Feature absence-presence and two theories of lapses of sustained attention.

We conducted two experiments using search asymmetry to test two theories of sustained attention lapses currently debated in the literature: the mindlessness theory and the resource theory. In the first experiment, participants performed a feature present and a feature absent sustained attention to response task (SART). The mindlessness theory predicts more commission errors in a feature present SART than a feature absent SART, while resource theory predicts the reverse, i.e. more commission errors in a feature absent SART than feature present SART. The latter occurred. In the second study, participants performed a naturalistic scene vigilance task with targets more analogous to a feature present search or more analogous to a feature absent search. The vigilance decrement occurred, with an increase in reaction time to targets over the course of the vigil. The decrement was more pronounced with the targets more analogous to a feature absent search. Overall, the results of both studies support a resource theory of sustained attention lapses, not the mindlessness theory.