perception and imagery in the front of the brain, but some difference near the back of the brain.

imagery debate

—a debate about whether imagery is based on spatial mechanisms, such as those involved in perception, or on mechanisms related to language, called propositional mechanisms.