Ch. 10

Question 1

Learning Objectives

Answer 1

10-1
Explain how a “picture in your head” created by imagining an object compares to the experience you have when you see the actual object.
10-2
Describe how damage to the brain can affect the ability to form visual images.
10-3
Identify how we can use visual imagery to improve memory.
10-4
Explain how people differ in their ability to create visual images.
10-5
Describe how aphantasia differs from typical mental imagery.
10-6
Apply mental imagery in practical settings.

Question 2

visual imagery

Answer 2

A type of mental imagery involving vision, in which an image is experienced in the absence of a visual stimulus.

Question 3

Mental imagery

Answer 3

Experiencing a sensory impression in the absence of sensory input.

Mental imagery is part of an umbrella cognitive function called imagination.

However, mental imagery does not have to be visual. People have the ability to imagine tastes, smells, and tactile experiences

One message of these examples is that imagery provides a way of thinking that adds another dimension to the verbal techniques usually associated with thinking. Imagery is associated with most people’s everyday experience.

Question 4

Imagination

Answer 4

The ability of the mind to be creative and resourceful, actively generating sensory experiences, ideas, or concepts of external stimuli without their physical presence.

Notice both “imagery” and “imagination” have the root “imag-,” which implies a strong visual component to this phenomenon.

Question 5

imageless thought debate

Answer 5

We can trace the history of imagery back to the first laboratory of psychology, founded by Wilhelm Wundt.

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

Wundt proposed that images were one of the three basic elements of consciousness, along with sensations and feelings. He also proposed that because images accompany thought, studying images was a way of studying thinking. This idea of a link between imagery and thinking gave rise to the imageless thought debate , with some psychologists taking up Aristotle’s idea that “thought is impossible without an image” and others contending that thinking can occur without images.

Evidence supporting the idea that imagery was not required for thinking was Francis Galton’s (1883) observation that people who had great difficulty forming visual images were still quite capable of thinking

Other arguments both for and against the idea that images are necessary for thinking were proposed in the late 1800s and early 1900s, but these arguments and counterarguments ended when behaviorism toppled imagery from its central place in psychology (Watson, 1913; see Chapter 1).

The behaviorists branded the study of imagery as unproductive because visual images are invisible to everyone except the person experiencing them. The founder of behaviorism, John Watson, described images as “unproven” and “mythological” (1928) and therefore not worthy of study.

The dominance of behaviorism from the 1920s through the 1950s pushed the study of imagery out of mainstream psychology. However, this situation changed when the study of cognition was reborn in the 1950s.

Question 6

Propositional

Answer 6

Information processed in the mind using language and symbols.

Question 7

Spatial

Answer 7

Information processed in the mind visually in relation to particular location.

Question 8

depictive

Answer 8

Information processed in the mind visually in relation to object qualities and recognition.

Question 9

Visual information processed in the mind is said to be

Answer 9

Spatial and depictive

this corresponds to the two paths of visual processing: the dorsal “where” pathway and the ventral “what” pathway, respectively.

As we will discuss, some research supports the idea that information is mentally represented propositionally whereas other studies support the idea that information is represented depictively and spatially in the mind.

Question 10

Joel Pearson and Stephen Kosslyn (2015)

Answer 10

set out with the goal of “ending the imagery debate.” Their assessment of the research through these many decades concluded that humans depend on a combination of propositional and depictive representations, and that, moving forward, the imagery debate should focus on understanding the many forms of human mental representation.

Question 11

conceptual peg hypothesis

Answer 11

A hypothesis, associated with 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.

One example of a method that linked behavior and cognition is Alan Paivio’s (1963) work on memory. Paivio demonstrated it was easier to remember 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. One technique Paivio used was paired-associate learning.

In a paired-associate learning experiment, participants are presented with pairs of words, like boat–hat or car–house, during a study period. 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. Thus, if they were presented with the word boat, the correct response would be hat.

Question 12

mental chronometry

Answer 12

determining the amount of time needed to carry out various cognitive tasks.

Whereas Paivio inferred cognitive processes by measuring memory, Roger Shepard and Jacqueline Metzler (1971) inferred cognitive processes by using mental chronometry.

