Derivation and test of an optimum overlapping-lobes model of visual search

The visual search process is modeled as a sequence of fixations which may or may not partially overlap in coverage of the search field. A single expression is derived for the probability of search success which covers all overlap cases. Making the further assumption that search strategy is chosen so as to maximize expected value, yields the result that each point on the search field must be fixated an integral number of times. In an experiment where visual lobe size and fixation duration were controlled, human subjects behaved in a manner close to that predicted by the optimization model. It is concluded that further development of the model using less restrictive assumptions is warranted.