In the decade since the pupillary light reflex to light was first studied using a linear transfer function approach [18, 20], many developments in control theory and in research into biological control systems have occurred. Optimal control theory, Liapunov stability methods, Wiener-G functional analysis, general systems identification procedures and pattern recognition techniques for adaptive systems have influenced experimental approaches to a wide variety of neurological control systems. An intensive reinvestigation using classical electrophysiological techniques to define interesting design features of the underlying neurophysiological mechanisms of these systems is now proceeding, and it appears that clinical applications are on the horizon. Three contemporary experimental approaches to the pupillary system will be described in detail and shown to result in complementary views. 1. (A) Wiener-G functional analysis using both random and time domain inputs [10]. 2. (B) Statistical communication analysis of pupil noise [12, 16], and 3. (C) Neurophysiological techniques embedded within a systems approach [19]. © 1969.
