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Individuals use social information to guide social interactions and to update relationships along multiple social dimensions. However, it is unclear what neural basis underlies this process

of abstract “social navigation”. In the current study, we recruited twenty-nine participants who performed a choose-your-own-adventure game in which they interacted with fictional characters

during fMRI scanning. Using a whole-brain GLM approach, we found that vectors encoding two-dimensional information about the relationships predicted BOLD responses in the hippocampus and

the precuneus, replicating previous work. We also explored whether these geometric representations were related to key brain regions previously identified in physical and abstract spatial

navigation studies, but we did not find involvement of the entorhinal cortex, parahippocampal gyrus or the retrosplenial cortex. Finally, we used psychophysiological interaction analysis and

identified a network of regions that correlated during participants’ decisions, including the left posterior hippocampus, precuneus, dorsolateral prefrontal cortex (dlPFC), and the insula.

Our findings suggest a brain network for social navigation in multiple abstract, social dimensions that includes the hippocampus, precuneus, dlPFC, and insula.

A fundamental feature of our social world is social interaction, or the ways in which people reciprocally respond to one another. Imagine you are about to leave your office at 5 pm, but your

boss asks you to stay for another hour. What will you do? In deciding, you may take your relationship into account, such as how close you are to your boss, or how much power they wield over

you. These social relationships can be thought of occurring in a two-dimensional (2D) social space of affiliation and power1,2,3. Similar to navigating in physical space4, social decisions

may represent a kind of navigation through abstract social dimensions—so-called social navigation3, which relies on the formation and utilization of a cognitive map5.

Experimental design. (a) Illustration of the experimental procedures. In the narrative trials, the participants watched slides that provided background information about the story or the

words of a fictitious character in a grey bubble. In the option trials, the participant made a decision in a blue bubble followed by a black screen. Baseline: a black screen slide was

analyzed as the baseline. (b) The trajectory of main characters in the 3D social space. (c) The trajectory of main characters in the 2D social space.

Coordinates of the characters in the story. (a) Schematic diagram for the 2D social map. In this 2D space, x-axis represents affiliation dimension and y-axis represents power dimension. The

coordinate (x, y) represents the location of the character during the social interaction process. The participant was located at (6, 0) and the starting point for the characters was (0, 0).

V represents the social distance between the participant and the character, and the angle represents the first-person orientation of the participant during each choice. (b/c) Plot of the

length and angle for the vector V (V, θ). Asterisks indicate significant differences in the final locations between each pair of characters in the story. *p