TRANSCUTANEOUS AURICULAR VAGUS NERVE STIMULATION INCREASES EMPATHIC CHOICE TOWARD OUTGROUP NEGATIVE EMOTIONS.

Abstract

Objective: To investigate whether transcutaneous auricular vagus nerve stimulation (taVNS) modulates empathic choice, and whether any such effect differs for ingroup versus outgroup targets, in a single-session behavioural experiment.

Methods: Twenty-eight healthy East Asian participants were randomly assigned to active taVNS or sham stimulation groups. After 15 minutes of stimulation, participants completed an adapted Empathy Selection Task (EST), choosing to empathize with or describe facial expressions of ingroup (Asian) and outgroup (African) targets displaying negative emotions. Because the design was exploratory and the sample small, a generalized linear mixed model (GLMM) with a binomial distribution and logit link, modeling subject-level random intercepts, was used and effects are reported as odds ratios (OR) with 95% confidence intervals (CI).

Results: The sham group showed significantly lower empathic choice than the active group (β = -0.82; OR = 0.44, 95% CI [0.22, 0.90], p = 0.024). The main effect of target ethnicity was non-significant (OR = 0.88, 95% CI [0.60, 1.28], p = 0.494), indicating no detectable baseline ingroup bias. A group × ethnicity interaction (OR = 1.74, 95% CI [1.01, 3.00], p = 0.048) indicated that the taVNS effect was selectively larger for outgroup targets; this pattern survived parametric bootstrap (bootstrap p = 0.022) and Bayesian reanalysis (96.7% of the posterior above zero), though its credible interval narrowly included no effect, marking it as supported but not decisive.

Conclusion: taVNS may increase motivational empathy and selectively enhance empathic choice toward outgroup negative emotions. These exploratory findings are consistent with, but do not directly test, the aversiveness reduction hypothesis, and require replication with autonomic measures and larger samples.