Behavioral synchronization of two individuals during cooperative interaction: the role of the mentalization ability as measured by the reading the mind in the eyes test.

Background: Interpersonally synchronized behaviors play a fundamental role in social interactions. An important prereqvisite for behavioral synchronization is the mentalization ability of the individuals involved in the interaction. While the Reading the Mind in the Eyes Test (RMET) is widely applied to measure mentalization, most studies of RMET used single-subject designs, which lack ecological validity and have limited generalizability for real, on-going, reciprocal social interactions. Using a two-subject design, our objectives were to examine (i) the predictive validity of RMET for the synchronous behavior of two interacting individuals during a reaction time task; (ii) the association of age-related RMET performance with interpersonal coordination; and (iii) the influence of various potentially important covariates on the association, including psychological distress, basic personality domains such as impulsive responding, and lack of attention.

Methods: We investigated 24 dyads, using 48 subjects (mean age 32.9 [SD = 12.8] years). Synchronous behavior was indexed by the correlation of participants' responses in terms of reaction times (RTs) to visual stimuli. We used the correct recognition rate from the RMET as a measure of mentalization ability.

Results: Our results indicated that the synchronization of the behavioral responses (i.e., RTs) between the interacting pairs and their mentalization ability, as measured by the RMET, showed significant association. Specifically, with good performance (100% correct recognition), the behavioral response synchronization was significantly (F = 153.34, p < 0.0001) higher (Pearson correlation, r = 0.41) than with poor performance (50% correct recognition, r = 0.25). Higher age was inversely related to behavioral synchronization, with no interaction (p > 0.1) with RMET performance). The inclusion of additional covariates (e.g., measures for psychological distress and basic personality domains) in the analyses did not alter the significance of the association between RMET performance and behavioral synchronization (p < 0.05, after adjustment).

Conclusions: Our results confirm the utility of RMET, as a measure of mentalization, to predict participants' ability to achieve behavioral synchronization during cooperative interaction. These results may facilitate research into mental disorders, where problems with social interactions play a role in symptom presentation. For this purpose, future studies with larger sample size should examine whether our findings can be dimensionally extrapolated to patients with such disorders.