ATTENTION (from Lat. ad-tendo, await, expect; the condition of being "stretched" or "tense"), in psychology, the concentration of consciousness upon a definite object or objects. The result is brought about, not by effecting any change in the perceptions themselves, but simply by isolating them from other objects. Since all consciousness involves this isolation, attention may be defined generally as the necessary condition of consciousness. Such a definition, however, throws no light upon the nature of the psychological process, which is partly explained by the general law that the greater the number of objects on which attention is concentrated the less will each receive ("pluribus intentus, minor est ad singula sensus"), and conversely. There are also special circumstances which determine the amount of attention, e.g. influences not subject to the will, such as the vividness of the impression (e.g. in the case of a shock), strong change in pleasurable or painful sensations. Secondly, an exercise of volition is employed in fixing the mind upon a definite object. This is a purely voluntary act, which can be strengthened by habit and is variable in different individuals; to it the name "attention" is sometimes restricted. The distinction is expressed by the words "reflex" or "passive," and "volitional" or "active." It is important to notice that in every case of attention to an object, there must be in consciousness an implicit apprehension of surrounding objects from which the particular object is isolated. These objects are known as the "psychic fringe," and are essential to the systematic unity of the attention-process. Attempts have been made to examine the attention-process from the physiological standpoint by investigating the muscular and neural changes which accompany it, and even to assign to it a specific local centre. It has, for example, been remarked that uniformity of environment, resulting in practically automatic activity, produces mental equilibrium and the comparative disappearance of attention-processes; whereas the necessity of adapting activity to abnormal conditions produces a comparatively high degree of attention. In other words, attention is absent where there is uniformity of activity in accordance with uniform, or uniformly changing, environment. In spite of the progress made in this branch of study, it has to be remembered that all psycho-physical experiments are to some extent vitiated by the fact that the phenomena can scarcely remain normal under inspection.
See G.F. Stout, Analytic Psychology (London, 1896), especially part ii. chap. 2; also Psychology, Brain, etc.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)