An Empirical Formula for Visual Search
Operations Research · 1986 · Volume 34 · Issue 3
Abstract
This paper presents an empirically derived formula for computing the threshold contrast C for visually detecting distant objects in search situations. The threshold contrast is the value of contrast that produces detection probability 1/2 on a single glimpse of about 1/3 to 1 second in duration. The formula allows one to compute C as a function of background luminance, target angular area A , and an empirically determined constant K . For small A , the formula reduces to Ricco's law, which says that the threshold constrast C , and Area A , are directly proportional for small values of A . The limiting threshold contrast is determined by K . Results of fitting this formula to a set of observational data are shown. The formula provides a useful approximation for determining detection capability for planning visual searches.
Keywords
751 visual search
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