Everyone knows what it is like to close one's eyes and call up a visual image using the "mind's eye." For most people this image is usually fleeting and undetailed, but for those who possess an ability for eidetic imagery, this image is like a tangible picture that can be manipulated and seen in great detail.
Eidetic imagery is a psychological puzzle that has multiple definitions, an extensive history, and a long list of characteristics. The exact relationship between eidetic imagery and other kinds of visual imagery is not quite understood, and comparisons between the two have left many psychologists divided on opposite sides of the issue.
There have been many experiments over the years to determine who is eidetic and who is not, and much of this research has turned up an odd correlation between eidetic imagery and age.
Eidetic imagery is a unique phenomenon that has baffled psychologists for decades, but the interesting things that it can tell us about visual stimulation and cognitive abilities will continue to perpetuate further research for decades to come. Much of the early systematic research was done in Germany between 1910 and 1930, and important works such as those by F.R. Jaensch were later translated into English and reviewed by psychologists such as Allport and Kluver. However, the interest in this subject faltered between 1930 and 1960. Fewer than ten studies were reported, not including "several clinical reports of patients with vivid imagery that was quite unrelated to any preceding information."
In recent years, however, the issue has gained a new vested interest, due largely to the highly recognized work of Ralph N. Haber. Other researchers who have contributed to this renewed interest have included Richardson's recent review of eidetic research and Norman's "contemporary theoretician's skeptical point of view." Therefore, most of the strides in understanding eidetic imagery have happened in the last thirty years and are continuing to happen today.
There are several characteristics of eidetic imagery that, while not necessarily distinguishing it from other forms of visual imagery do provide insight into what eidetic images are like. According to Haber and Haber, "the most important characteristic is negative: Eidetic imagery is not photographic." The myth that eidetic images are exact copies of the stimulus is an old one, and this accuracy criterion was often used as an identifier of EI. However, eidetic images are not formed as a photograph is formed, but instead are constructive, not reproductive. Eidetic images can be highly detailed or sketchy and fragmentary, and are often no more accurate than a normal memorized image. Therefore, using accuracy as a criterion for EI is unsubstantiated.
It takes time for an eidetic image to form. An eidetiker generally has to look at the stimulus for at least three to five seconds and to inspect each part of the stimulus for enough time. Once the EI has been formed, the subject is able to report their image as though they were actually looking at what they were describing, very fluently and confidently. Noneidetikers would verbalize their images very hesitantly, as if searching for an imperfectly organized and stored memory.
Eidetic children do not just see eidetic images from only one kind of stimulus, but instead can construct them from all kinds of stimuli. Also, most EI last for more than half a minute, with the average being well over several minutes.
It is also possible to keep eidetic images from forming. Many children use techniques such as naming each item they are looking at so that an EI will not develop. Apparently, actively using verbal rehearsal interrupts the eidetic process and keeps an image from forming. This explains why eidetikers have a difficult time creating images of printed text; they tend to read the text as they look at it and this interrupts the EI process.
Almost all eidetikers say that they can terminate their images by simply blinking their eyes, looking away, or shifting their eyes to a new object. Also, almost all report the same pattern of fading for their images. This is due partly to visual factors such as loss of clarity, color, contrast, etc., and partly to verbal descriptive limitations. Only one child has ever claimed that she could make an image last as long as she wanted it to, and only then by concentrating on the image. Otherwise, her images would fade as normal. Therefore, the way in which an image fades is a very important characteristic of eidetic imagery.
Other eidetic characteristics include projecting images onto the surfaces that contain the stimulus, moving images around on a surface without leaving the boundaries of the surface, combining two images together into a composite image, and seeing an image in one eye when they look at the stimulus with only one eye. All of these characteristics help to identify eidetic imagery and to clarify what it is eidetikers experience when they form an eidetic image.
When defining what visual imagery is, it is often important to figure out what it is not. One way to do this is to compare visual imagery with visual perception, visual hallucinations, and nonvisual memory.
Visual imagery is different from visual perception because visual perception requires the object to be actually present and visual imagery does not. For example, when one says, "I see a rock," and there is in fact a rock in sight, then that is a visual perception. If there were not a rock in sight, that would be a visual image.
However, if one thought there was a rock actually present when in truth there was not, that would be a visual hallucination. In a third case, if one refers to the memory of the rock using some other kind of memory device such as verbal, abstract, propositional, etc., then that would be a nonvisual memory and not a visual image.
Therefore, visual imagery concerns seeing in one's mind an object as if it were right there, when in fact it is not.
Much of the debate about eidetic imagery stems from the question about how separate eidetic imagery truly is from conventional visual imagery. Many believe that they are two qualitatively distinct abilities because of the "important phenomenological differences [which] accompany them and that, presumably, different sets of internal processes produce them. This view...treats eidetic imagery as unique and intimately related to the 'raw' processes of perception; visual memory imagery is usually carried along as rather uninteresting baggage" (Gray and Gummerman, 399).
