Personal space regulation by the human amygdala

Abstract

The amygdala plays key roles in emotion and social cognition, but how this translates to face-to-face interactions involving real people remains unknown. We found that an individual with complete amygdala lesions lacked any sense of personal space. Furthermore, healthy individuals showed amygdala activation upon close personal proximity. The amygdala may be required to trigger the strong emotional reactions normally following personal space violations, thus regulating interpersonal distance in humans.

Figure 1

Lesion Study: Mean preferred distances from the experimenter. (A) SM's (red) preference was the closest distance to the experimenter (black), compared to age-, gender-, race-, and education-matched controls (purple, n = 5), as well as general comparison subjects (blue, n=15). (B) SM's mean preferred distance away from the experimenter (image drawn to scale). (C) Control participants’ mean preferred distance away from the experimenter, excluding the 3 largest outliers (image drawn to scale).

Figure 2

fMRI study: Activation of the amygdala by close (relative to far) interpersonal distance. (A) Coronal slices showing significantly activated voxels in the dorsal amygdala (cluster-level significance, p<0.05); scale shows t-value. (B) Contrast parameters (arbitrary units) for each of the eight subjects who participated in the experiment (extracted from and averaged across all significant voxels in (A); blue dots), along with the group mean (black line). Coordinates for the peak voxel are shown. Subjects were unable to see the position of the experimenter, but were informed of his location at all times. All experiments were approved by Caltech's Institutional Review Board, and informed written consent was obtained from all participants. See Supplementary Text for a detailed description of the experiment.