Brain Systems Underlying Fundamental Motivations of Human Social Conformity

One step too far: social cerebellum in norm-violating navigation

Social norms are pivotal in guiding social interactions. The current study investigated the potential contribution of the posterior cerebellum, a critical region involved in perceiving and comprehending the sequential dynamics of social actions, in detecting actions that either conform to or deviate from social norms. Participants engaged in a goal-directed task in which they observed others navigating towards a goal. The trajectories demonstrated either norm-violating (trespassing forbidden zones) or norm-following behaviors (avoiding forbidden zones). Results revealed that observing social norm-violating behaviors engaged the bilateral posterior cerebellar Crus 2 and the right temporoparietal junction (TPJ) from the mentalizing network, and the parahippocampal gyrus (PHG) to a greater extent than observing norm-following behaviors. These mentalizing regions were also activated when comparing social sequences against non-social and non-sequential control conditions. Reproducing norm-violating social trajectories observed earlier, activated the left cerebellar Crus 2 and the right PHG compared to reproducing norm-following trajectories. These findings illuminate the neural mechanisms in the cerebellum associated with detecting norm transgressions during social navigation, emphasizing the role of the posterior cerebellum in detecting and signaling deviations from anticipated sequences.

Neural asymmetry in aligning with generous versus selfish descriptive norms in a charitable donation task

Social alignment is supported by the brain's reward system (ventral striatum), presumably because attaining synchrony generates feelings of connectedness. However, this may hold only for aligning with generous others, while aligning with selfishness might threaten social connectedness. We investigated this postulated asymmetry in an incentivized fMRI charitable donation task. Participants decided how much of their endowment to donate to real charities, and how much to keep for themselves. Compared to a baseline condition, donations significantly increased or decreased in function of the presence of descriptive norms. The fMRI data reveal that processing selfish norms (more than generous ones) recruited the amygdala and anterior insula. Aligning with selfish norms correlated on average with reduced activity in the lateral prefrontal cortex (LPFC) and, at the individual level, with decreasing activity in the ventral striatum (VS). Conversely, as participants aligned more with generous norms, they showed increasing activity in the LPFC and, on average, increased activity in the VS. This increase occurred beyond the increased VS activity which was also observed in the baseline condition. Taken together, this suggests that aligning with generosity, while effortful, provides a "warm glow of herding" associated with collective giving, but that aligning with selfishness does not.

Adaptive adjustment after conflict with group opinion: evidence from neural electrophysiology

Individuals inherently seek social consensus when making decisions or judgments. Previous studies have consistently indicated that dissenting group opinions are perceived as social conflict that demands attitude adjustment. However, the neurocognitive processes of attitude adjustment are unclear. In this electrophysiological study, participants were recruited to perform a face attractiveness judgment task. After forming their own judgment of a face, participants were informed of a purported group judgment (either consistent or inconsistent with their judgment), and then, critically, the same face was presented again. The neural responses to the second presented faces were measured. The second presented faces evoked a larger late positive potential after conflict with group opinions than those that did not conflict, suggesting that more motivated attention was allocated to stimulus. Moreover, faces elicited greater midfrontal theta (4-7 Hz) power after conflict with group opinions than after consistency with group opinions, suggesting that cognitive control was initiated to support attitude adjustment. Furthermore, the mixed-effects model revealed that single-trial theta power predicted behavioral change in the Conflict condition, but not in the No-Conflict condition. These findings provide novel insights into the neurocognitive processes underlying attitude adjustment, which is crucial to behavioral change during conformity.

A frontopolar-temporal circuit determines the impact of social information in macaque decision making

When choosing, primates are guided not only by personal experience of objects but also by social information such as others' attitudes toward the objects. Crucially, both sources of information-personal and socially derived-vary in reliability. To choose optimally, one must sometimes override choice guidance by personal experience and follow social cues instead, and sometimes one must do the opposite. The dorsomedial frontopolar cortex (dmFPC) tracks reliability of social information and determines whether it will be attended to guide behavior. To do this, dmFPC activity enters specific patterns of interaction with a region in the mid-superior temporal sulcus (mSTS). Reversible disruption of dmFPC activity with transcranial ultrasound stimulation (TUS) led macaques to fail to be guided by social information when it was reliable but to be more likely to use it when it was unreliable. By contrast, mSTS disruption uniformly downregulated the impact of social information on behavior.