ABSTRACT
The definition of the object is, as we have seen, that it exists partes extra partes, and that consequently it acknowledges between its parts, or between itself and other objects only external and mechanical relationships, whether in the narrow sense of motion received and transmitted, or in the wider sense of the relation of function to variable. Where it was desired to insert the organism in the universe of objects and thereby close off that universe, it was necessary to translate the functioning of the body into the language of the initself and discover, beneath behaviour, the linear dependence of stimulus and receptor, receptor and Empfinder.1 It was of course realized that in the circuit of behaviour new particular forms emerge, and the theory of specific nervous energy, for example, certainly endowed the organism with the power of transforming the physical world. But in fact it attributed to the nervous systems the occult power of creating the different structures of our experience, and whereas sight, touch and hearing are so many ways of gaining access to the object, these structures found themselves transformed into compact qualities derived from the local distinction between the organs used. Thus the relationship between
stimulus and perception could remain clear and objective, and the psycho-physical event was of the same kind as the causal relations obtaining ‘in the world’. Modern physiology no longer has recourse to these pretences. It no longer links the different qualities of one and the same sense, and the data of different senses, to distinct material instruments. In reality injuries to centres and even to conductors are not translated into the loss of certain qualities of sensation or of certain sensory data, but into loss of differentiation in the function. We have already discussed this: wherever the seat of the injury in the sensory routes and whatever its origin, one observes, for example, a decay of sensitivity to colour; at the beginning, all colours are affected, their basic shade remaining the same, but their saturation decreasing; then the spectrum is simplified and reduced to four colours: yellow, green, blue, crimson, and indeed all short-wave colours tend towards a kind of blue, all long-wave colours towards a kind of yellow, vision being liable, moreover, to vary from moment to moment, according to degree of fatigue. Finally a monochrome stage in grey is reached, although favourable conditions (contrast, long exposure) may momentarily bring back dichromic sight.2 The progress of the lesion in the nervous tissue does not, therefore, destroy, one after another, ready-made sensory contents, but makes the active differentiation of stimuli, which appears to be the essential function of the nervous system, increasingly unreliable. In the same way, in the case of noncortical injury to the sense of touch, if certain contents (temperatures) are more easily destroyed and are the first to disappear, this is not because a determinate region, lost to the patient, enables us to feel heat and cold, since the specific sensation will be restored if a sufficiently extensive stimulus is applied;3 it is rather that the sensation succeeds in taking its typical form only under a more energetic stimulus. Central lesions seem to leave qualities intact; on the other hand they modify the spatial organization of data and the perception of objects. This is what had led to the belief in specialized gnosic centres for the localization and interpretation of qualities. In fact, modern research shows that central lesions have the effect in most cases of raising the chronaxies,
which are increased to two or three times their normal strength in the patient. The excitation produces its effects more slowly, these survive longer, and the tactile perception of roughness, for example, is jeopardized in so far as it presupposes a succession of circumscribed impressions or a precise consciousness of the different positions of the hand.4
