The Mirror and the Mind traces the history of the mirror self-recognition test—the experiment of placing subjects in front of a mirror and looking for signs of self-recognition—showing how it became a privileged site for addressing questions about human nature.From its origins in the Enlightenment period, the mirror test provided a way of reconciling notions of human specificity with discourses, such as Darwinism, that threatened to dissolve the boundaries between humans and other creatures. Babies might begin with mental capabilities comparable to those of lower animals, but once they were able to recognize themselves in a mirror (at around 18 months), they breached a new level of existence, and left all other animals behind.

The high hopes placed in the mirror, however, were soon put to a serious test. As I show in the book, the responses to the mirror were surely suggestive, but it turned out to be extremely difficult to know exactly what they meant. If an animal attacked the mirror, did this suggest that it took the mirror image to be another animal? If a child smiled at its image, was this a sign of self-recognition? In response, researchers developed a set of methods, standardizing mirror situations, building national and international networks of baby observation, and relying on a set of media of observation such as note-taking, film, and video. In the course of these developments, the earlier ambitious goals of mirror testing were sometimes lost: instead of self-recognition, the mirror was used to elicit a specific set of behaviors related to other social and cognitive functions.