An Introduction to Pictorialism
We can introduce the pictorialist approach by posing some well-selected questions that have appeared in pictorialist literature.
Chances are that you made use of a mental image to answer at least one of these questions.
Inspired by such examples, some experimental psychologists began to question the supposition that thinking processes could be reduced to propositional or descriptive form. There has been a substantial amount of literature in both psychology and philosophy, particularly in this century, that
LINKS THOUGHT EXCLUSIVELY WITH LANGUAGE.
Using one of the examples, we can question this supposition this way
Do we think that a German Shepard's ears are "pointed" or "triangular" because we believe the PROPOSITION
A German shepard's ears are pointed,
OR is it because
HAVING A MENTAL IMAGE of a German Shepard's ears
enables us to describe their shape as "pointed"?
There is a substantial difference between the two cases. In the first, the sentence or proposition itself expresses the content of our belief. The belief is represented in a form that is immediate, direct, and self-contained. In the second, the belief we have about the shape of the ears is derivative or indirect. The mental image is used as the BASIS for a further description. The image itself does not express the belief. A further step is required -- INTERPRETING THE IMAGE -- before it is possible to express a belief in linguistic form.
Phenomenologically, it seems to most people that interpreting a mental image is something they really do. If this is the case, pictorialists argue, then there is a distinctive form of information storage in the mind that is in which we have information represented VISUALLY or PICTORIALLY rather than LINQUISTICALLY.
Consider another example. Study the figure below for a moment.
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Now, without looking at the figure, determine how many corners are formed by the outline of the figure.
People who can perform this cognitive task will generally explain that they have examined a mental image of the figure and simply counted the corners. In this case, a simple perception seems to be stored and then recalled in a pictorial format. How could we explain this phenomenon of information storage and retrieval in terms of stored and retrieved descriptive knowledge? There does not seem to be any obvious way.
The above considerations allow us to start developing the case for pictorialism. Such examples make plausible the claim that we store information in the form of images and recall them as images. When we recall them, we are able to derive additional information from the image that was not explicitly encoded at the time the original perception was stored. Propositions can be derived from the image, which is a unified, analogue (non-discrete) form of information storage. Since information that was not explicitly stored can be derived from the image, the image exhibits emergent properties.
In contrast, the descriptivist argues that the image has nothing to do with the recollection of the information. The information is stored in a propositional format, and when it is recalled the image is just an epiphenomenon which non-functionally mediates the formation of descriptional propositions that form the actual content of our recollection.
The case for the pictorialist side can be devided into support derived from the following categories.
1. Logical/Introspective Support for Pictorialism
Visual information can give rise to an
INFINITE NUMBER OF POSSIBLE DESCRIPTIONS.
This fact creates a problem for a descriptivist account of visual memeory.
Recall a picturesque scene. A valley, seaside, or moutainscape. Describe the scene.
What is the basis for the description?
If our memory of such scenes is based on DESCRIPTIONS as they were originally stored, which descriptions would be selected for storing this visual information? Would I store various random descriptions as they occur to me while I survey the scene? Or would I carefully choose the most accurate and precise descriptions I could think of ?
The problem is that as I look upon a complex scene, any number of descriptions might be accurate and equally appropriate:
Would I then remember ALL these descriptions? Potentially, there is an infinite number of them.
And what of the mental image as it appears to me? What accounts for the experience of "reading off" -- or interpreting -- the image and forming a description based on that?
Consider another example: If you succeeded in the "F" experiment, how was it possible unless the entire appearance of the figure was remembered? Most people do not consciously think to count the corners when they are simply told to look at the figure -- yet most people can easily perform the task of mentally recalling the figure and counting the corners.
How can the descriptivist explain these ordinary feats of human memory? One possible solution is that we unconsciously record descriptive information of the appropriate type. There is no conscious selection of appropriate sentences or descriptive phrases. Rather, something deeper and more abstract than ordingary sentences do the work of storing information. This suggestion has some plausiblity. But still, the question remains: Does the mind anticipate dozens, hundreds, or thousands of possible future descriptions? How many unconscious "descriptions" are necessary to perform the work of memory? Again, since one can argue that there are potentially an infinite number of such descriptions, and since we do apparently read off or interpret a mental image, it seems to be a reasonable claim that the images themselves rather than some large set of (unconsciously selected) descriptions are responsible for memory.
