of emotion, these signs of a disturbed mentality are unerringly revealed by the delicate instruments of the psychologist.
The Factory Operative's Attention Power
In some factories the operative is called upon to simultaneously keep watch over a large number of parts of a moving mechanism, and to note and quickly correct a disturbance in any part. Eye and ear must have a wide range, must be able to take account of a large number of operations widely separated in space.
TESTING THE RANGE OF VISUAL ATTENTION. PRIVATE LABORATORY, SOCIETY OF APPLIED PSYCHOLOGY
For the scientific determination of the operative's range of visual attention, the "disc tachistoscope," shown facing page 106, may be used. This is a form of short-exposure apparatus. The essential idea is to furnish a field upon which
the subject may for a moment fasten his attention, and then to substitute for this field another containing certain prepared test-material. This last field is exposed for but a brief instant and removed, and the subject is then called upon to report all that he has seen during the last exposure. Tests of this kind have demonstrated that the range of visual attention is a comparatively constant quantity with each individual, having but little relation to general ability or intelligence and being but little affected by practice.
It matters not how painstaking the individual may be, he will fail in a test of this kind and at work of this kind if the type of attention that Nature gave him is unfitted for such an "expanded"
watchfulness. Yet in any type of work requiring a focusing of the attention upon a minute operation so as to note nice discriminations and detect subtle differences, he might prove a most excellent worker.
Kinds of Testing Apparatus