In Shepard and Metzler’s experiment, which we described in Chapter 5, participants saw pictures like the ones in Figure 10.1. Their task was to indicate, as rapidly as possible, whether the two pictures were of the same object or different objects. This experiment showed that 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 (review Figure 5.14). This result was interpreted as showing that participants were mentally rotating one of the views to determine whether it matched the other one.

What was important about this experiment was that 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. (References to “mechanisms” include both mental mechanisms, such as ways of manipulating perceptual and mental images in the mind, and brain mechanisms, such as which structures are involved in creating perceptual and mental images.)

Question 13

Mental scanning

Answer 13

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

The idea that imagery and perception may share the same mechanisms is based on the observation that although mental images differ from perception in that they are not as vivid or long lasting, imagery shares many properties with perception. 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.

This idea, that there is a spatial correspondence between imagery and perception, is supported by many experiments by Stephen Kosslyn involving a task called mental scanning , in which participants create mental images and then scan them in their minds.

Question 14

Kosslyn’s Mental Scanning Experiments

Answer 14

In one of his early experiments, Kosslyn (1973) asked participants to memorize a picture of an object, such as the boat in Figure 10.2, 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.

Using the image in their mind, 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 could not find it.

Kosslyn reasoned that if imagery, like perception, is spatial, then it should take 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. This result is actually what happened, and Kosslyn took it as evidence for the spatial nature of imagery.

Question 15

Glen Lea (1975)

Answer 15

However, as often happens in science, another researcher proposed a different explanation. Glen Lea (1975) proposed that as participants scanned, they may have encountered other interesting parts, such as the cabin, and this distraction may have increased their reaction time.

To answer this concern, Kosslyn and colleagues (1978) did another scanning experiment, this time asking participants to scan between two places on a map.

Kosslyn’s participants used the same procedure you just completed for the demonstration but were told to imagine an island, like the one in Figure 10.4a, that contained seven different locations. By having participants scan between every possible pair of locations (a total of 21 trips), Kosslyn determined the relationship between reaction time and distance shown in Figure 10.4b. 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.

As convincing as Kosslyn’s results were, however, Zenon Pylyshyn (1973) proposed another explanation, which started the 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.

Question 16

spatial representations

Answer 16

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

Kosslyn and colleagues interpreted results from their experiment on imagery as supporting the idea that the mechanism responsible for imagery involves spatial representations.

a spatial representation would involve a spatial layout showing the cellphone, the laptop, and the desk that could be represented in a picture (Figure 10.5).

Spatial representations such as the picture of the cellphone on the desk near the laptop, in which parts of the representation correspond to parts of the object, are called depictive representations .

Question 17

epiphenomenon

Answer 17

However, Pylyshyn (1973) disagreed, saying that just because we experience imagery as spatial, that does not mean that the underlying representation is spatial. After all, one thing that is clear from research in cognitive psychology is that we are not always aware of what is going on in our minds. The spatial experience of mental images, argues Pylyshyn, is an epiphenomenon —something that accompanies the real mechanism but is not actually part of the mechanism.

Question 18

propositional representations

Answer 18

A representation in which relationships are represented by symbols, as when the words of a language represent objects and the relationships between objects.

Pylyshyn proposed that, rather than the spatial representations suggested by Kosslyn, the mechanism underlying imagery involves propositional representations, where relationships between objects are represented by symbols, such as an equation, or a statement, such as “The cellphone is on the desk by the laptop.”

In contrast, a spatial representation would involve a spatial layout showing the cellphone, the laptop, and the desk that could be represented in a picture (Figure 10.5).

Spatial representations such as the picture of the cellphone on the desk near the laptop, in which parts of the representation correspond to parts of the object, are called depictive representations .

Question 19

We can understand the propositional approach better by returning to the depictive representation of Kosslyn’s boat

Answer 19

Figure 10.6 shows how the visual appearance of this boat can be represented propositionally. The words indicate parts of the boat, the length of the lines indicate the distances between the parts, and the words in parentheses indicate the spatial relations between the parts. A representation such as this one would predict that when starting at the motor, it should take longer to scan and find the anchor than to find the porthole because it is necessary to travel across three links to get to the porthole (dashed line) and four links to get to the anchor (dotted line). This kind of explanation proposes that imagery operates in a way similar to the semantic networks.

after many years of discussion and experimentation, the weight of the evidence supports the idea that imagery is served by a spatial mechanism and that it shares mechanisms with perception.

