CHAPTER XI
Gustatory Imagination and Memory
The Nature and Frequency of Mental Images
It is a familiar fact that in one way or another and in different degrees to different individuals it is possible to have sensory experiences without the actual presence of their accustomed stimuli. Thus, many people can recall “in their mind’s eye” the colors of objects, their shape and structure, when they are no longer in the presence of the object thought of. Or, “in their mind’s ear,” they can hear the blare of a trumpet, the voice of a friend, the hissing of steam, when no corresponding stimulus is present to the ear. Similarly, “in imagination” many can experience the tactual feel of velvet, the odor of onions, the warmth of sunshine, the ache of a tooth, the nausea of seasickness.
“Thus, I can call up in my mind’s eye, more or less vividly, my boyhood home, and seem to see, though more obscurely than if I were present on the spot, the house and barn, the grape arbor, the garden, even my little bookcase in the library. I can smell the honey in the bee boxes, and can hear the general hum and stir of the hive. I can do this because I can call up images of these past experiences. Or, by putting together the images of wheels, sails, birds, and ropes which I have actually seen I can create in my mind’s eye an aeroplane of a pattern which has never yet been constructed.” This constructive performance would constitute “imagination” as distinguished from mere “imagery.”
These images of imagination are not to be confused with the after sensations which we have already described. They may be experienced days, or even years, after the first application of the original stimulus. Nevertheless, these “mental images,” or “centrally excited sensations,” are described as essentially sensory in character—they have the attributes of all sensory experiences, such as intensity, extensity, duration, clearness, locality, quality, and modality. In fact observers have been found for whom these mental images were so realistically sensory that actual negative after sensations, in the case of visual images, have been reported as following upon them.
In the case of many individuals, these experiences of objects in their absence are relatively rare and obscure, and in some cases, indeed, are so obscure as to lead the individual to deny the existence of such experiences. In still other cases the centrally excited sensations, the mental images, are experienced in their vivid and, apparently, immediately sensory form only under special conditions, as in dreams, hallucinations, drowsiness, or fatigue, or under the influence of special drugs. It has appeared from the study of mental images that, in so far as they are present, they are not equally reported in the different modes of sensation. Visual images in some cases, auditory images in other cases, and motor images in still others, have seemed to be so specially frequent, vivid, or easily aroused that at one time it was customary to classify individuals on the basis of their images as visuelles, audiles, motiles, and efforts have even been made to adapt a method of teaching to the presumed “imagery type” of the student. In the present connection our interest is only in inquiring whether and in what degree “images of taste” are present.
Mental Images of Taste
Is there a “gustatory” or taste imagination as well as a visual or an auditory imagination? It should, of course, be borne in mind that tastes may be “thought of,” “referred to,” or “indicated” without there actually being taste qualities present in experience. Thus, I may refer to the “saltiness of the pork” and discuss it in detail without having in consciousness the sensory tang and quality of “salt.” The saltiness may be “represented” in my thinking in this case, not by a taste quality at all, but by the word which stands for such a quality, or even by a visual picture of a white granular substance, or an elongated strip of meat. Only if the immediate and unanalyzable experience of sensory “salt” is present is there evidence, in this case, of an “image of taste.”
Obviously, we must mainly rely in such cases on the testimony of the observer, although there have been investigations made of a more objective sort, in which it is shown that the reported “images” are so similar in character to actual sense experiences that the observer, under appropriate conditions, cannot distinguish between the two.