Visual search is a key paradigm in attention research that has proved to be a test bed for competing theories of selective attention. The starting point for most current theories of visual search has been Treisman’s ‘‘feature integration theory’’ of visual attention (e.g., Treisman & Gelade, 1980). A number of key issues that have been raised in attempts to test this theory are still pertinent ...

Behaviour has two levels, which we will call strategic and tactical. At the strategic level the organism has to choose which particular activity to pursue at any given time (e.g., looking for food, finding a sexual partner, escaping from dangers, sleeping). At the tactical level it must implement the particular sequence of actions that makes it possible to achieve the goal of the chosen activit...