Question 20

Comparing Imagery and Perception

Size in the Visual Field

Answer 20

another experiment by Kosslyn. This one considers how imagery is affected by the size of an object in a person’s visual field.

If you observe an automobile from far away, it fills only a portion of your visual field, and it is difficult to see small details such as the door handle. As you move closer, it fills more of your visual field, and you can perceive details like the door handle more easily (Figure 10.7). With these observations about perception in mind, Kosslyn wondered whether this relationship between viewing distance and the ability to perceive details also occurs for mental images.

To answer this question, 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 (Figure 10.8a). He then posed questions such as “Does the rabbit have whiskers?” and asked his participants 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 participants to imagine a rabbit and a fly next to each other, participants created larger images of the rabbit, as shown in Figure 10.8b. The result of these experiments, shown alongside the pictures, was that participants answered questions about the rabbit more rapidly when it filled more of the visual field.

Question 21

mental walk task

Answer 21

In addition to asking participants to respond to details in visual images, Kosslyn also asked them to do 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 participants 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.

Question 22

Comparing Imagery and Perception

Interactions of Imagery and Perception

Answer 22

Another way to demonstrate connections between imagery and perception is to show that they interact with one another.

The basic rationale behind this approach is that if imagery affects perception, or perception affects imagery, this means that imagery and perception both have access to the same mechanisms.

The classic demonstration of interaction between perception and imagery dates back to 1910, when Cheves Perky did the experiment pictured in Figure 10.9. Perky asked her participants to “project” visual images of common objects onto a screen and then to describe these images. Unbeknownst to the participants, Perky was back-projecting a very dim image of this object onto the screen. Thus, when participants were asked to create an image of a banana, Perky projected a dim image of a banana onto the screen. Interestingly, the participants’ 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 participants noticed that there was an actual picture on the screen. They had apparently mistaken an actual picture for a mental image.

Question 23

Comparing Imagery and Perception

Interactions of Imagery and Perception

Answer 23

Modern researchers have replicated Perky’s result (see Craver-Lemley & Reeves, 1992; Segal & Fusella, 1970) and have demonstrated interactions between perception and imagery in several other ways. Martha Farah (1985) instructed her participants to imagine either the letter H or the letter T on a screen. Once they had formed a clear image on the screen, they pressed a button that caused two squares to flash, one after the other. 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. Farah found that the target letter was detected more accurately when participants imagined the same letter rather than a 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 (Kosslyn & Thompson, 2000; Pearson et al., 2008).

Question 24

imagery neurons

Answer 24

Neurons that fire rapidly during perception and imagery.

Gabriel Kreiman and colleagues (2000) were able to study patients who had electrodes implanted in various regions in their medial temporal lobe, which includes the hippocampus and the amygdala. Kreiman found neurons that fired rapidly to some objects but not to others.

For example, the records in Figure 10.10a show the response of a neuron that fired rapidly to a picture of a baseball but did not respond to a picture of a face.

In addition, Figure 10.10b shows that this neuron fired rapidly in the same way when the person closed their eyes and imagined a baseball (rapid firing) or a face (base level firing). Kreiman called these neurons imagery neurons .

Kreiman’s discovery of imagery neurons is 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.

However, instead of recording from single neurons, most research on humans has involved brain imaging that measures brain activity as participants are perceiving objects and creating visual images of these objects

Question 25

Samuel Le Bihan and colleagues (1993)

Answer 25

An early study of imagery using brain imaging was carried out by Samuel Le Bihan and colleagues (1993), who demonstrated that both perception and imagery activate the visual cortex. Figure 10.11 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”). In another brain imaging experiment, asking participants to think about questions that involved imagery—for example, “Is the green of the trees darker than the green of the grass?”—generated a greater response in the visual cortex than asking non-imagery questions, such as “Is the intensity of electrical current measured in amperes?”. Results of Le Bihan et al.’s (1993) study measuring brain activity using functional magnetic resonance imaging (fMRI). Activity increases to presentation of a visual stimulus (shaded area marked “Stimulus on”) and also increases when participants are imagining the stimulus (area marked “Imagined stimulus”). In contrast, activity is low when there is no actual or imagined stimulus.

