Cognitive Psychology and Its Implications, Ch. 4

Mental Imagery

Try answering these two questions:

• How many windows are in your house? • How many nouns are in the American Pledge of Allegiance?

Most people who answer these questions have the same experience. For the first

question they imagine themselves walking around their house and counting windows.

For the second question, if they do not actually say the Pledge of Alliance out loud,

they imagine themselves saying the Pledge of Allegiance. In both cases they are creating

mental images of what they would have perceived had they actually walked around

the house or said the Pledge of Allegiance.

Use of visual imagery is particularly important. As a result of our primate heritage,

a large portion of our brain functions to process visual information. Therefore, we use

these brain structures as much as we can, even in the absence of a visual signal from

the outside world, by creating mental images in our heads. Some of humankind’s most

creative acts involve visual imagery. For instance, Einstein claimed he discovered the

theory of relativity by imagining himself traveling beside a beam of light.

A major debate in this field of research has been the degree to which the processes

behind visual imagery are the same as the perceptual and attentional processes that we

considered in the previous two chapters. Some researchers (e.g., Pylyshyn, 1973, in an

article sarcastically titled “What the mind’s eye tells the mind’s brain”) have argued that

the perceptual experience that we have while doing an activity such as picturing the

windows in our house is an epiphenomenon; that is, it is a mental experience that does

not have any functional role in information processing. The philosopher Daniel Dennett

(1969) also argued that mental images are epiphenomenal—that is, that the perceptual

components of mental images are not really functional in any way:

Consider the Tiger and his Stripes. I can dream, imagine or see a striped tiger, but

must the tiger I experience have a particular number of stripes? If seeing or imagining

is having a mental image, then the image of the tiger must—obeying the rules of

images in general—reveal a definite number of stripes showing, and one should be

able to pin this down with such questions as “more than ten?”, “less than twenty?”

(p. 136)

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Verbal Imagery versus Visual Imagery | 93

Dennett’s argument is that if we are actually seeing a tiger in a mental image, we

should be able to count its stripes just like we could if we actually saw a tiger.

Because we cannot count the stripes in a mental image of a tiger, we are not having

a real perceptual experience. This argument is not considered decisive, but it does

illustrate the discomfort some people have with the claim that mental images are

actually perceptual in character.

This chapter will review some of the experimental evidence showing the ways that

mental imagery does play a role in information processing. We will define mental

imagery broadly as the processing of perceptual-like information in the absence of an

external source for the perceptual information. We will consider the following questions: • How do we process the information in a mental image? • How is imaginal processing related to perceptual processing? • What brain areas are involved in mental imagery? • How do we develop mental images of our environment and use these

to navigate through the environment?

•Verbal Imagery versus Visual Imagery

There is increasing evidence from cognitive neuroscience that several different

brain regions are involved in imagery. This evidence has come both from studies

of patients suffering damage to various brain regions and from studies of the

brain activation of normal individuals as they engage in various imagery tasks.

In one of the early studies of brain activation patterns during imagery, Roland

and Friberg (1985) identified many of the brain regions that have been investigated

in subsequent research. They had participants either mentally rehearse a

word jingle or mentally rehearse finding their way around streets in their neighborhoods.

The investigators measured changes in blood flow in various parts of

the cortex. Figure 4.1 illustrates the principal areas they identified.When participants

engaged in the verbal jingle task, there was activation in the prefrontal cortex

near Broca’s area and in the parietal-temporal region of the posterior cortex

FIGURE 4.1 Results from

Roland and Friberg’s (1985)

study of brain activation

patterns during mental imagery.

Regions of the left cortex

showed increased blood flow

when participants imagined

a verbal jingle (J) or a spatial

route (R).

Brain Structures

Anderson7e_Chapter_04.qxd 8/20/09 9:42 AM Page 93

near Wernicke’s area. As discussed in Chapter 1, patients with damage to these

regions show deficits in language processing. When participants engaged in the

visual task, there was activation in the parietal cortex, occipital cortex, and temporal

cortex. All these areas are involved in visual perception and attention, as

we saw in Chapters 2 and 3.When people process imagery of language or visual

information, some of the same areas are active as when they process actual

speech or visual information.

An experiment by Santa (1977) demonstrated the functional consequence

of representing information in a visual image versus representing it in a verbal

image. The two conditions of Santa’s experiment are shown in Figure 4.2. In

the geometric condition (Figure 4.2a), participants studied an array of three

geometric objects, arranged with one object centered below the other two.

This array had a facelike property—without much effort, we can see eyes and a

mouth. After participants studied the array, it was removed, and they had to

hold the information in their minds. They were presented with one of several

different test arrays. The participants’ task was to verify that the test array contained

the same elements as the study array, although not necessarily in the same

94 | Mental Imagery

Study

array

arrays

Test

arrays

Study

array

Identical,

same configuration

Same elements,

linear configuration

Different elements,

same configuration

Different elements,

linear configuration

Triangle Circle

Square

Triangle Circle

Square

Triangle Circle Square

Triangle Circle

Arrow

Triangle Circle Arrow

Identical,

same configuration

Same word,

linear configuration

Different words,

same configuration

Different words,

linear configuration

(a) Geometric condition

(b) Verbal condition

FIGURE 4.2 The procedure followed in Santa’s (1977) experiment demonstrating that visual

and verbal information is represented differently in mental images. Participants studied an initial

array of objects or words and then had to decide whether a test array contained the same

elements. Geometric shapes were used in (a), words for the shapes in (b).

Anderson7e_Chapter_04.qxd 8/20/09 9:42 AM Page 94

spatial configuration. Thus, participants should

have responded positively to the first two test

arrays and negatively to the last two. Santa was

interested in the contrast between the two positive

test arrays. The first was identical to the

study array (same-configuration condition). In

the second array, the elements were displayed

in a line (linear-configuration condition). Santa

predicted that participants would make a positive

identification more quickly in the first case,

where the configuration was identical—because,

he hypothesized, the mental image for the study

stimulus would preserve spatial information. The

results for the geometric condition are shown in

Figure 4.3. As you can see, Santa’s predictions were confirmed. Participants were

faster in their judgments when the geometric test array preserved the configuration

information in the study array.

The results from the geometric condition are more impressive when contrasted

with the results from the verbal condition, illustrated in Figure 4.2b.

Here, participants studied words arranged exactly as the objects in the geometric

condition were arranged. Because it involved words, however, the study stimulus

did not suggest a face or have any pictorial properties. Santa speculated that participants

would read the array left to right and top down and encode a verbal

image with the information. So, given the study array, participants would encode

it as “triangle, circle, square.” After they studied the initial array, one of the test

arrays was presented. Participants had to judge whether the words were identical.