Others tend to think that eidetic imagery is simply another kind of visual imagery or that it differs only in its "uncommon vividness or clarity" (Gray and Gunnerman, 399). Haber (237) takes the stance that eidetic imagery is "a particular kind of visual imagery, one quite rare. Visual imagery in general, while having the quality of being seen, usually does not have the quality of being akin to looking at the stimulus itself. When it has that latter quality, then it is eidetic. The perceptlike character of the image distinguishes eidetic imagery from other kinds of visual imagery." Another way that eidetic imagery is different from visual imagery is that EI does not seem to be completely under the eidetikers control but rather is influenced or determined by the specific viewing conditions. There are tests, however, which are able to powerfully distinguish eidetic imagery from other kinds of visual imagery. It is the extreme clarity of the eidetic image that differentiates it from the normal visual image, but at this point it is still unclear as to how different the two really are.
"Eidetic images do differ from visual imagery in general in that they do not seem to be under complete voluntary control but are determined or influenced by the actual viewing conditions." Therefore, these six tests are used to differentiate eidetic imagery from other kinds of visual imagery:
. Whether an image of a particular part of a stimulus appears or not depends on whether that part has just been visually examined;
. Whether that image of a part appears depends on whether that part has been visually examined by the eye that is currently open;
. Whether a part remains visible in the image depends on whether it has yet faded, something that cannot be prevented by the subject;
. Whether a part remains visible depends on whether there is a projection surface against which to see it;
. Whether an image remains visible requires the subject to inhibit eye blinks;
. Whether an image remains coherent depends on whether subsequent images are present that superimpose and combine together.
Since 1964, nearly all of the experiments on eidetic imagery have followed the same procedure. It was established by Haber and Haber and is usually performed on large groups of elementary school children. The experiment begins with placing a brightly colored square patch on an easel or other neutral surface. The subject stares at this square for ten seconds and then the square is taken away. The experimenter then asks the subject questions about what they see on the easel now that the square is gone to determine afterimages and to familiarize the subject with the procedure.
Once this has been done with all four squares, the experimenter moves on to detailed pictures. The instructions for this stage are slightly different. The subject is given thirty seconds to look at the picture and is told to move his or her eyes around in order to study all of the details of the picture. Once the picture is taken away, the subject is encouraged to continue moving their eyes around as they describe what they see. This process is repeated for four different pictures and can take anywhere from five to thirty minutes. While there are variations on this procedure, this is the basic outline of how to test for eidetic imagery.
All of the research over the years has shown a definite correlation between eidetic imagery and age. EI tends to appear in children much more frequently than in adults and many recent researchers have been trying to understand this supposedly negative correlation. However, the experiments they have been conducting have not supported the assumption that only children can be eidetikers. For example, Leask et al. did a long-term study on twelve eidetic children and found that eleven of them were still just as eidetic as they had been at the beginning of the study. Also, there seems to be no more of a concentration of eidetikers in younger children than in older children.
One theory to explain this discrepancy is that children are much more visual creatures and this preference makes it easier for them to use their eidetic abilities. Adults, however, are more reliant on verbal encoding, and this, as was discussed before, interrupts the eidetic process. Unfortunately, this theory has not been well tested, and so it is still unclear as to why the correlation between age and eidetic imagery exists.
"S", the famous subject of A.R. Luria, is known throughout the world for his incredible memorial powers. He used his synesthetic capabilities to remember long strings of words and syllables and had unlimited capacities. Part of his technique involved intense visual imagery where words or sounds actually had visual equivalents in his head.
Due to this powerful visual imaging, he is often referred to as an eidetiker. However, "S" usually "used vivid 'imagination imagery' that did not reproduce preceding stimulation at all" (Gray and Gummerman, 402). For instance, "S" would take each word that he was memorizing and place it in a particular location on his mental "street," thereby locking it in his memory. Afterwards, all he had to do to reproduce the string of words was to walk back down that "street" and "see" where each word was placed.
This differs from eidetic imagery because he did not reproduce the actual image in his mind and reproduce that; instead, he made his own images that corresponded with his synesthetic sensitivities. Therefore, while "S" did have amazing visual capabilities, he was not using eidetic imagery.
The vast majority of the research on eidetic imagery to date has been done on children in the pre-pubescent years since this is the age when an affinity for eidetic abilities is most prevalent. The most famous exception to this rule is a woman named "Elizabeth," who was studied and written about by Charles F. Stromeyer in 1970. She was an artist and teacher at Harvard who could mentally project detailed and exact images onto her canvas and was even able to move her eyes about to inspect the image while the image stayed still. She could also reproduce poems in a foreign language years after having seen the original printed page.
In Stromeyer's tests on her abilities, "Elizabeth" was presented with a 10,000-dot stereogram pattern to one eye for a specified length of time and then was asked to superimpose her eidetic image onto another pattern presented to her other eye. She was able to perform this task with great ease and could see depth and figures in these patterns. Non-eidetikers need a stereoscope to perform this feat.
"Elizabeth" was also capable of projecting her eidetic images onto other images, often obscuring the actual image. Her eidetic images were capable of after-images and movement after-effects just like that of actual visual stimulus, and she is even reported to have been able to see a 10-second section of a movie in complete eidetic detail.
Her only constraint was that she had to move her eyes to scan an eidetic image and generally would create the image in sections rather than as a whole. Also, "Elizabeth’s images did not just fade, but instead would dim and break apart piece by piece. In any case, "Elizabeth" is the only one of her kind. Since the publication of Stromeyer's paper, no other adult eidetiker of her caliber has been found.
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