Question 26

topographic map

Answer 26

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. Another imaging experiment, by Stephen Kosslyn and colleagues (1995), made use of the way the visual cortex is organized as a topographic map , a phenomenon in which specific locations on a visual stimulus cause activity at specific locations in the visual cortex. Points next to each other on the stimulus cause activity at locations next to each other on the cortex. Research on the topographic map of the visual cortex indicates that looking at a small object that takes up only a small part of the center of the visual field causes activity in the back center of the visual cortex, as shown by the green area in Figure 10.12a. However, looking at larger objects that take up substantially more of the visual field causes the activity to spread outward “topographically” in the visual cortex, as indicated by the red area.

Question 27

What would happen, Kosslyn wondered, if participants created mental images of different sizes?

Answer 27

To answer this question, participants 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 10.12b, is that when participants 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 the activation of internal details of the larger image.) Thus, both imagery and perception result in topographically organized brain activation.

Question 28

Giorgio Ganis and colleagues (2004)

Answer 28

Another approach to studying imagery and the brain has been to determine whether there is overlap between brain regions activated by perceiving an object and those activated by creating a mental image of the object. These experiments have demonstrated an overlap between regions activated by perception and by imagery—but have also found differences. For example, Giorgio Ganis and colleagues (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 the tree in Figure 10.13. For the imagery condition, participants were told to imagine a picture that they had studied before, when they heard a tone. For both the perception and imagery tasks, participants had to answer a question such as “Is the object wider than it is tall?” Results of Ganis’s experiment are shown in Figure 10.14, which indicates activation at three different locations in the brain. Figure 10.14a shows that perception and imagery both activate the same regions in the frontal lobe. Figure 10.14b shows the same result farther back in the brain. However, Figure 10.14c, 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 region of the brain than does imagery. This greater activity for perception makes sense 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.

Question 29

Amir Amedi and colleagues (2005)

Answer 29

Other experiments have also concluded that there are similarities but also some differences between brain activation for perception and imagery. For example, an fMRI experiment by Amir Amedi and colleagues (2005) showed overlap but also found that when participants were using visual imagery, the response of some regions associated with non-visual stimuli, such as hearing and touch, was decreased. Amedi suggests that the reason for this decrease might be that visual images are more fragile than real perception, and this reduction in the activity of brain regions related to hearing and touch helps quiet down irrelevant activity that might interfere with the mental image.

Question 30

Multivoxel Pattern Analysis

Answer 30

Another way brain imaging has been applied to studying possible links between imagery and perception is multivoxel pattern analysis (MVPA). the procedure in MVPA is to train a classifier to associate a pattern of voxel activation with particular stimuli, like the apple and pear in Figure 7.15, and then to present a stimulus and determine if the classifier can identify it, based on the pattern of voxel activity created by the stimulus.

Question 31

Matthew Johnson and Marcia Johnson (2014)

Answer 31

used MVPA procedure to study the relation between imagery and perception by training a classifier. They presented four different kinds of scenes—beach, desert, field, or house—to a participant in a scanner (Figure 10.15a). After the classifier was trained on these perceptual stimuli, it was time for the test. Voxel activity was recorded as a participant viewed a picture (for example, the beach scene), and the classifier predicted, from two possibilities (say, the beach scene or the house), which picture the person was perceiving (Figure 10.15b). The result was that the classifier predicted the correct picture on 63 percent of the trials, which is above chance accuracy (where chance performance is 50 percent). This “train on perception, test on perception” experimental design demonstrated that the classifier could use the information it had learned during perception training to predict what the participant was seeing. However, what if the perception-trained classifier was asked to indicate which of two scenes the participant was imagining? The result of experiments in which voxel activity was measured as participants imagined one of the scenes was 55 percent accuracy—not as good as predicting what the person was perceiving, but still above chance. Clearly, a lot of work remains to be done before classifiers can accurately predict what a person is perceiving or imagining, but identifying with above-chance accuracy what a person is imagining based on activity collected when the person was perceiving is impressive, and other researchers have reported similar results. Promising research has found that classifiers are able to use activity in area V4 of the visual cortex to predict behavioral performance related to imagery of specific colors. Others have noted classifiers find remarkable similarity in neural frequency between visual imagery and visual perception, in particular regarding a frequency described as the “alpha frequency band” in the parietal and occipital lobes. Alpha frequencies are those recorded in EEG during wakefulness or calmness. The similarity in alpha frequencies for perception and imagery highlights the interconnected nature of these neural mechanisms.