All the test stimuli involved words, but otherwise they presented the same

possibilities as the test stimuli in the geometric condition. The two positive stimuli

exemplify the same-configuration condition and the linear-configuration

condition. Note that the order of words in the linear array was the same as it

was in the study stimulus. Santa predicted that, unlike the geometric condition,

because participants had encoded the words into a linearly ordered verbal image,

they would be fastest when the test array was linear. As Figure 4.3 illustrates,

his predictions were again confirmed.

Different parts of the brain are involved in verbal and visual imagery,

and they represent and process information differently.

•Visual Imagery

Most of the research on mental imagery has involved visual imagery, and this

will be the principal focus of this chapter. One function of mental imagery is to

anticipate how objects will look from different perspectives. People often have

the impression that they rotate objects mentally to achieve perspective. Roger

Shepard and his colleagues have been involved in a long series of experiments

Visual Imagery | 95

Geometric

Verbal

Reaction time (s)

1.25

1.15

Same

configuration

Linear

configuration

FIGURE 4.3 Results from

Santa’s (1977) experiment. The

data confirmed two of Santa’s

hypotheses: (1) In the geometric

condition, participants would

make a positive identification

more quickly when the configuration

was identical than when

it was linear, because the visual

image of the study stimulus

would preserve spatial information.

(2) In the verbal condition,

participants would make a

positive identification more

quickly when the configuration

was linear than when it was

identical, because participants

had encoded the words from

the study array linearly, in

accordance with normal reading

order in English.

Anderson7e_Chapter_04.qxd 8/20/09 9:42 AM Page 95

on mental rotation. Their research was among the first to study the functional

properties of mental images, and it has been very influential. It is interesting to

note that this research was inspired by a dream (Shepard, 1967): Shepard awoke

one day and remembered having visualized a 3-D structure turning in space.

He convinced Jackie Metzler, a first-year graduate student at Stanford, to study

mental rotation, and the rest is history.

Their first experiment was reported in the journal Science (Shepard &

Metzler, 1971). Participants were presented with pairs of 2-D representations

of 3-D objects, like those in Figure 4.4. Their task was to determine whether the

objects were identical except for orientation. The two objects in Figure 4.4a

are identical, as are the two objects in Figure 4.4b, but in both cases the pairs

are presented at different orientations. Participants reported that to match the

two shapes, they rotated one of the objects in each pair mentally until it was

congruent with the other object. There is no way to rotate one of the objects in

Figure 4.4c so that it is identical with the other.

The graphs in Figure 4.5 show the times required for participants to decide

that the members of pairs were identical. The reaction times are plotted as a

function of the angular disparity between the two objects presented. The angular

disparity is the amount one object would have to be rotated to match the other

object in orientation. Note that the relationship is linear—for every increment

in amount of rotation, there is an equal increment in reaction time. Reaction

time is plotted for two different kinds of rotation. One is for 2-D rotations

(Figure 4.4a), which can be performed in the picture plane (i.e., by rotating the

page); the other is for depth rotations (Figure 4.4b), which require the participant

to rotate the object into the page. Note that the two functions are very

similar. Processing an object in depth (in three dimensions) does not appear

to have taken longer than processing an object in the picture plane. Hence,

participants must have been operating on 3-D representations of the objects in

both the picture-plane and depth conditions.

These data might seem to indicate that participants rotated the object in a

3-D space within their heads. The greater the angle of disparity between the two

objects, the longer participants took to complete the rotation. Though the

participants were obviously not actually rotating a real object in their heads,

the mental process appears to be analogous to physical rotation.

96 | Mental Imagery

(a) (b) (c)

FIGURE 4.4 Stimuli in the Shepard and Metzler (1971) study on mental rotation. (a) The

objects differ by an 80° rotation in the picture plane (two dimensions). (b) The objects differ

by an 80° rotation in depth (three dimensions). (c) The objects cannot be rotated into

Anderson7e_Chapter_04.qxd 8/20/09 9:42 AM Page 96

There has been a great deal of subsequent research examining the mental

rotation of all sorts of different objects. The typical finding is that the time

required to complete a rotation does vary with the angle of disparity. In recent

years, there have been a number of brain-imaging studies that looked at what

regions are active during mental rotation. Consistently, the parietal region

(roughly the region labeled R at the upper back of the brain in Figure 4.1) has

been activated across a range of tasks. This finding corresponds with the results

we reviewed in Chapter 3 showing that the parietal region is important in spatial

attention. Some tasks involve activation of other areas. For instance, Kosslyn,

DiGirolamo, Thompson, and Alpert (1998) found that imagining the rotation of

one’s hand produced activation in themotor cortex.

Neural recordings of monkeys have provided some evidence about neural

representation during mental rotation involving hand movement. Georgopoulos,

Lurito, Petrides, Schwartz, and Massey (1989) had monkeys perform a task in

which they moved a handle at a specific angle in response to a given stimulus. In

the base condition, monkeys just moved the handle to the position of the stimulus.

Georgopoulos et al. found cells that fired for particular positions. So, for

instance, there were cells that fired most strongly when the monkey was moving to

the 9 o’clock position and other cells that responded most stronglywhen the monkey

moved to the 12 o’clock position. In the rotation condition, the monkeys had

to move the handle to a position rotated some number of degrees from the stimulus.

For instance, if the monkeys had to move the handle 90° counterclockwise and

the stimulus appeared at the 12 o’clock position, they would have to move the

handle to 9 o’clock. If the stimulus appeared at the 6 o’clock position, they would

have to move to 3 o’clock. The greater the angle, the longer it took the monkeys

Visual Imagery | 97

Angle of rotation (degrees)

(a) (b)

0 40 80 120 160

Mean reaction (s)

0 40 80 120 160

FIGURE 4.5 Results of the Shepard and Metzler (1971) study on mental rotation. The mean

time required to determine that two objects have the same 3-D shape is plotted as a function

of the angular difference in their portrayed orientations. (a) Plot for pairs differing by a rotation

in the picture plane (two dimensions). (b) Plot for pairs differing by a rotation in depth (three

Anderson7e_Chapter_04.qxd 8/20/09 9:42 AM Page 97

to initiate the movement, suggesting that this task involved a mental rotation

process to achieve the transformation. In this rotation condition, Georgopoulos

et al. found that various cells fired at different times during the transformation.At

the beginning of a transformation trial, when the stimulus was presented, the cells

that fired most were associated with a move in the direction of the stimulus.By the

end of a transformation trial, when the monkey actually moved the handle, maximumactivity

occurred in cells associated with the movement. Between the beginning

and the end of the trial, cells representing intermediate directions were most

active. These results suggest that mental rotation involves gradual shifts of firing

from cells that encode the initial stimulus to cells that encode the transformed

stimulus or, in this case, the transformed response.