Hence, pictorialists may argue, it appears that the descriptivist is committed to supposing that the number of descriptions stored for a single memory is either
Therefore, the pictorialist reasons, it is best to simply accept the introspective evidence we have as a starting place: we have no conscious awareness of storing and recalling descriptions when we store and recall visual images. Rather, we seem to store and recall images (or, as imagists sometimes put it, inner representations with the properties of images -- see experimental evidence, below).
2. Evolutionary Support for Pictorialism
From the evolutionary standpoint, it would be more efficient to store visual information in a "pictorial" format than a descriptive format. The pictorial format provides more versatility -- more options for the use of information by the organism. If what is recalled is more like a picture than a description, a conscious organism has the option of deriving specific (propositional) information from holistic (visual, non- propositional) information. A hunter who remembers a visual image of a path through the woods, rather than sequence of right and left turns, has the option of taking short cut. Such versatility in information retrieval would have distinct evolutionary advantages.
3. Physiological Support for Pictorialism
Brain studies show a close association between visual centers and the process of visual imagination. When mental images are reported, the visual centers of the brain are activated. If the visual centers are destroyed, the ability to form descriptions based on visual memories is impaired. One famous case reports of a man who lost vision on the left side of the visual field. When asked to describe the village square that he knew very well since childhood, he could only describe the shops and objects on the right-hand side of the square. The descriptive knowledge was not lost, however, because the man could recall the other side of the square by imagining himself standing in a different location. This case argues that images are prior to and necessary for description of certain memories.
4. Experimental Support for Pictorialism
The pictorialist position is supported by a substantial body of evidence in empirical psychology. Among the most important investigators are Kosslyn (1980, 1983, 1994), Sheppard and Metzler (1971), and Finke (1985).
A large class of experiments fall into the category of
TIMED RESPONSE EXPERIMENTS.
These provide a substantial part, but not all, of the empirical, experimental support for pictorialism.
These experiments typically adhere to the following general format: The subject is given some problem or task involving a minimal ability in visual memory. The time to perform the task is measured. Averaging the times over many trials and over different subjects is presumed to cancel anomalous data and and false reports. The properties of the mental representations are postulated on the basis of times.
SHEPARD AND METZLER
Shepard and Metzler's 1971 experiment is the most famous of this type.
Subjects were shown line drawings of two simple three-dimensional shapes. Subjects were instructed to find if the figures were congruent on non-congruent (the "same" or "different"). In half the cases the shapes were identical except for a rotation in space. The shapes were rotated with respect to each other either in depth or in the picture plane. In the remaining half, the shapes were mirror images and could not be brought into coincidence through any possible rotation.
Eight male subjects were shown 1600 pairs of shapes. Each subject was tested in several test sessions of about one hour, for a total time of 8-10 hours. The reaction times for each subject to perform the task (in the case of matching pairs only) were averaged.
It was discovered that the average time it took subjects to identify which shapes were identical was directly proportional to their angular displacement from each other (approximately 50 degrees per second). The difference in times for figures rotated in the picture plane instead of in depth was negligible.
From this finding it was postulated that some functional module in the mind performs a holistic rotation on mental images at a fixed rate of approximately 50 degrees per second. When the rotated mental image was brought into coincidence with the perceived figure, the subject would judge that the images were identical. The hypothesis of functional rotation was found to match the subjects' subjective experience that they mentally rotated the images.
The importance of the Shepard and Metzler experiment is that it
(1) Paved the way for the idea that certain problems needed mental images to be solved, and that the use of these mental images could have empirical indicators. This led to the idea that images were not to be banned from empirical psychology after all.
(2) Apparently showed that the rotation of metal images occurred both holistically and mechanically. This indicated that holistically (non-propositonally) processed images might be irreducible elements in the computational processes performed by the brain. Since the mental images involved in their experiment appeared to be rotated at a (mechanical) fixed rate, this indicated a specific brain structure and/or computational process could be responsible for executing mental rotations. Thus, there appeared to be a specific mental function instantiated in a specific brain mechanism; in other words, a primitive mental operation appeared to be discovered. This led to the idea that analog processes could be part of reductive cognitive psychology.
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