Question 32

Transcranial Magnetic Stimulation (TMS)

Answer 32

Another technique used to investigate connections between perception and imagery involves transcranial magnetic stimulation (TMS). Stephen Kosslyn and colleagues (1999) presented TMS 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 like the one in Figure 10.16 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 participants closed their eyes and based their judgments on their mental image of the display. Kosslyn measured participants’ reaction time to make the judgment, both when TMS was being applied to the visual region of the brain and also during a control condition when the stimulation was directed to another part of the brain. The results indicated that stimulation caused participants to respond more slowly, and that this slowing effect occurred both for perception and for imagery. Based on these results, Kosslyn concluded that brain activity in the visual cortex plays a causal role in both perception and imagery.

Question 33

Neuropsychological Case Studies

Answer 33

How can we use studies of people whose brains have been damaged by traumatic injury to help us understand imagery? One approach is to determine how damage to the brain affects imagery. Another approach is to determine how injury to the brain affects both imagery and perception, and to note whether both are affected in the same way.

Question 34

Neuropsychological Case Studies Removing Part of the Visual Cortex Decreases Image Size

Answer 34

Patient M.G.S. was a young woman who was about to have part of her right occipital lobe removed as a treatment for a severe case of epilepsy. Before the operation, Martha Farah and colleagues (1993) had M.G.S. perform the mental walk task that we described earlier, in which she imagined walking toward an animal and estimated how close she was when the image began to overflow her visual field. Figure 10.17 shows that before the operation, M.G.S. felt she was about 15 feet from an imaginary horse before its image overflowed. But when Farah had her repeat this task after her right occipital lobe had been removed, the distance increased to 35 feet. This change 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.

Question 35

Neuropsychological Case Studies Problems with Perceiving Are Accompanied by Problems with Imagery

Answer 35

Many cases have been studied in which a patient whose brain has been damaged by traumatic injury has a perceptual problem and also has a similar problem in creating images. For example, people who have lost the ability to see color due to damage to the brain are also unable to create colors through imagery. Damage to the parietal lobes can cause a condition called unilateral neglect , in which the patient ignores objects in one half of the visual field, even to the extent of shaving just one side of the face or eating only the food on one side of the plate. 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 (small a’s). When he imagined himself standing at B, he continued to neglect the left side, again naming only objects on his right (small b’s). The correspondence between the physiology of mental imagery and the physiology of perception, as demonstrated by brain scans in participants with healthy brain function in contrast to those of participants whose brains have been damaged by traumatic injury resulting in unilateral neglect, supports the idea that mental imagery and perception share physiological mechanisms. However, not all physiological results support a one-to-one correspondence between imagery and perception.

