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In addition to thinking in the form of statements, a person can also think in the form of images, especially visual images.
Many of us feel that part of our thinking is done visually. It often seems that we reproduce past perceptions or fragments of them and then operate on them as if they were real percepts. To appreciate this moment, try to answer the following three questions:
- What shape are the ears of a German Shepherd?
- What letter will you get if you rotate the capital N 90 degrees?
- How many windows do your parents have in their living room?
In answer to the first question, most people say they form a visual image of a German Shepherd’s head and «look» at the ears to determine their shape. When answering the second question, people report that they first form an image of a capital N, then mentally «rotate» it 90 degrees and «look» at it to determine what happened. And when answering the third question, people say that they imagine a room and then «scan» this image by counting the windows (Kosslyn, 1983; Shepard & Cooper, 1982).
The above examples are based on subjective impressions, but they and other evidence indicate that the same representations and processes are involved in images as in perception (Finke, 1985). The images of objects and spatial areas contain visual details: we see a German shepherd, capital N or the living room of our parents «in our mind’s eye». In addition, the mental operations that we perform with these images are apparently similar to the operations performed with real visual objects: we scan the image of the parents’ room in much the same way as we would scan a real room, and we rotate the image of the capital N in the same way as we rotated would be a real object.
The nervous basis of images
Perhaps the most compelling evidence for the similarity of images with perception would be that both are mediated by the same brain structures. In recent years, a lot of this kind of data has been collected.
Some of this data comes from studies of brain-damaged patients and shows that all visual disturbances in a patient are usually accompanied by similar visual disturbances (see eg Farah et al., 1988). A particularly striking example is provided by patients with damage to the parietal lobe of the right hemisphere, who as a result develop visual neglect of the left side of the visual field. Although not blind, these patients ignore everything on the left side of their visual field. A male patient may, for example, not shave the left side of his face. This visual ignorance extends to images, as the Italian neurologist Bisiach has established (see, for example, Bisiach & Luzzatti, 1978). Bisiac asked his patients with visual ignorance to imagine a familiar square in their native Milan: what it looked like when facing a church. These patients named most of the objects to their right, but very few of those to their left. When asked to imagine the scene from the opposite perspective, as if they were standing in front of a church and looking at the square, the patient was ignored by the objects they had previously named (these objects were now on the left side of the image). So, in these patients, the same ignorance was manifested in images as in perception, from which it can be concluded that damaged brain structures in them usually mediate both images and perception.
Some recent brain-scanning studies have shown that, in normal subjects, areas of the brain associated with perception are also associated with imagery. In one experiment, subjects performed both a mental arithmetic task (“Start at 50 and count by 3”) and a visual image task (“Imagine walking around your neighborhood, turning right and left alternately, starting from your door”). During the performance of each task by the subjects, blood flow was measured in different parts of the cortex. Blood flow in the visual cortex was greater when the subjects completed the image task than when they performed the mental arithmetic task. In addition, the pattern of blood flow intensity in the image task was similar to that commonly found in perceptual tasks (Roland & Friberg, 1985).
A recent PET scanner experiment (Kosslyn et al., 1993) provides a striking comparison of brain structures involved in perception and imagery. During the brain scan, the subjects performed two different tasks, a perceptual task and an imagery task. In the perception task, a rectangular capital letter was presented against the background of a grid, and then a cross was presented in one of the cells of the grid; the subject’s task was to decide as quickly as possible whether the cross fell on any part of the rectangular letter (Fig. 9.8). In the task, the images were again presented with a background grid, but without a rectangular letter. Below the grid was a lowercase letter, and the subjects were previously instructed to create an image of an uppercase version of that lowercase letter and project it onto the grid. Then a cross was presented in one of the cells of the grid, and the subjects had to determine whether it fell on any part of an imaginary rectangular letter (Fig. 9.8). Not surprisingly, the perceptual task caused an increase in neural activity in regions of the visual cortex. But the same thing happened in the image problem. Indeed, the image task led to an increase in activity in those brain structures that, as far as is known, belong to the primary cortical areas that are the first to receive visual information.
Therefore, images are similar to perception, starting from the earliest stages of information processing in the cortex. In addition, when neural activation in the two tasks was directly compared, activation was greater in the imagery task than in the perceptual task, suggesting that the imagery task required more «perceptual work» than the perceptual task. These results leave little doubt that imagery and perception are mediated by the same neural mechanisms. And here again we find in the results of biological studies confirmation of the hypothesis that was originally proposed for the psychological level.
