Darwin's sources on emotional expression

Darwin attended debates about psychology at the Plinian Society in December 1826 and March 1827 as a medical student at Edinburgh University. These were prompted by the publication of Charles Bell's Anatomy and Philosophy of Expression (1824). In his presentations, the phrenologist William A.F. Browne ridiculed Bell's theological explanations, pointing instead to the similarities of human and animal biology. Both meetings ended in uproar. Darwin revisits these debates 45 years later and refers to Duchenne de Boulogne's Mécanisme de la physionomie humaine (1862) as he shifts the debate from philosophical to scientific discourse and highlights the social value of facial expression over other forms of expression in vocalisations, tears, and posture.

Darwin's response to Bell's natural theology is discussed in Lucy Hartley's Physiognomy and the Meaning of Expression in Nineteenth Century Culture (2001).^[23]

In the composition of the book, Darwin drew on a variety of sources:

• His questionnaire (circulated in the early months of 1867) concerning emotional expression in different ethnic groups
• Anthropological memories from his time on HMS Beagle
• Conversations with livestock breeders and pigeon fanciers
• Observations on his infant son William Erasmus Darwin (A Biographical Sketch of an Infant, published in 1877 in the philosophical journal Mind), on his family's dogs and cats, and on the orangutans at London Zoo
• Simple psychology experiments with members of his family concerning the recognition of emotional expression
• The neurological insights of Duchenne de Boulogne, a physician at the Salpêtrière asylum in Paris
• Hundreds of photographs of actors, babies, and children, including photographs by Oscar Rejlander
• Descriptions of psychiatric patients in West Riding Pauper Lunatic Asylum in Wakefield

As a result of his domestic psychology experiments, Darwin reduced the number of commonly observed emotions from Duchenne's calculation of more than sixty facial expressions to six "core" expressions: anger, fear, surprise, disgust, happiness, and sadness.

Darwin corresponded with James Crichton-Browne, the son of the phrenologist William A. F. Browne and now the distinguished medical director of West Riding Pauper Lunatic Asylum. At the time, Crichton-Browne was editing The West Riding Lunatic Asylum Medical Reports. Recognising the significance of Crichton-Browne's contributions, Darwin suggested to him that Expression "ought to be called by Darwin and Browne?"

Darwin also drew on his personal experience of the symptoms of bereavement and studied the text of Henry Maudsley's 1870 Goulstonian Lectures on Body And Mind.

Darwin considered other approaches to the study of emotions, such as their depiction in the arts—as discussed by the actor Henry Siddons in his Practical Illustrations of Rhetorical Gesture and Action (1807) and by the anatomist Robert Knox in his Manual of Artistic Anatomy (1852)—but abandoned these approaches as unreliable.

It is noteworthy that only a few sections in Expression touch on emotional deception.