Question 36

Neuropsychological Case Studies Dissociations Between Imagery and Perception

Answer 36

In Chapter 2, we described dissociations between different types of perception. Cases have also been reported of dissociations between imagery and perception. For example, Cecilia Guariglia and colleagues (1993) studied a patient whose injury to the brain had little effect on his ability to perceive but caused neglect in his mental images (his mental images were limited to only one side, as in the case of the man imagining the piazza in Milan). Another case of typical perception but impaired imagery is the case of R.M., who had suffered damage to his occipital and parietal lobes (Farah et al., 1988). R.M. was able to recognize objects and draw accurate pictures of objects that were placed before him. However, he was unable to draw objects from memory, a task that requires imagery. He also had trouble answering questions that depended on imagery, such as verifying whether the sentence “A grapefruit is larger than an orange” is correct. Dissociations have also been reported with the opposite result, so that perception is impaired, but imagery is relatively normal. For example, Marlene Behrmann and colleagues (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. Thus, he labeled the pictures in Figure 10.19a as a “feather duster” (the dart), a “fencer’s mask” (the tennis racquet), and a “rose twig with thorns” (the asparagus). These results show that C.K. could recognize parts of objects but could not integrate them into a meaningful whole. However, despite his inability to name pictures of objects, C.K. was able to draw objects from memory, a task that depends on imagery (Figure 10.19b). Interestingly, when he was shown his own drawings after enough time had passed that he had forgotten the actual drawing experience, he was unable to identify the objects he had drawn. These neuropsychological dissociations, in which perception is typical but imagery is poor (Guariglia’s patient and R.M.), or perception is poor, but imagery is typical (C.K.), present a paradox. On one hand, evidence for a double dissociation between imagery and perception (Table 10.1) is usually interpreted to mean that the two functions are served by different mechanisms (see page 42). However, this conclusion contradicts the other evidence we have presented that shows that imagery and perception share mechanisms. This apparent paradox highlights the difficulty in interpreting neuropsychological results. For one thing, the damage in individual cases varies greatly between individuals and usually is not restricted to the borders between regions in anatomical diagrams. In addition, it is important to bear in mind that much of the research that presents evidence for an overlap between perception and imagery also acknowledges that the overlap is only partial.

Question 37

Conclusions from the Imagery Debate

Answer 37

The imagery debate provides an outstanding example of a situation in which a controversy motivated a large amount of research. Most psychologists, examining the behavioral and physiological evidence, have concluded that imagery and perception are closely related and share some (but not all) mechanisms. The idea of shared mechanisms follows from all the parallels and interactions between perception and imagery. The idea that not all mechanisms are shared follows from some of the fMRI results, which show that the overlap between brain activation is not complete; some of the neuropsychological results, which show dissociations between imagery and perception; and also from differences between the experience of imagery and perception. For example, perception occurs automatically when we look at something, but imagery needs to be generated with some effort. Also, perception is stable—it continues as long as you are observing a stimulus—but imagery is fragile—it can vanish without continued effort. Another example of a difference between imagery and perception is that it is harder to manipulate mental images than perceptually created images. T his idea was demonstrated by Deborah Chalmers and Daniel Reisberg (1985), who asked their participants to create mental images of ambiguous figures such as the one in Figure 10.20, which can be seen as a rabbit or a duck. Perceptually, most people have little trouble successfully “flipping” between these two perceptions. However, Chalmers and Reisberg found that participants who were holding a mental image of this figure were unable to flip from one perception to another. Other research has shown that people can manipulate simpler mental images. For example, Ronald Finke and colleagues (1989) showed that when participants followed instructions to imagine a capital letter D, and then rotate it 90 degrees to the left and place a capital letter J at the bottom, they reported seeing an umbrella. Also, Fred Mast and Kosslyn (2002) showed that people who were good at imagery were able to rotate mental images of ambiguous figures if they were provided with extra information such as drawings of parts of the images that are partially rotated. So, the experiments on manipulating images lead to the same conclusion as all the other experiments we have described: Imagery and perception have many features in common, but there are also differences between them.

Question 38

Individual Differences in Visual Imagery

Answer 38

People differ in how they perceive things and how well they can maintain their attention, remember things, and solve problems. So makes sense that there are differences between people in terms of imagery as well. The idea that people differ in imaging was suggested in the 19th century by Francis Galton, who noted that there are “different degrees of vividness with which different persons have the faculty of recalling familiar scenes under the form of mental pictures”. Modern researchers have confirmed Galton’s idea of differences in people’s imaging and have added important details to the story.