When people must transform the orientation of a mental image to make

a comparison, they rotate its representation through the intermediate

positions until it achieves the desired orientation.

Image Scanning

Something else we often do with mental images is to scan them looking for some

critical information. For instance, when people are asked how many windows

there are in their houses (the task described at the beginning of this chapter),

many report mentally going through the house visually as they count the

windows. Researchers have been interested in the degree to which people are

actually scanning perceptual representations in such tasks, as opposed to just

retrieving abstract information. For instance, are we really “seeing” each window

in the room or are we just remembering how many windows are in the room?

Brooks (1968) performed an important series of experiments on the scanning

of visual images. He had participants scan imagined diagrams such as the

one shown in Figure 4.6. For example, the participant was to scan around an

imagined block F from a prescribed starting point and in a prescribed direction,

categorizing each corner of the block as a point in the top or bottom (assigned a

yes response) or as a point in between (assigned a no response). In the example

(beginning with the starting corner), the correct sequence of responses is yes, yes,

yes, no, no, no, no, no, no, yes. For a nonvisual contrast task, Brooks also gave

participants sentences such as “A bird in the hand is not in the bush.” Participants

had to scan the sentence while holding it in memory, deciding whether

each word was a noun or not. A second experimental variable was how participants

made their responses. Participants responded in one of three ways:

(1) said yes or no; (2) tapped with the left hand for yes and with the right hand

for no; or (3) pointed to successive Y’s or N’s on a sheet of paper such as the

one shown in Figure 4.7. The two variables of stimulus material (diagram or

sentence) and output mode were crossed to yield six conditions.

Table 4.1 gives the results of Brooks’s experiment in terms of the mean

time spent in classifying the sentences or diagrams in each output condition.

The important result for our purposes is that participants took much longer

for diagrams in the pointing condition than in any other condition, but this

was not the case when participants were working with sentences. Apparently,

98 | Mental Imagery

FIGURE 4.6 An example of a

simple block diagram that Brooks

used to study the scanning of

mental images. The asterisk and

arrow show the starting point

and the direction for scanning

the image. (From Brooks, 1968.

Reprinted by permission of the publisher.

Association.)

Anderson7e_Chapter_04.qxd 8/21/09 6:58 PM Page 98

scanning a physical visual array conflicted with scanning a mental array.

This result strongly reinforces the conclusion that when people are scanning

a mental array, they are scanning a representation that is analogous

to a physical visual array. Requiring the person simultaneously to engage

in a conflicting scanning action on an external physical visual array disrupts

the mental scan.

One might think that Brooks’s result was due to the conflict between

engaging in a visual pointing task and scanning a visual image.

Subsequent research makes it clear, however, that the interference is not a

result of the visual character of the task per se. Rather, the problem is spatial

and not specifically visual; it arises from the conflicting directions in

which participants had to scan the physical visual array and the mental

image. For instance, in another experiment, Brooks found evidence of

similar interference when participants had their eyes closed and indicated

yes or no by scanning an array of raised Y’s and N’s with their fingers. In

this case, the actual stimuli were tactile, not visual. Thus, the conflict is

spatial, not specifically visual.

Baddeley and Lieberman (reported in Baddeley, 1976) performed an

experiment that further supports the view that the nature of the interference

in the Brooks task is spatial rather than visual. Participants were

required to perform two tasks simultaneously. All participants performed

the Brooks letter-image task. However, participants in one group simultaneously

monitored a series of stimuli of two possible brightnesses and had

to press a key whenever the brighter stimulus appeared. This task involved

the processing of visual but not spatial information. Participants in the

other condition were blindfolded and seated in

front of a swinging pendulum. The pendulum

emitted a tone and contained a photocell. Participants

were instructed to try to keep the beam of

a flashlight on the swinging pendulum. Whenever

they were on target, the photocell caused the

tone to change frequency, thus providing auditory

feedback. This test involved the processing

of spatial but not visual information. The spatial

auditory tracking task produced far greater

impairment in the image scanning task than did

the brightness judgment task. This result also

indicates that the nature of the impairment in

the Brooks task was spatial, not visual.

People suffer interference in scanning a mental image if they have to

simultaneously process a conflicting perceptual structure.

Visual Comparison of Magnitudes

A fair amount of research has focused on the way people judge the visual details

of objects in their mental images. One line of research has asked participants

Visual Imagery | 99

FIGURE 4.7 A sample output sheet of

the pointing condition in Brooks’s study

of mental image scanning. The letters

are staggered to force careful visual

monitoring of pointing. (From Brooks, 1968.

by the Canadian Psychological Association.)

TABLE 4.1

Results of Brooks’s (1968) Experiment Showing Conflict

Between Mental Array and Visual Array Scanning

Mean Response Time (s)

by Output Mode

Stimulus Material Pointing Tapping Vocal

Diagrams 28.2 14.1 11.3

Sentences 9.8 7.8 13.8

Canadian Psychological Association.

Anderson7e_Chapter_04.qxd 8/20/09 9:42 AM Page 99

to discriminate between objects based on some dimension such as size. This

research has shown that when participants try to discriminate between two

objects, the time it takes them to do so decreases continuously as the difference

in size between the two objects increases.

Moyer (1973) was interested in the speed with which participants could

judge the relative size of two animals from memory. For example, “Which is

larger, moose or roach?” and “Which is larger, wolf or lion?”Many people report

that in making these judgments, particularly for the items that are similar in

size, they experience images of the two objects and seem to compare the sizes

of the objects in their images.

Moyer also asked participants to estimate the absolute size of these animals.

He plotted the time required to compare the imagined sizes of two animals

as a function of the difference between the two animals’ estimated sizes.

Figure 4.8 reproduces these data. The individual points represent

comparisons between pairs of items. In general, the

judgment times decreased as the difference in estimated size

increased. The graph shows that judgment time decreases linearly

with increases in differences in the size of the animals.

Note, however, that the differences have been plotted logarithmically.

A log-difference scale makes the distance between small

differences large relative to the same distances between large

differences. Thus, the linear relationship in the graph means

that increasing the size difference has a diminishing effect on

reaction time.

