Preliminary process theory: towards an integrated account of the psychophysiology of cognitive processes.

A brief overview of the history of the orienting reflex (OR) in western psychology is presented, in order to provide a context for a discussion of its role in attentional processing. Some aspects of observed response fractionation are discussed, leading to an outline of a coherent theory of preliminary processes in OR elicitation. This discriminates between involuntary and voluntary aspects of cognitive processing but depends on a common core mechanism. The role of state variables in modulating phasic responses is also discussed. Although this theory was developed largely from a study of autonomic responses, it has been possible to extend it to include various central measures, and recent extensions are described. A number of recent studies are briefly outlined to provide examples demonstrating the use of a range of physiological measures (central and peripheral) in a variety of situations (from pistol range to the laboratory) with different subject groups (adults, children and psychiatric patients). Finally, the use of heart rate data in the investigation of task-relevant cognitive load is discussed as a relatively simple but sensitive index to explore drug and other effects in cognition. These examples indicate the wide-ranging potential benefits of using psychophysiological approaches in the study of cognitive processes.