Question 39

Individual Differences in Visual Imagery Maria Kozhevnikov and colleagues (2005)

Answer 39

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. This questionnaire involved solving different kinds of problems and indicating the strategies used to solve these problems. Kozhevnikov classified the participants as visualizers or verbalizers, so this initial result indicated that some people use imagery to solve problems and some people do not. We will describe the results of Kozhevnikov’s experiments, focusing on the visualizers. The visualizers were given tests designed to measure two types of imagery: spatial imagery and object imagery. Spatial imagery refers to the ability to image spatial relations, such as the layout of a garden. Object imagery refers to the ability to image visual details, features, or objects, such as a rose bush with bright red roses in the garden (Sheldon et al., 2017). The paper folding test (PFT) is designed to measure spatial imagery. Participants saw a piece of paper being folded and then pierced by a pencil (Figure 10.21a). Their task was to pick from five choices what the paper would look like when unfolded. The vividness of visual imagery questionnaire (VVIQ) was designed to measure object imagery. Participants rated, on a 5-point scale, the vividness of mental images they were asked to create. A typical item: “The sun is rising above the horizon into a hazy sky.” The results of the tests, shown in Figure 10.22, demonstrate differences between participants with a low score on the PFT (low spatial imagery) and participants with a high score (high spatial imagery). Sixty-two percent of the low spatial imagers had high scores on the VVIQ, meaning they had high object imagery, whereas 51 percent of the high spatial imagers had low scores on the VVIQ, meaning they had low object imagery.

Question 40

Individual Differences in Visual Imagery Kozhevnikov and colleagues (2007)

Answer 40

In a study designed to determine how well participants with different levels of spatial imagery performed on physics problems, Kozhevnikov and colleagues (2007) presented the picture in Figure 10.23 with the following text and questions to a group of students who had not taken any physics courses in high school or college. Frame of Reference Problem A small metal ball is being held by a magnet attached to a post on a cart. A cup is on the cart directly below the ball. The cart is moving at a constant speed as shown by the arrow in the figure. Suppose the ball falls off the magnet while the cart is in motion. Observer A stands in the cart, and Observer B stands on the road, directly opposite the post of the cart at the moment of the ball releasing. Which of the reports described below corresponds to observer A’s view of the falling ball: (a) The falling ball moves straight down. (b) The falling ball moves forward. (c) The falling ball moves backward. Which of the reports described below corresponds to observer B’s view of the falling ball: (a) The falling ball moves straight down. (b) The falling ball moves forward. (c) The falling ball moves backward. The answer: Observer A is in the cart, moving along with the ball, so they will see the ball as moving straight down into the cup. Because Observer B is standing outside the cart, they will see the falling ball move down and forward before falling into the cup. Half of the students correctly answered that Observer A would see the ball move straight down into the cup. Focusing on the students who answered correctly for observer A, Kozhevnikov and colleagues (2007) found that 70 percent of students who were high spatial imagers correctly answered that Observer B would see the ball moving down and forward, but only 18 percent of the low spatial imagers came up with the correct answer. From these results, and the results for additional physics problems, Kozhevnikov concluded that spatial ability is related to solving many types of physics problems. The results of experiments like these confirm Galton’s idea that people vary in their experience of visual imagery, and we now know that there can be variation even within the type of visual imagery—with some people better at spatial imagery than object imagery, some better at object imagery than spatial, and some good at both. Others may even have a complete lack of imagery ability, a condition known as aphantasia .

Question 41

Aphantasia

Answer 41

Aphantasia is an inability to voluntarily generate mental images. Zeman and colleagues (2015) first coined this term, combining the prefix “a” meaning “without” and the Greek word “phantasia” meaning “appearance.” While research into mental imagery dates back to the cognitive revolution, research on aphantasia is still relatively new. Therefore, we must be careful drawing conclusions from this still-evolving field of study. Here’s what we know so far. Aphantasia likely affects around 4 percent of the population (Dance, Ipser, & Simner, 2022). However, making this determination is more challenging than you might think. How do we “diagnose” someone with aphantasia? Historically, measures like the VVIQ that we have already discussed have been used to test for aphantasia. The problem is that there is a high risk of self-selected samples and self-diagnosis impacting and artificially inflating rates of aphantasia. For instance, if you believe you are a poor mental imager (“I can’t see things when I try to imagine them”) and therefore believe you have aphantasia, you are more likely to (a) participate in a study related to aphantasia and (b) answer questions so that your results indicate you have aphantasia. Current research in this area is attempting to make diagnosis more objective, which will lead to a more precise measure of the prevalence of aphantasia.