Significantly, very similar results are obtained when people

visually compare physical size. For instance, D. M. Johnson

(1939) asked participants to judge which of two simultaneously

presented lines was longer. Figure 4.9 plots participant judgment

time as a function of the log difference in line length. Again, a

linear relation is obtained. It is reasonable to expect that the

100 | Mental Imagery

1.4

Mean reaction time (s)

Difference in line length (mm)

2.3

3.2

2.9

1.7

2.0

2.6

1 2 3 4 6 8

1.5

1.4

1.3

1.2

1.1

1.0

0.9

0.8

0.10 1.10 2.10

Estimated difference in animal size

Mean reaction time (s)

FIGURE 4.8 Results from Moyer’s experiment demonstrating that

when people try to discriminate between two objects, the time it

takes them to do so decreases as the difference in size between

the two objects increases. Participants were asked to compare the

imagined sizes of two animals. The mean time required to judge

which of two animals is larger is plotted as a function of the estimated

difference in size of the two animals. The difference measure

is plotted on the abscissa in a logarithmic scale. (From Moyer, 1973.

FIGURE 4.9 Results from the

D. M. Johnson (1939) study

demonstrating that making

mental comparisons involves

difficulties of discrimination

similar to those involved in

making perceptual comparisons.

Participants compared the

lengths of two lines. The mean

time required to judge which

line was longer is plotted as a

function of the difference in line

length. The difference measure

is plotted on the abscissa in

a logarithmic scale.

Anderson7e_Chapter_04.qxd 8/20/09 9:42 AM Page 100

more similar the lengths being compared are, the longer perceptual judgments

will take, because telling them apart is more difficult under such circumstances.

The fact that similar functions are obtained when mental objects are compared

indicates that making mental comparisons involves the same process as those

involved in perceptual comparisons.

People experience greater difficulty in judging the relative size of two pictures

or of two mental images that are similar in size.

Are Visual Images Like Visual Perception?

Research has been done to determine to what degree visual imagery is like

perception. In one experiment, Finke, Pinker, and Farah (1989) set out to

determine the degree to which people were able to recognize the images they

constructed in the same way they would be able to recognize objects they saw.

These researchers asked participants to create mental images and then engage

in a series of transformations of those images. Here are two examples of the

problems that they read to their participants:

• Imagine a capital letter N. Connect a diagonal line from the top right

corner to the bottom left corner. Now rotate the figure 90° to the right.

What do you see? • Imagine a capital letter D. Rotate the figure 90° to the left. Now place a

capital letter J at the bottom.What do you see?

Participants closed their eyes and tried to imagine these transformations as

they were read to them. The participants were able to recognize their composite

images just as if they had been presented with them on a screen. In the first

example, they saw an hourglass; in the second, an umbrella. The ability to

perform such tasks illustrates an important function of imagery: It enables us

to construct new objects in our minds and inspect them. It is just this sort of

visual synthesis that structural engineers or architects must perform as they

design new bridges or buildings.

The Finke et al. (1989) study shows that we can make judgments about

imagined objects and come to the same conclusions as we would about seen objects.

But are these imagined objects really the same as seen objects? Researchers

have been doing studies to see whether subtle properties associated with visual

perception are also reproduced in mental images. For instance, Wallace (1984)

did an experiment to study the Ponzo illusion (Berbaum & Chung,

1981) illustrated in part (a) of Figure 4.10: Even though the two horizontal

lines have the same length, the upper one seems longer. In the

experiment, participants were first shown the converging lines in

part (b) and then shown the two horizontal lines in part (c) and

asked to imagine them together so that the top horizontal line

touched the two diagonals. They were asked to compare the length

of the two horizontal lines in their mental images. Participants rated

as high in imagery ability reported as strong an illusion for their

mental image as for the actual stimulus in part (a). Thus, it appears

Visual Imagery | 101

(a) (b) (c)

FIGURE 4.10 The Ponzo illusion

is illustrated in part (a): Even

though they have the same

length, the upper horizontal

line seems longer. Parts (b) and

(1984) used to study the illusion

in imagery. Participants imagined

the parts superimposed so

that the diagonal lines in

(b) just touched the horizontal

lines in (c). (From Wallace, 1984.

Reprinted by permission of the publisher.

Anderson7e_Chapter_04.qxd 8/20/09 9:43 AM Page 101

that the imagery system can reproduce a detailed visual illusion, supporting

the apparent equivalence between imagery and perception.

Chambers and Reisberg (1985) reported a study that seemed to

indicate differences between a mental image and visual perception of the

real object. Their research involved the processing of reversible figures,

such as the duck-rabbit shown in Figure 4.11. Participants were briefly

shown the figure and asked to form an image of it. They had only

enough time to form one interpretation of the picture before it was removed,

but they were asked to try to find a second interpretation. Participants

were not able to do this. Then they were asked to draw the image

on paper to see whether they could reinterpret it. In this circumstance,

they were successful. This result suggests that visual images differ from pictures

in that one can interpret visual images only in one way, and it is not possible to

find an alternative interpretation of the image.

Subsequently, Peterson, Kihlstrom, Rose, and Gilsky (1992) were able to get

participants to reverse mental images by giving them more explicit instructions.

For instance, participants might be told how to reverse another figure or be

given the instruction to consider the back of the head of the animal in their

mental image as the front of the head of another animal. Thus, it seems apparent

that although it may be more difficult to reverse an image than a picture,

both can be reversed. In general, it seems harder to process an image than the

actual stimulus. Given a choice, people will almost always choose to process an

actual picture rather than imagine it. For instance, players of Tetris prefer to

rotate shapes on the screen to find an appropriate orientation rather than rotate

them mentally (Kirsh & Maglio, 1994).

It is possible to make many of the same kinds of detailed judgments about

mental images that we make about things we actually see, though it is more

difficult.

Visual Imagery and Brain Areas

Brain imaging studies indicate that the same regions are involved in perception

as in mental imagery. As already noted, the parietal regions that are involved in

attending to locations and objects (last chapter) are also involved in mental

rotation. A study by O’Craven and Kanwisher (2000) illustrates how closely the

brain areas activated by imagery correspond to the brain areas activated by

perception. Recall from Chapter 2 that the fusiform region of the temporal cortex

responds preferentially to faces. There is another region of the temporal

cortex, the parahippocampal place area (PPA), that responds preferentially to

pictures of locations. O’Craven and Kanwisher asked participants either to view

faces and scenes or to imagine faces and scenes. The same areas were active

when the participants were seeing as when they were imagining. Figure 4.12

compares activation in the fusiform face area (FFA) with activation in the PPA.

