On the comparison of conspicuity with visibility
Abstract Attentional limits are mostly inferred from reaction time experiments in which a decrease in speed or accuracy is observed as the number of non-targets increases. Search for targets defined by one or more unique features has been found to be little affected by the number of non-targets, but search time for conjunction targets usually increases with the number of distractors (Treisman and Gelade, 1980). In the present paper, an alternative method has been used to investigate whether visual search for a conjunction target and a unique target requires attention or not. The results suggest that both targets, characterized by either a unique feature or a conjunction, profit from directed attention. It is concluded that reaction time tasks alone are invalid for differentiating controlled from automatic search processes.