Question 42

Cognitive Impact of Aphantasia

Answer 42

Research has identified a variety of cognitive performance differences for individuals with aphantasia compared to “good imagers.” For instance, a case study of someone with aphantasia found that they had a hard time with working memory tasks that included a visual component (Jacobs, Schwarzkopf, & Silvanto, 2018). However, a study including a larger sample of individuals with aphantasia found this visual working memory deficit to be minimal (Keogh, Wicken, & Pearson, 2021). This discrepancy is likely due to the strategies used by individuals with aphantasia to complete working memory tasks. While good imagers are likely to use visual imagery during visual working memory tasks, individuals with aphantasia are likely to compensate for their lack of imagery abilities by engaging other cognitive mechanisms such as proposition (language). Aphantasia may also impact autobiographical memory (Dawes et al., 2020; Monzel et al., 2022). Recall of autobiographical memories may be less vivid compared with similar memories of individuals with high-functioning mental imagery because they cannot mentally visualize the events. Instead of recalling visual images, their memories might rely more on other sensory cues, such as verbal descriptions or emotional content. While autobiographical memory has been the focus of research so far, Monzel and colleagues suggest other types of memory may also be impacted by aphantasia. Visual search is also impacted by aphantasia. Monzel and colleagues (2021) found that individuals with aphantasia tend to react slower in visual search tasks compared to those without aphantasia. However, both groups showed similar improvements in reaction time when exposed (“primed”) to a visual characteristic of the to-be-remembered item, such as color, rather than a visual characteristic of a non-relevant item. This outcome suggests good imagers and individuals with aphantasia were influenced similarly by priming cues, indicating a shared cognitive process. In this study, however, the color of the prime may or may not have been relevant to the search task. Participants had to identify the correct target item from either two images or two words. Good imagers had a greater reduction in reaction time compared to individuals with aphantasia for the two-images condition compared to the two-words condition. When Monzel and Reuter (2023) tested these differences using real-world visual scenarios, they found that individuals with aphantasia were slower at identifying hidden objects in pictures, confirming differences in visual search abilities for good imagers compared to individuals with aphantasia.

Question 43

Why Should We Care About Mental Imagery? Using Imagery to Improve Memory

Answer 43

Imagery can play an important role in memory. How can you harness the power of imagery to help you remember things better? In Chapter 7, we considered that encoding is aided by forming connections with other information. Another principle of memory we described in Chapter 7 was that organization improves encoding. The mind tends to spontaneously organize information that is initially unorganized, and presenting information that is organized improves memory performance. Recall the visual mnemonics discussed in Chapter 7, including the method of loci and method of association. These two memory strategies utilize mental imagery to improve memory ability. For those with better mental imagery abilities, these techniques are more effective (Keoph & Pearson, 2011; Robins, 2022).

Question 44

Why Should We Care About Mental Imagery? Motor Training

Answer 44

Mental imagery can be a valuable tool in improving motor training and performance. Think back to our Olympic athletes from the beginning of this chapter. Research has demonstrated that mental imagery can enhance motor learning and performance in various domains, including sports, music, and rehabilitation. For example, athletes often use mental imagery to visualize themselves executing movements flawlessly before actually performing them in competition. This visualization helps them reinforce correct technique, build confidence, and mentally prepare for the task ahead (Iacono, Ashcroft, & Zubac, 2021; Lindsay et al., 2023). Also, musicians can use mental imagery to enhance action planning, imagine the execution of movements, and prepare for interpersonal coordination (Keller, 2012). By imagining the visual environment and scenarios associated with playing an instrument alone or with others, the benefits of practice can still be attained. While less effective than physically playing an instrument, mental imagery is still an effective tool for rehearsal (Taruffi & Kussner, 2019). In motor rehabilitation settings, mental imagery has been used to supplement physical therapy and aid in the recovery of motor function after injury or surgery. By mentally rehearsing movements, patients can maintain or even improve their motor skills while physically unable to perform them. For instance, mental imagery has been shown to improve the planning and execution of tasks for individuals recovering from a stroke (Liu et al., 2004; Bello, Winser, & Chan, 2020). Overall, while physical practice remains crucial for skill acquisition, mental imagery can serve as a valuable complementary tool to enhance learning and performance in motor tasks.