The ability to appropriately attend to environmental demands is critical for successful survival and development. In the study of human behavior, assess ments of individual differences in the ability to attend have been used as diagnostic criteria for the identification of a number of psychological disor ders. For example, an inability to attend appropriately has been associated with the diagnosis of mental retardation, schizophrenia, autism, hyperactiv ity, senility, and learning disabilities. The construct of attention has been studied from various theoretical orientations. Much of the attention literature is found within the domain of cognitive psychology and has focused on behavioral indicators of stimulus detection and information processing (e.g., Kahneman, 1973; Posner, 1978; Shiffrin & Schneider, 1977).