Parts of Response Related to Consciousness

The sketch of the nature of response which we have just given is so greatly simplified with respect to the actual facts that it is hardly more than a symbolic representation of the latter. However, before proceeding to consider the ways in which concrete response mechanisms are complicated by the introduction of further details of structure, it may be well to indicate the general relation which obtains between the psychical terms and processes and the typical diagram of response. In the first place, we must recognize that the general psychophysical relation is one of mathematical interdetermination, as represented by functions or equations. This means simply that, given certain aspects of the response, the conscious processes follow--or, more strictly speaking, occur simultaneously. There is no structural linkage between the two things; they are merely logically or mathematically correlated, so that one can be inferred from the other. Neither one is logically prior to the other.

The next question is as to what particular aspects of the response are concerned in this relationship. Many different answers have been given to this question. Common sense is apt to refer experience primarily to the object of the response. Earlier psychologists tended to emphasize the stimulus and sensory activities, while some moderns have tried to associate the psychical processes essentially with the motor or efferent stages. However, all available empirical data support the view that the direct correlation of consciousness is limited to the central or adjustor stage; the relationship to other stages being due to the linkage between them and this central activity. This view of the correspondence between the psychical factors and those of response explains all of the facts of common observation, as well as those of the laboratory or clinic. The apparent dependency of our sensations and perceptions upon the objects before our organisms, or the forces which are acting upon our sense-organs, is referable to the fact that the central or brain process is determined by the train of conduction which is initiated by these agencies. The character of the central activity then determines that of consciousness. In a similar way, the seeming control which our conscious volition exercises over our muscular behavior is referable to the fact that the central mechanism governs the latter and is also a function of the psychical operations. The idea of the exclusive direct relationship of mind and brain has led some thinkers to speak of the brain as "the seat of consciousness," but it is evident that this can only be regarded as a figure of speech. There is no way in which we can conceive of consciousness as being located in the brain, or as being integrally associated with the central nerve processes.

We may now return to consider some of the complications of the response mechanism. The symbolic response structure which we have already outlined is not even sufficiently complex to correspond with the simplest "reflexes." All actual reflexes involve at least three nerve conductors in series, instead of two, the third one being interpolated between the afferent and the efferent conductors of our sketch. At the same time, the conduction is never limited to the pathway through a single chain of fibres, but occurs simultaneously in parallel along a very considerable number of such units. The existence of these parallel lines of conduction is responsible for some of the most striking features of response, particularly in human beings. On the afferent side, the exact distribution of the parallel excitations creates a pattern of conduction which is a controlling feature in the more complex forms of response. On the efferent side, the multiplicity of outwardly conducting paths presents alternatives from which the actual motor outlets must be chosen in accordance with the bias of the adjustor mechanism.