Boris Sidis

“ The hardness, the smoothness, the bodily resistance are perceived by the visual sense and are visual, but as such they, of course, differ from the sensations experienced by their appropriate sense organs, as when for instance the same sensations are given by touch or by muscular and kinesthetic sensations. Those muscular and tacto-motor sensations appearing as visual are not memory-images, but they are actual sensations, they are secondary sensations; they are secondary sensory elements which give the fullness of content to the percept, having visual sensory elements as its nucleus. ”

“ A sensation has intensity, an image totally lacks it. (b) An image is a reproduction or rather a representation, a symbol of a sensation, but no sensation represents another; a sensation, unlike an image, is not mediate, but immediate experience. (c) A sensation bears the mark of externality, an image lacks it. Finally (d) a sensation cannot be called up at will, while an image is independent of peripheral stimulations of external objects and is usually under the control of the will. No sensation differs so much from another as the image differs from its corresponding sensation. ”

“ Sensory elements and their synthesis, the percept, have motor tendencies, while the image or idea has not any motor tendencies. The reason why every image and idea has been made ideo-motor is because images or representations have been regarded as sensory in character, as weakened sensations, as 'sensationalettes' so to say. Bergson clearly sees the qualitative difference of the two; he insists on the non-motor character of the image in contradistinction to the strongly motor character of the sensation and the percept. ”

“ To refer as Külpe does to a hallucination as an intensified image is to reason in a circle and at the same time to be in sad contradiction with facts. A hallucination may be regarded as a fallacious percept, but it is not on that account an image; a hallucination is a percept and is essentially sensory in character. The fact of a percept being fallacious does not in the least imply that it is 'imaginary' and not sensory.
The ambiguity of the word 'imaginary' has not a little contributed to the psychological fallacy helping towards the confusion of image and sensation. ”

“ There is not a particle of evidence to substantiate the view that ideas or images are copies of sensations in the sense of being weak sensations or 'centrally excited sensations. There is nothing of the sensory in the idea. The weakest sensation cannot compare with the most vivid representation.
The laboratory experiments on that subject (Münsterberg and Külpe) are inconclusive as they either deal with incompletely perceived impressions, or with minimal sensations. ”

“ The primary elements are initiated directly by incoming peripheral stimulations, while the secondary sensory elements are brought about indirectly, through the mediacy of the primary elements, the secondary elements themselves being really derived from sense-organs others than the ones directly stimulated by the peripheral excitation. ”

“ As a matter of fact hallucinations are not made up of images, but of sensory elements; while on the contrary hypnotic hallucinations are not made up of sensory elements, but of images. Hallucinations are not due to 'images' but to actual sensations. Psychologically regarded, hallucinations do not differ in their make-up from ordinary percepts. ”

“ It shows that a revived impression is itself an impression, and not an idea." In his Manual of Psychology he says "that at bottom the distinction between image and percept is based on a difference of quality." ”

“ Now 'imaginary' used in the sense of lack of an external object by no means implies the psychological sense of consisting of images. A hallucination is commonly said to be imaginary in the sense of not having an objective reality, but we have to prove yet that it consists of images. ”

“ We then speak of them as hallucinations (?) ; and they enter into a disastrous competition with the real material of perception, completely transcending the boundary line which so usefully divides it from the material of imagination." Külpe admits that there is no intensity to the image, that there is no variation in 'intensity' of images, an 'attribute' characteristic of percepts. Psychologically regarded, this in itself shows the qualitative difference between image and percept. ”