Every time the participants viewed or imagined a face, there was increased activation

in the FFA, and this activation went away when they processed places.

Conversely, when they viewed or imagined scenes, there was activation in the

102 | Mental Imagery

FIGURE 4.11 The ambiguous

duck-rabbit figure used in

Chambers and Reisberg’s study

of the processing of reversible

figures. (From Chambers & Reisberg,

1985. Reprinted by permission of the

Psychological Association.)

Anderson7e_Chapter_04.qxd 8/20/09 9:43 AM Page 102

PPA that went away when they processed faces. The responses during imagery

were very similar to the responses during perception, although a little weaker.

The fact that the response was weaker during imagery is consistent with the

behavioral evidence we have viewed suggesting that it is more difficult to process

an image than a real perception.

There are many studies like these that show the involvement of cortical

regions that are further along in the visual processing stream, but the evidence is

less clear about activation in the primary visual cortex (areas 17 and 18) where

visual information first reaches the brain. The O’Craven and Kanwisher study

found activation in the primary visual cortex during imagery. Such results are

important because they suggest that visual imagery includes relatively low-level

perceptual processes. However, activation has not always been found in the

primary visual cortex. For instance, the Roland and Friberg study illustrated

in Figure 4.1 did not find activation in this region (see also Roland, Eriksson,

Stone-Elander, & Widen, 1987). Kosslyn and Thompson (2003) reviewed

59 brain-imaging studies that looked for activation in early visual areas. About

half of these studies find activation in early visual areas and half do not.

Visual Imagery | 103

−0.5

0.0

Signal change (%) Signal change (%)

0.5

1.0

1.5

2.0

−1.0

−0.5

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Perception Imagery Perception Imagery

FFA

PPA

FIGURE 4.12 Results from the O’Craven and Kanwisher study showing that visual images are

processed in the same way as actual perceptions and by many of the same neural structures.

Although participants alternately perceived (or imagined) faces and places, brain activation

was seen in the fusiform face area (FFA, upper panel) and the parahippocampal place area

Journal of Cognitive Neuroscience.)

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Their analysis suggests that the studies that find activation in these early visual

areas tend to emphasize high-resolution details of the images and tend to focus

on shape judgments. As an instance of one of the positive studies, Kosslyn et al.

(1993) did find activation in area 17 in a study where participants were asked

to imagine block letters. In one of their experiments, participants were asked to

imagine large versus small letters. In the small-letter condition, activity in the

visual cortex occurred in a more posterior region closer to where the center of

the visual field is represented (recall that the visual field is topographically

organized—see Figure 2.6). This would make sense because a small image

would be more concentrated at the center of the visual field.

Imaging studies like these show that perceptual regions of the brain are

active when participants are engaged in mental imagery, but they do not

establish whether these regions are actually critical to imagery. To return to the

epiphenomenon critique at the beginning of the chapter, it could be that the

activation plays no role in the actual tasks being performed. A number of experiments

now have used transcranial magnetic stimulation (TMS—see Figure

1.13) to investigate the causal role of these regions in the performance of

the underlying task. For instance, Kosslyn et al. (1999) presented participants

with 4-quadrant arrays like those in Figure 4.13 and asked them to form a mental

image of the array. Then, with the array removed, participants had to use

their image to answer questions like “Which has longer stripes: Quadrant 1 or

Quadrant 2?” or “Which has more stripes: Quadrant 1 or Quadrant 4?” Application

of TMS to primary visual area 17 significantly increased the time they

took to answer these questions. Thus, it seems that these visual regions do play

a causal role in mental imagery, and temporarily deactivating them results in

impaired information processing.

When performing a visual imFagery task, there is activation in brain regions

involved in visual perception, and disruption of these regions results in

disruption of the imagery task.

104 | Mental Imagery

FIGURE 4.13 Illustration of stimuli used in Kosslyn et al. (1999).

The numbers 1, 2, 3, and 4 were used to label the four quadrants,

each of which contained a set of stripes. After memorizing the

display, the participants closed their eyes, visualized the entire

display, heard the names of two quadrants, and then heard

the name of a comparison term (for example, “length”); the

participants then decided whether the stripes in the first-named

quadrant had more of the named property than those in the

second.

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Imagery Involves Both Spatial and Visual Components

We have reviewed the Brooks (1968) research indicating that people are sensitive

to the spatial structure of their mental images and the Moyer (1973) research

indicating that people process visual details such as size in their mental images.

The distinction between the spatial and visual attributes of imagery has proved

important in recent research.We can encode the position of objects in space by

seeing where they are, by feeling where they are, or by hearing where they are.

Such encodings use a common spatial representation that integrates information

that comes in from any sensory modality. On the other hand, certain aspects of

visual experience, such as color, are unique to the visual modality and seem separate

from spatial information. Thus, imagery involves both spatial and visual

components. In the discussion of the visual system in Chapter 2, we reviewed

the evidence that there is a “where” pathway for processing spatial information

and a “what” pathway for processing object information (see Figure 2.1). Corresponding

to this distinction, there is evidence that the parietal regions support

the spatial component of visual imagery, whereas the temporal lobe supports the

visual aspects (see Figure 4.1). We have already noted that mental rotation, a

spatial task, tends to produce activation in the parietal cortex. Similarly, temporal

structures are activated when people imagine visual properties of objects

(Thompson & Kosslyn, 2000).

Patient studies of imagery also support this association of spatial imagery

with parietal areas of the brain and visual imagery with temporal areas.

Levine, Warach, and Farah (1985) compared two patients, one who suffered

bilateral parietal-occipital damage and the other who suffered bilateral inferior

temporal damage. The patient with parietal damage could not describe the

locations of familiar objects or landmarks from memory, but he could

describe the appearance of objects. The patient with temporal damage had

an impaired ability to describe the appearance of objects but could describe

their locations.

Farah, Hammond, Levine, and Calvanio (1988) carried out more detailed

testing of the patient with temporal damage. They compared his performance

on a wide variety of imagery tasks to that of normal participants. They found

that he showed deficits on only a subset of these tasks: ones in which he had to

judge color (“What is the color of a football?”), sizes (“Which is bigger, a popsicle

or a pack of cigarettes?”), the lengths of animals’ tails (“Does a kangaroo

have a long tail?”), and whether two states in the United States had similar

shapes. In contrast, he did not show any deficit in performing tasks that seemed

to involve a substantial amount of spatial processing: mental rotation, image

scanning, letter scanning (as in Figure 4.7), or judgments of where one U.S.

state was relative to another state. Thus, temporal damage seemed to affect only

those imagery tasks that required access to visual detail, not those that required

spatial judgments.

