Frances K. Graham, Barbara D. Strock and Bonnie L. Zeigler University of Wisconsin, Madison
Control systems, presumed to affect the flow of information, play a central role in many cognitive theories (e.g., Kahneman, 1973; Neisser, 1967; Posner, 1975). The systems are variously delineated and named-- alertness, arousal, activation, effort, attention, orienting, defense, and so on- -but at least three distinctions appear to be important: (1) whether the control is automatic, preattentive, and nonselective; (2) whether it affects the selection of inputs to be enhanced; and (3) whether it affects the speed and vigor of outputs. In a recent paper, Graham ( 1979, b) suggested that the operation of these three kinds of control might be reflected by changes in response to a probe blinkeliciting stimulus.
Although blinking is an unconditioned brainstem reflex, it can, like any reflex, be modified via efferent projections from cortical as well as many other levels of the nervous system (e.g., Lundberg, 1966; Sauerland, Knauss, Nakamura, & Clemente, 1967). Thus, in theory, it is potentially able to reflect processes and mechanisms at all levels. In fact, psychologists in the early decades of this century used the method of unconditioned reflex modification to advantage for analysis of sensory processing (e.g., Cohen, Hilgard, & Wendt, 1933; Peak, 1933; Yerkes, 1905). The method was then abandoned for several decades in favor of the study of instrumentally or classically conditioned, learned responses, but it has recently been revived in a number of laboratories (e.g., Hoffman & Wible, 1969; Ison & Leonard, 1971; Thompson & Spencer, 1966). In the meantime, understanding the neurophysiology of conditioned reflexes has advanced beyond knowledge of the associated behavioral phenomena.