Review of Perception and Communication.

Abstract

their action upon their common paths seem to lie at the very root of the great psychical forces of attention '. There are two reasons why this line of approach is particularly topical at the present day.The first of them is a theoretical one the current popularity of language, derived from communication theory, for the statement of psychological problems. Owing perhaps to the accident that psychologists working on hearing are naturally those in closest contact with telephone engineers, this popularity has been at its greatest in the auditory field. It may well be that too much has been expected from a purely linguistic device, which by itself will not provide the answer to the problems of psychology-Gregory (1953) has rightly pointed out that considering the brain as a computing machine produces the old problem of * atomism or Gestalt ? ' in the new language of ' digital or analogue }\ But new vocabularies do involve some shift in basic assumptions, and perhaps the point of permanent value which will remain in psychology if the fashion for communication theory wanes, will be the emphasis on problems of capacity.The latter, in communication theory, is a term representing the limiting quantity of information which can be transmitted through a given channel in a given time : if we send Morse code with a buzzer we cannot send a dot and a dash at the same time but must send them successively. An array of X buzzers would allow us to send x dots and dashes at once, provided we had a listener who could distinguish them.* The fact that any given channel has a limit is a matter of central importance to communication engineers, and it is correspondingly forced on the attention of psychologists who use their terms. Any hypothetical account of brain function must in future consider on the one hand the size of the brain (how many buzzers there are) and on the other hand the rate at which that brain will make reactions to a given set of incoming stimuli (the number of dots and dashes per second). * We will give an amplified account of capacity in Chapter 3, but still in non-technical and therefore inexact terms. For precise definitions of this and other terms in communication theory, reference should be made to the excellent glossary given by MacKay (in von Foerster 1952). All such terms are used in this book with MacKay's definitions, though they are introduced in popular language. 6 PERCEPTION AND COMMUNICATION This possibility, that one chain of events physically excludes another, has been somewhat neglected in physiology and psychology, though not of course completely. Sherrington is a siriking instance to the contrary, since his account of competition between different reflexes for common paths is essentially based on questions of capacity. But any account in which completely separate neural areas or pathways are postulated for different activities, neglects the possible use of the concept of capacity to explain the interference of these activities: and these types of account are common. Pavlovian theory, for instance, ...