COLORED HEARING, or CuRoALESTIIESIA. The anomalous association of colors with sounds. It is the commonest type of symesthesia, or the formation of unusual connections between sen sations of different sense departments. While colored hearing is relatively frequent (statis tics record one person in eight), it is exhib ited in very varied forms. These may, however, be grouped, in the first place with regard to the nature and intensity of the photism (the color which is induced), and secondly with re gard to the nature of the inducing sound. The induced color may, in rare cases (see works of Gruber and Whipple, indicated in the bibliog raphy at the end of this article), be of hallucina tory intensity, so as to be seen objectively when the eyes are open. Usually the intensity is less—the photism is localized (Flournoy), though not projected. In the third grade the photism is 'imagined'—the color is really pres ent as a visual sensation, but has no definite place; e.g. all soprano voices may be white, all tenor voices green. Fourthly, photisms may be simply 'thought,' no visual sensation being pres ent. Finally, certain persons possess 'negative photisms'—they cannot say what color a sound has, but can say what colors it 'ought not' to have. Any auditory impression may serve as the inducing agency. The sources may, therefore, be grouped, for convenience, as (1) musical tones and noises (subdivided into single notes, chords and discords, musical selections. etc., each with further arrangement according to pitch, intensity, clang-tint of instrument), and (2) articulate speech (vowels, consonants, words, sentences).
Can we find any uniform relation between these two series of variables, the inducing sound and the induced color ? Certain investigators, the questiouary method, have answered in the affirmative. Thus, Bleuler and Lehmann that "sharply demarcated, small, bright, or pointed photisms are aroused by high-pitched sounds. Red, yellow, and brown are frequent
colors: violet and green are rare; blue stands midway in frequency. The tendency to second ary sensations is inheritable." Other investigators (e.g. Whipple), who have made detailed experimental studies of a few individuals, contend that the questionary method is inadequate, and that there is a considerable degree of variation, not only between individuals, hut also for the same individual at different times, so that "generalization is at present to be avoided." The explanation of colored hearing is usually found in the persistence in adult life of certain curious and useless connections 'between sensa tions. Childhood is characterized by the forma tion of countless mental combinations. Of these, only the useful or meaningful normally sur vive. The persistence or recrudescence in the mature individual of anomalous though not ab normal auditory-visual connections is the con dition of chronhesthesia. The association may be direct (habitual or specific connection of .sensations) or indirect (connections of sensa tions through the organic complex embodied in a feeling). The absence of abnormality is at tested by the facts that colored hearing is no more frequent among neurotic than among nor mal individuals, and that the associations do not interfere with mental operations. They may, indeed, furnish positive sources of pleasure to their possessor.
Consult: Bleuler and Lehmann, Zirangstniis sige Liehtcmyfindun,p (lurch &hall (Leipzig, 1881) ; Flournoy, Les dr synopsic (Paris, 1893) : G. M. Whipple, American Jour nal of Psychology, vol. vi. (Worcester, 1900) ; Gruber, L'audition colorec et les phawinenes similaires (Paris, 1S92).