Head, Belt, Boots: Obtaining Consistent Probability of Detection in Human Visual Search

A key lost-person search method is the “grid team,” a line of searchers moving abreast through the woods. The optimum spacing for such searchers is not clear, however. We have determined the spacing necessary for searchers to see their immediate neighbors’ head, belt, or boots at sites in West Virginia in the summer and in Pennsylvania in the summer and winter. An analysis of the probabilities of detection (PODs) expected from previously or newly measured effective sweep width (W) values in those locations for each of these spacings suggests that each offers a consistent and useful POD for a given search object that does not appear to be affected by location or season by an operationally significant amount. KEYWORDS: SAR, effective sweep width, probability of detection, search theory