The history of research on the pupillary light reflex goes back to 1765. Since 1960, particularly after 1965, the interest of psychologists and other behavioral and social scientists in the pupillometry response had increased enormously. Originally published in 1977, Pupillometry offered an extensive review and assessment of the existing psychological research on the pupil, focusing not only on recent work, but also summarizing and evaluating much research that, up until then, was unpublished or unavailable. Today it can be read in its historical context.