Impaired spontaneous anthropomorphizing despite intact perception and social knowledge

Abstract

Humans spontaneously imbue the world with social meaning: we see not only emotions and intentional behaviors in humans and other animals, but also anger in the movements of thunderstorms and willful sabotage in crashing computers. Converging evidence supports a role for the amygdala, a collection of nuclei in the temporal lobe, in processing emotionally and socially relevant information. Here, we report that a patient with bilateral amygdala damage described a film of animated shapes (normally seen as full of social content) in entirely asocial, geometric terms, despite otherwise normal visual perception. Control tasks showed that the impairment did not result from a global inability to describe social stimuli or a bias in language use, nor was a similar impairment observed in eight comparison subjects with damage to orbitofrontal cortex. This finding extends the role of the amygdala to the social attributions we make even to stimuli that are not explicitly social and, in so doing, suggests that the human capacity for anthropomorphizing draws on some of the same neural systems as do basic emotional responses.

Fig. 1.

Structural MRI of SM's brain. Axial and coronal slices (A and C) show the lack of signal at the amygdala, but a coronal slice at the level of the hippocampus (B) shows that this structure is intact. (Photographs courtesy of the Human Neuroimaging and Neuroanatomy Laboratory, Department of Neurology, University of Iowa.)

Fig. 2.

A scene from the classic Heider and Simmel (4) movie.

Fig. 3.

Comparison of word counts in descriptions given by SM and by normal controls. Percentages of words used in the three categories of interest: Affect, Social Processes, and Movement (see text). SM's word use percentages are indicated for the first (X) and second (star) testing sessions, and normal controls by circles (their mean and SD are also shown). liwc, linguistic inquiry and word count.