Operations on images
As we noted, mental operations on images are performed similarly to operations with real visual objects. Numerous experiments objectively confirm these subjective impressions.
One of the most well-studied operations is mental rotation. In a classic experiment, subjects were shown a capital letter «R» in each trial. This letter was presented both normally (R) and mirrored (R), as well as with the usual vertical orientation or rotated to various angles (Fig. 9.9). The subjects had to decide whether the letter was normal or mirrored. The more the letter was rotated relative to its vertical position, the longer it took the subjects to make a decision (Fig. 9.10). These results suggest that when making a decision, the subjects mentally rotated the image of the letter until it became vertical, and then checked whether it was a regular letter or a mirror image.
Rice. 9.9. The study of mental rotation. Examples of letters presented to the subjects in the study of mental rotation are shown. After each presentation, the subjects had to decide whether the letter was normal or mirrored. The numbers show the angle of rotation relative to the vertical (according to: Cooper & Shepard, 1973).
Rice. 9.10. Decision time in the study of mental rotation. The time taken to decide whether a letter was normal or mirrored was greatest when the letter was rotated 180°, i.e., when it was presented upside down (after: Cooper & Shepard, 1973).
Another operation equally applicable to images and perception is the scanning of an object or space. In the image scanning experiment, subjects first studied a map of a non-existent island containing 7 special areas. The card was removed and the subjects were asked to imagine its image and focus on a certain place (for example, a tree in the southern part of the island — Fig. 9.11). The experimenter then named another location (for example, a tree at the northern end of the island). The subjects had to, starting from a fixed place, scan their image of the island, find the named place, and then press the “arrive” button. The greater the distance between the starting point and the named place, the longer it took the subjects to answer. This indicates that the subjects scanned their image in much the same way as they would scan a real object.
Another similarity between image processing and perceptual processing is that both are limited by the amount of grain. For example, the size of the graininess of the electronic device and the TV depends on how small the details on the screen can be in order to remain distinguishable. Although the brain does not actually have a screen, one can imagine that the images appear as if in a mental environment, the graininess of which limits the amount of detail that can be found in the image. If the grain size is fixed, then smaller images are more difficult to see than large ones. This position is confirmed by many data. In one experiment, subjects first formed an image of a familiar animal, say a cat. They were then asked to decide if the animal they imagined had a particular property. The subjects made quicker decisions when the feature was large, such as a head, than when it was small, such as claws. In another study, subjects were asked to imagine an animal of various relative sizes—small, medium, or large. They were then asked to decide if it had a particular property. The subjects made quicker decisions when the feature was large, such as a head, than when it was small, such as claws. In another study, subjects were asked to imagine an animal of various relative sizes—small, medium, or large. They were then asked to decide if it had a particular property.
In the case of large images, the subjects made decisions faster than in the case of smaller ones. So, both in images and in perception, the larger the image, the easier it is to see the details of the object (Kosslyn, 1980).
visual creativity
There are countless stories of scientists and artists creating their most outstanding work through visual thinking (Shepard & Cooper, 1982). While these stories are not rigorous evidence, they are one of the best indicators of the power of visual thinking available. Surprisingly, visual thinking works very effectively in such abstract areas as mathematics and physics. Albert Einstein, for example, said that he rarely thinks in words and develops his ideas in the form of «more or less clear images that can be ‘arbitrarily’ reproduced and combined.» So, Einstein said that the idea of the theory of relativity came to him initially when he thought about what he “saw”, imagining how he catches up with a light beam and equals it.
Perhaps the most remarkable example comes from chemistry. Friedrich Kekule von Stradonitz tried to determine the molecular structure of benzene (which turned out to be ring-shaped). One night he dreamed that the writhing, serpentine figure suddenly coiled itself into a closed loop, biting its own tail. The structure of this snake turned out to be the structure of benzene. The image in the dream turned out to be the solution to the most important scientific problem.
Thinking in Action: Problem Solving
For many people, problem solving represents thinking itself. When solving problems, we strive for the goal, not having a ready means to achieve it. We have to break down the goal into sub-goals, and perhaps divide these sub-goals further into even smaller sub-goals until we reach a level where we have the necessary means (Anderson, 1990). See →