In the first half of the sixties, general notions were formulated concerning the functional role of the orienting reaction (OR) in adaptive activity, its elicitation and habituation. These notions included the following: a) The OR is elicited only by significant changes in a situation. This implies that OR elicitation is preceded by brain processes (usually unconscious) pertaining to the evaluation of the significance of changes according to an existing hierarchy of motivations, attitudes, and goals. Therefore, the OR is of an active (vs. reactive) nature, i.e., is inevitably determined by internal factors of brain activity. b) The OR is not a unitary reaction, but a complex polyfunctional activity, different aspects of which are reflected in different OR components which can be modified rather independently. c) The OR represents the processes of organizing new (non-standard) actions: sensory, motor, or intellectual. OR habituation is a manifestation of attenuation of the active control of an action, and an increase in its automation. Thus, the emphasis in understanding the OR has shifted from a predominantly "sensualistic" platform to a predominantly "actualistic" one. In recent experiments, the role of emotional processes in the elicitation and habituation of components of the OR has been analyzed. Complex relations between the GSR and anxiety were found in a study of patients with acute alcohol withdrawal syndrome treated with different psychopharmacological agents. The study of auditory evoked potential habituation in depressive patients has shown the emotional state influence on sensory aspects of the OR with the participation of the OR brain mechanisms in perceptual defense.(ABSTRACT TRUNCATED AT 250 WORDS)