Investigating neural synchrony in intimate couples and roommates using electroencephalography during naturalistic emotional stimuli

Abstract

Prior research has suggested that romantic couples exhibit greater inter-brain synchrony than other dyads; however, these findings may be confounded by differences in shared experience. This thesis examined how relationship type, relationship satisfaction, emotional similarity, and social proximity contribute to neural synchrony during naturalistic emotional processing. To address this, the present study compared romantic couples and roommate dyads using electroencephalography (EEG) and phase lag index (PLI) analysis while participants viewed emotionally evocative stimuli with positive, negative, and neutral valence. Results provided limited support for the relationship-type differences in neural synchrony. Although some effects suggested greater synchrony in couples, particularly in frontal regions during emotionally arousing conditions, these effects were not robust and did not survive correction for multiple comparisons. Relationship satisfaction and emotional similarity were also not consistently associated with neural synchrony. In contrast, relationship duration was positively correlated with neural synchrony in both couples and roommates, with significant associations observed in the theta band that survived correction for multiple comparisons. These findings suggest that neural synchrony during naturalistic experiences may be better explained by shared experience and social proximity rather than relationship category alone. The results highlight the importance of considering interaction history and familiarity when interpreting inter-brain synchrony and contribute to a more nuanced understanding of the mechanisms underlying neural alignment in social contexts.