C. B. Duchenne du Boulogne was a pioneering neurophysiologist as well as an innovative photographer. In "The Mechanisms of Human Facial Expression", first published in French in 1862, his fascinating photographs and insightful commentary provided generations of researchers with foundations for experimentation in the perception and communication of human facial affect Subsequent researchers from Darwin to Ekman all acknowledge their debt to Duchenne and this fascinating little book, with its truly remarkable photographs, makes excellent reading even today.
Duchenne's principal photographic subject,
"The Old Man",
was afflicted with almost total facial anaesthesia. This
circumstance made him an ideal subject for Duchenne's investigations,
because the stimulating electrodes he used were certainly somewhat
uncomfortable, if not actually painful.