Neural synchrony in social interactions: Insights from romantic couples and deceptive dynamics

Neural synchronisation between individuals during social interactions is an emerging topic in neuroscientific research. However, little research has been conducted on brain dynamics in romantic and conflictual relational contexts. The present work integrates two hyperscanning electroencephalogram (EEG) studies examining (1) inter-brain synchrony (IBS) in romantic couples during emotional processing and (2) IBS during deceptive interactions using a mock crime task. The first EEG hyperscanning study involved 25 romantic couples. Participants completed self-report questionnaires to measure attachment levels and perform a task involving emotional visual stimuli. The task in the first phase required the two members of a couple to interact through direct gaze. Then, they looked at positive images together and interacted again through direct gaze, after which only one was exposed to negative images. The last phase consisted of a direct gaze within the couple. The results showed that, after one member of a couple was exposed to negative images, there was an increase in the IBS in the beta band at the frontoparietal level. Furthermore, IBS was positively correlated with levels of avoidant attachment and negatively correlated with levels of anxious attachment. The results suggest that emotionally valenced stimuli can influence IBS in romantic couples and can be associated with intra- individual levels of insecure attachment. The second study examined dyadic neurophysiological coupling during deceptive interactions using a mock crime paradigm with simultaneous EEG and ECG recordings in interviewer-interviewee dyads. The deception group (DG; N=15) demonstrated enhanced IBS in theta-band activity during pre- interview phases and alpha-band activity during the deception task, particularly in left temporal regions, compared to non-deception group (NDG; N=15). While IBS increased during deception, the DG showed reduced heart rate coordination across all experimental phases. These findings support the conceptualization of deception as an interpersonal process which requires substantial cognitive resources. The results underscore the value of hyperscanning methodologies for detecting deception's dyadic signatures and advocate for integrating second-person neuroscience approaches into forensic paradigms.