Neuropsychological evidence suggests that imagery of spatial information

is supported by parietal structures, and imagery of objects and their visual

properties is supported by temporal structures.

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Cognitive Maps

Another important function of visual imagery is to help us figure out and

remember the spatial structure of our environment. Our imaginal representations

of the world are often referred to as cognitive maps. The connection

between imagery and action is particularly apparent in cognitive maps. We

often find ourselves imagining our environment as we plan how we will get

from one location to another.

An important distinction can be made betweeen routemaps and survey maps

(Hart &Moore, 1973).A route map is a path that indicates specific places but contains

no 2-D information. It can even be a verbal description of a path (“Straight

until the light, then turn left, two blocks later at the intersection . . .”). Thus,with a

pure route map, if your route from location 1 to location 2 were blocked, you

would have no general idea of where location 2 was, and so youwould be unable to

construct a detour.Also, if you knew (in the sense of a route map) two routes from

a location, you would have no idea whether these routes formed a 90° angle or a

120° angle with respect to each other. A survey map, in contrast, contains this information,

and is basically a spatial image of the environment.When you ask for

directions from typical online mapping services, they will provide both a route

map and a survey map to support both mental representations of space.

Thorndyke and Hayes-Roth (1982) investigated workers’ knowledge of the

Rand Corporation Building (Figure 4.14), a large, maze-like building in Santa

106 | Mental Imagery

Northwest

lobby

Computer center

Administrative

conference

room

East lobby

Cashier

Snack bar

Common

room

South

lobby

First-floor building plan

The Rand Corporation

Supply

room

Feet

0 50 100

W E

FIGURE 4.14 The floor plan for part of the Rand Corporation Building in Santa Monica, California.

Thorndyke and Hayes-Roth studied the ability of secretaries to find their way around the building.

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Monica, California. People in the Rand Building quickly acquire the ability to

find their way from one specific place in the building to another—for example,

from the supply room to the cashier. This knowledge represents a route map.

Typically, though, workers had to have years of experience in the building before

they could make such survey-map determinations as the direction of the lunchroom

from the photocopy room.

Hartley, Maguire, Spiers, and Burgess (2003) looked at the different brain

activity when people used these two types of representations. They had participants

navigate virtual reality towns under one of two conditions. In one condition,

called route-following, participants learned to follow a fixed path through

the town. In the other condition, called way-finding, participants first freely

explored the town and then had to find their way between locations. The fMRI

activation was compared when engaged in the route-following or way-finding

tasks. The results on the experiment are illustrated in Color Plate 4.1. In the

way-finding task, participants showed greater activation in a number of regions

found in other studies of visual imagery including the parietal cortex. Also,

they found greater activation in the hippocampus (see Figure 1.7), a region that

has been implicated in navigation in many species. In contrast, in the routefollowing

task participants showed greater activation in more anterior regions

motor regions. It would seem that the survey map is more like a visual image

and the route map is more like an action plan. This is a distinction that is supported

in other fMRI studies of route maps versus survey maps (e.g., Shelton &

Gabrieli, 2002).

Our knowledge of our environment can be represented in either survey maps

that emphasize spatial information or route maps that emphasize action

information.

Egocentric and Allocentric Representations of Space

Navigation becomes difficult when we must tie together multiple different

representations of space. In particular, we often need to relate the way space

appears as we perceive it to some other representation of space, such as a cognitive

map. The representation of “space as we see it” is referred to as an egocentric

representation. Figure 4.15 illustrates an egocentric representation that one might

have upon entering Camp Snoopy at the Mall of America in Bloomington,

Minnesota. Even young children have little difficulty understanding how to navigate

in space as they see it—if they see an object they want, they go for it. Problems

arise when one wants to relate what one sees to such representations of the

space as cognitive maps, be they route maps or survey maps. Similar problems

arise when one wants to deal with physical maps, such as the map of Camp

Snoopy shown in Figure 4.16. This kind of map is referred to as an allocentric

representation because it is not specific to a particular viewpoint, though, as is

true of most maps, north is oriented to the top of the image. Try to identify which

building on the map corresponds to the circled building in Figure 4.15, assuming

Visual Imagery | 107

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108 | Mental Imagery

FIGURE 4.16 An allocentric

representation of Camp Snoopy.

(Courtesy of Camp Snoopy/Bob Cole.)

that the viewpoint is the one of the stick figure illustrated

in Figure 4.16.When people try to make such judgments,

the degree to which the map is rotated from their actual

viewpoint has a large effect. Indeed, people will often

rotate a physical map so that it is oriented to correspond

to their point of view. The map in Figure 4.16 would have

to be rotated approximately 90º counterclockwise to be

oriented with the representation shown in Figure 4.15.

When it is not possible to rotate a map physically,

people show an effect of the degree of misorientation that

is much like the effect we see for mental rotation (e.g.,

Boer, 1991; Easton & Sholl, 1995; Gugerty, deBoom,

Jenkins, & Morley, 2000; Hintzman, O’Dell, & Arndt,

1981). Figure 4.17 shows a recent result from a study by Gunzelmann and

Anderson (2002), who looked at the time required to find an object on a standard

map (i.e., north oriented to the top) as a function of the viewer’s location.

When the viewer is located to the south, looking north, it is easier to find the

object than when the viewer is north looking south, just the opposite of the

map orientation. Some people describe imagining themselves moving around

the map, others talk about rotating what they see, and still others report using

verbal descriptions (“to the left of Snoopy, before the Ferris wheel”). The fact

that the angle of disparity in this task has as great an effect as it does in mental

rotation has led many researchers to believe that the processes and representations

involved in such navigational tasks are similar to the processes and representations

involved in mental imagery.

Physical maps seem to differ from cognitive maps in one important way:

Physical maps show the effects of orientation, and cognitive maps do not. For

FIGURE 4.15 An egocentric

representation of Camp Snoopy

at the Mall of America. (Courtesy

of Camp Snoopy/Bob Cole.)

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example, imagine yourself standing against various walls of your bedroom, and

point to the location of the front door of your home or apartment. Most people

can do this equally well no matter which position they take. In contrast, when

given a map like the one shown in Figure 4.16, people find it much easier to point

to various objects on the map if they are oriented in the same way the map is.

