------------------------------------------------------------------------ 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.