In this book, Darwin seeks to trace the origins of such human characteristics as the lifting of the eyebrows in moments of surprise and the mental confusion which typically accompanies blushing. Darwin links mental states to the neurological organization of movement; and he sought out the opinions of some leading British psychiatrists, notably James Crichton-Browne, in the preparation of the book which forms his main contribution to psychology. Amongst the innovations with this book are Darwin's circulation of a questionnaire in his preparatory research; simple experiments on emotional recognition among his friends and family; and (borrowing from Duchenne de Boulogne) the use of photographs in its presentation of scientific information. The Expression of the Emotions is an important landmark in the history of book illustration.