Boris Sidis

“ I use the term vividness in the sense of clearness and distinctness and not in the sense of intensity as it is often used; even those psychologists who do not use intensity and vividness indiscriminately ascribe both of them equally to sensation and image.
Vividness and intensity are understood by me to be two fundamentally qualitatively different aspects, or attributes. Sensations have intensity, but no vividness; images or representations have vividness, but no intensity. Sensory elements may vary from minimum to maximum intensity. ”

“ Strong stimulations may give rise to sensations of great intensity, but the vividness of the representative elements may fall so low as almost to reach the minimum. When the vividness is so low as to reach the minimum, the representative elements cannot be used as substitutes and, since reproduction belongs to representative elements which symbolically reproduce the sensations by the process of substitution, reproduction or memory of the original experience is absent and there is a break, a gap in mental continuity, dissociation results. ”

“ The depths and extent of dissociation of mental systems may be regarded as variables of vividness. Dissociation varies inversely as vividness. When vividness is at its minimum, dissociation is at its maximum. The phenomena of functional psychosis having their origin in states of dissociation may thus be regarded psychologically as functions of vividness, the most characteristic attribute of representative elements. ”