Pupil Noise

Abstract

The random fluctuations of human pupillary area provide an interesting example of a stochastic process in a biological system. Statistical communication theory and system analysis have guided the authors in performing experiments which reveal important properties involved in the random process. The purpose of this paper is to present the various experiments performed during this investigation and to propose a system model which not only describes the average pupil response to a given stimuli but also the random fluctuations called pupil noise [33]. We classify these fluctuations as noise in the sense that noise usually connotes a signal which does not seem to serve any useful purpose. No attempt will be made here to describe the pupil physiology nor to present the mathematical foundations of the statistical theory. (For this background information, the reader is referred to references 12, 58–61 and Chapters 1 and 2.)