How the brain represents other minds

Abstract

How does the brain represent the world? Sensory neuroscience has given us a detailed window into how the brain represents physical objects in our environment: For instance, the shape, color, and direction of motion of visual stimuli are represented in an orderly fashion in higher order visual cortices. But we also represent social objects: other people and their thoughts, beliefs, and feelings. How is that kind of knowledge represented in the brain? In an ambitious new study in PNAS, Tamir et al. (1) used functional MRI (fMRI) to argue that our brains represent other minds along three broad dimensions: social impact, rationality, and valence. The approach taken by the authors is straightforward to understand by analogy. For example, we could represent any specific place on earth we have visited as a unique combination of a large number of variables: altitude, temperature, humidity, light, chemical composition of the air, and so forth. Despite the enormous number of different variables, you could quickly tell me which of these visits were more similar to one another: Standing on top of Mont Blanc would be more similar to standing on top of Mount Whitney than to lying on your towel on a beach in Aruba. To judge such similarities, you do not need to recollect all of the details; a few coarse dimensions suffice. We do the same thing when we think about other people, Tamir et al. (1) argue. Psychologists have attempted to capture the specific dimensions by which we represent others in several theories, from which the study extracted 16 dimensions for further investigation (Fig. 1A). Importantly, prior work on these dimensions was based largely on theory and on behavioral data. Tamir et al. (1) looked to the brain for further evidence.