Recordings from single cells in the hippocampal region (inside the temporal

lobe) of rats suggest that the hippocampus plays an important role in maintaining

an allocentric representation of the world. There are place cells in the

hippocampus that fire maximally when the animal is in a particular location in

its environment (O’Keefe & Dostrovsky, 1971). Similar cells have been found in

recordings from human patients in a procedure to map out the brain before surgery

to control epilepsy (Ekstrom et al., 2003). Brain-imaging studies have shown

that when humans are navigating their environment, there is high hippocampal

activation (Maguire et al., 1998). Another study (Maguire et al., 2000) showed

that the hippocampal volume of London taxi drivers was greater than that of

people who didn’t drive taxis and increased with the length of time they had been

taxi drivers. It takes about 3 years of hard training to gain a knowledge of London

streets adequate to become a successful taxi driver, and this training appears to

have an impact on the structure of the brain. The amount of activation in hippocampal

structures has also been shown to correlate with age-related differences

in navigation skills (Pine et al., 2002) and may relate to gender differences in

navigational ability (Gron, Wunderlich, Spitzer, Tomczak, and Riepe, 2000).

These regions include the PPA, which O’Craven and Kanwisher (2000) found

active when participants imagined places (see Figure 4.12).

Although it appears that the hippocampus is important in supporting

allocentric representations, it seems that the parietal cortex is particularly

important in supporting egocentric representations (Burgess, 2006). In one

fMRI imaging study comparing egocentric and allocentric spatial processing

(Zaehle et al., 2007), participants where asked to make judgments that emphasized

either an allocentric or an egocentric perspective. In the allocentric conditions,

participants would read a description like “The blue triangle is to the left

of the green square. The green square is above the yellow triangle. The yellow

Visual Imagery | 109

S SW W NW N NE E SE S

0.0

0.5

1.5

1.0

2.0

2.5

3.0

3.5

Time to find object on map (s)

Direction in which viewer is looking

FIGURE 4.17 Results from

Gunzelmann and Anderson’s

study to determine how much

effect the angle of disparity

between a standard map

(looking north) and the viewer’s

viewpoint has on people’s

ability to find an object on

the map. The time required for

participants to identify the

object is plotted as a function

of the difference in orientation

between the map and the

egocentric viewpoint. (After

Gunzelmann & Anderson, 2002. Adapted

by Erlbaum.)

Anderson7e_Chapter_04.qxd 8/20/09 9:43 AM Page 109

triangle is to the right of the red circle.” Then they would be asked a question

like “Is the blue triangle above the red circle?” In the egocentric condition, they

would read a description like “The blue circle is in front of you. The yellow

circle is to your right. The yellow square is to the right of the yellow circle.”

They would then be asked a question like “Is the yellow square to your right?”

There was greater hippocampal activation when participants were answering

questions in the allocentric condition than in the egocentric condition.

Although there was considerable parietal activation in both conditions, the egocentric

condition was distinguished by greater parietal activation.

Our representation of space includes both allocentric representations of

where objects are in the world and egocentric representations of where they

are relative to ourselves.

Map Distortions

Our mental maps often have a hierarchical structure in which smaller regions

are organized within larger regions. For instance, the structure of my bedroom

is organized within the structure of my house, which is organized within the

structure of my neighborhood, which is organized within the structure of Pittsburgh.

Consider your mental map of the United States. It is probably divided

into regions, and these regions into states, and cities are presumably pinpointed

within the states. It turns out that certain systematic distortions arise because

of the hierarchical structure of these mental maps. Stevens and Coupe (1978)

documented a set of common misconceptions about North American geography.

Consider the following questions taken from their research:

• Which is farther east: San Diego or Reno? • Which is farther north: Seattle or Montreal? • Which is farther west: the Atlantic or the Pacific entrance to the Panama

Canal?

The first choice is the correct answer in each case, but most people hold the

wrong opinion. Reno seems to be farther east because Nevada is east of California,

but this reasoning does not account for the westward curve in California’s

coastline. Montreal seems to be north of Seattle because Canada is north of the

United States, but the border dips south in the east. And the Atlantic is certainly

east of the Pacific—but consult a map if you need to be convinced about the

location of the entrances to the Panama Canal. The geography of North America

is quite complex, and people resort to abstract facts about relative locations of

large physical bodies (e.g., California and Nevada) to make judgments about

smaller locations (e.g., San Diego and Reno).

Stevens and Coupe were able to demonstrate such confusions with

experimenter-created maps. Different groups of participants learned the maps

illustrated in Figure 4.18. The important feature of the incongruent maps is that

the relative locations of the Alpha and Beta counties are inconsistent with the

locations of the X and Y cities. After learning the maps, participants were asked a

series of questions about the locations of cities, including “Is X east or west of Y?”

110 | Mental Imagery

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Visual Imagery | 111

for the left-hand maps and “Is X north or south of Y?” for the right-hand maps.

On these questions, participants were in error 18% of the time for the congruent

maps and 15% percent of the time for the homogeneous maps—but 45% of the

time for the incongruent maps. Participants were using information about the

locations of the counties to help them remember the city locations. This reliance

Dimension tested

Alpha

County

Beta

County

Congruent

Horizontal

Vertical

Alpha

County

Beta

County

X Y

Alpha

County

Beta

County

Alpha

County

Beta

County

Homogeneous

Incongruent

FIGURE 4.18 Maps studied by participants in the experiments of Stevens and Coupe, which

demonstrated the effects of higher order information (location of county lines) on participants’ recall

Anderson7e_Chapter_04.qxd 8/20/09 9:43 AM Page 111

on higher order information led them to make errors, just as similar reasoning

can lead to errors in answering questions about North American geography.

When people have to work out the relative positions of two locations, they

will often reason in terms of the relative positions of larger areas that contain

the two locations.

Translating Words to Images

Another important use of spatial cognition involves the creation of a mental

image when we hear a word description of a spatial structure. This happens, for

instance, when we process directions, read a description of an event, or hear a

sportscast. The British psychologist Alan Baddeley reported that he was not able

to drive while trying to follow an American football game on the radio because

of the conflicting imagery. To get an idea of how difficult it can be to construct

a spatial image from words, try reading the description in Table 4.2.

Franklin and Tversky (1990) presented participants with such stories. After

the participants read the stories, they were asked to reorient themselves based

on descriptions such as

As you remain where you are on the balcony, you turn your body 90 degrees

to your right, and you now face the lamp. You look again at the short, rigid

pole by which it is fixed to the wall. Perhaps this is a precautionary feature in

case of earthquake.

