Attention control: explorations of the work of an executive controller.

This contribution reviews three lines of studies set to investigate attention control and executive operations, in the general context of the interplay between bottom-up and top-down processes in the conduct of proficient behavior. One line of studies focused on the act of switching attention between tasks and the mental costs associated with it. A second group of experiments investigated attention strategies and resource management in coping with high load and concurrent task demands. A third line of studies examined the influence of enhanced knowledge and accumulated experience on coping with malfunctions and mishaps in system response. The experimental results of all studies lend strong support to the existence and influence of executive control processes. These types of processes operate on the established representations and knowledge bases of tasks, to make the best use of processing and response facilities. The experiments shed light on the nature of the processes and the variables that influence them. It is shown that proficient performance is far from being exclusively guided by automatic processing and response routines triggered directly by events in the environment. Instead it is a joint and non-trivial product of these two types of processes. Executive control is required not only in early stages of training, but also at high levels of mastery and proficiency. Automatism does not eliminate or reduce the importance of executive control and strategic behavior. A new and powerful class of processes comes into play at this level of expertise, with strong influence on modes of behavior and the overall efficiency of performance.