The Theory of Search. II. Target Detection

“Kinematic bases,” the first paper of this series, discussed the geometric and kinematic factors involved in search—the positions, motions, and contacts of observers and targets. Probability was introduced only in assuming specific relative positions for the observer and target.

The present paper discusses the uncertainties inherent in the act of detection under various specific conditions of contact. In the course of the discussion a body of methods for applying probability to problems of detection is developed. It must be emphasized, however, that these methods are conditioned by the particular situation in the case of visual detection because the different elementary acts of looking or “glimpses” are essentially independent trials. The reason for the distinction follows.