Then they were asked to judge what was in a specific direction. For instance,

on different trials they would be asked what is on the right, on the left, above,

below, behind, or in front of them.

112 | Mental Imagery

TABLE 4.2

Description Read by Participants in Franklin and Tversky’s (1990) Experiment

You are hob-nobbing at the opera. You came tonight to meet and chat with

interesting members of the upper class. At the moment, you are standing next to

the railing of a wide, elegant balcony overlooking the first floor. Directly behind you,

at your eye level, is an ornate lamp attached to the balcony wall. The base of the

lamp, which is attached to the wall, is gilded in gold. Straight ahead of you, mounted

on a nearby wall beyond the balcony, you see a large bronze plaque dedicated to

the architect who designed the theatre. A simple likeness of the architect, as well as

a few sentences about him, are raised slightly against the bronze background. Sitting

on the shelf directly to your right is a beautiful bouquet of flowers. You see that the

arrangement is largely composed of red roses and white carnations. Looking up,

you see that a large loudspeaker is mounted to the theatre’s ceiling about 20 feet

directly above you. From its orientation, you suppose that it is a private speaker for

the patrons who sit in this balcony. Leaning over the balcony’s railing and looking

down, you see that a marble sculpture stands on the first floor directly below you.

As you peer down toward it, you see that it is a young man and wonder whether it

is a reproduction of Michelangelo’s David.

Psychology: General.

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Figure 4.19 shows the times required for participants

to make their judgments in the various directions.

Participants made the above-below judgments

fastest and the right-left judgments slowest. Franklin

and Tversky point out that such results make sense if

we assume that participants are constructing a spatial

framework while reading the description. Both the

up-down vertical axis and the front-back horizontal

axis are relevant when we navigate in the real world. In

contrast, we suffer many left-right confusions because

of the bilateral symmetries of the body.We have similar

confusions about left and right in our imagery.

In another experiment, H. A. Taylor and Tversky

(1992) compared the relative effectiveness of three

types of spatial information: route descriptions,

survey descriptions, and actual maps. The route

descriptions were a mental tour through the environment,

whereas the survey descriptions gave a bird’seye

view of the environment. After studying the descriptions or the actual map,

participants had to verify route or survey statements about the environment.

A route statement might be

Driving from the Town Hall to the gas station, you pass Maple Street on your right.

A survey statement might be

Horseshoe Drive runs along the northern shore of Pigeon Lake.

Participants were asked to judge whether these sentences were true of the environment

they studied. They were equally fast at judging such questions whether

they had studied route descriptions, survey descriptions, or actual maps. From

this result, Taylor and Tversky concluded that people can construct cognitive

maps from verbal descriptions as effectively as from actual maps.

We can convert verbal descriptions into cognitive maps of our environment.

•Conclusions: Visual Perception and Visual Imagery

This chapter has also reviewed some of the evidence that the same brain regions

that are involved in visual perception are also involved in visual imagery. Such

research has presumably put to rest the issue raised at the beginning of the chapter

that the visual imagery experiences are purely epiphenomenal. However,

although it seems clear that perceptual processes are involved in visual imagery,

it remains an open question to what degree the mechanisms of visual imagery

are the same as the mechanisms of visual perception. Evidence for a substantial

overlap comes from neuropsychological patient studies (see Bartolomeo, 2002,

for a review). Many patients who have cortical damage leading to blindness

have corresponding deficits in visual imagery. As Behrmann (2000) notes, the

Conclusions: Visual Perception and Visual Imagery | 113

Response times (s)

2.5

1.5

2.0

1.0

0.5

Ahead Behind Right Left

Direction

Above Below

FIGURE 4.19 Results from

Franklin & Tversky’s experiment

demonstrating that we create

mental images from a word

description of a spatial

structure. Participants read

stories that required them to

orient themselves in an

imaginary environment, then

were asked to identify the

locations of objects in the

environment. The results are the

times required to identify objects

in various directions. (From

Franklin & Tversky, 1990. Reprinted by permission

of Experimental Psychology: General.)

Anderson7e_Chapter_04.qxd 8/20/09 9:43 AM Page 113

correspondences between perception and imagery can be quite striking. For

instance, there are patients who are only unable either to perceive or to image

faces and colors, but are otherwise unimpaired in either perception or imagery.

Nonetheless, there exist cases of patients who suffer perceptual problems but have

intact visual imagery and vice versa. Behrmann argues that visual perception and

visual imagery are best understood as two processes that overlap but are not identical,

as illustrated in Figure 4.20. To perceive a kangaroo requires low-level visual

information processing that is not required for visual imagery. Similarly, to form

a mental image of a kangaroo requires generation processes that are not required

by perception. Behrmann suggests that patients who suffer only perceptual losses

have damage to the low-level part of this system, and patients who only suffer

imagery losses have damage to the high-level part of this system.

114 | Mental Imagery

Low-level

visual analysis

High-level

generation

Intermediate

visual

processing

Perception Imagery

FIGURE 4.20 A representation

of the overlap in the processing

involved in visual perception and

visual imagery.

1. It has been hypothesized that our perceptual system

regularly uses mental rotation to recognize objects in

nonstandard orientations. In Chapter 2 we contrasted

template and feature models for object recognition.

Would mental rotation be more important to a template

or feature model?

2. Consider the following problem:

Imagine a wire-frame cube resting on a tabletop with

the front face directly in front of you and perpendicular

to your line of sight. Imagine the long diagonal that

goes from the bottom, front, left-hand corner to the

top, back, right-hand one. Now imagine that the cube is

reoriented so that this diagonal is vertical and the cube

is resting on one corner. Place one fingertip about a

foot above the tabletop and let this mark the position of

the top corner on the diagonal. The corner on which

the cube is resting is on the tabletop, vertically below

your fingertip.With your other hand, point to the

spatial locations of the other corners of the cube.

Hinton (1979) reports that almost no one is able to performthis

task successfully. In light of the successes we have

reviewed for mental imagery,why is this task so hard?

3. The chapter reviewed the evidence that many different

regions are activated in mental imagery tasks—parietal

and motor areas in mental rotation, temporal regions

in judgments of object attributes, and hippocampal

regions in reasoning about navigation.Why would

mental imagery involve so many regions?

4. Consider the map distortions such as the tendency to

believe San Diego is west of Reno. Are these distortions

in an egocentric representation, an allocentric representation,

or something else?

Questions for Thought

Key Terms

allocentric representation

cognitive maps

egocentric representation

epiphenomenon

fusiform face area

mental imagery

mental rotation

parahippocampal

place area

route maps

survey maps