Résumé
Theoretical models posit that teamwork, the social interaction in which individuals collaborate to reach a common goal, matures and progresses during a task episode. Due to the limitations of the traditional psychological tools (i.e. questionnaires), this evolution of teamwork has never been verified. As inter-brain synchrony (IBS), the degree of similarity between individuals' brain activity, appears to be a relevant measure of teamwork, we used IBS to examine its trajectories during a task episode. We hypothesised that IBS would increase over time. Forty dyads completed a 30-minute cooperative task with asymmetric roles. fNIRS hyperscanning recorded brain activity in six regions within the prefrontal and temporoparietal areas. IBS was quantified using wavelet transform coherence. Linear mixed models, with time as a fixed effect, slope and intercept as random effects for dyads tested the effect of time on IBS. Control analyses using permuted dyads confirmed IBS appearance during teamwork. No significant effect of time on IBS was found; however, there was significant heterogeneity in IBS trajectories between teams. There is no overall increase or decrease in IBS in the sample. Further research is needed to understand why some teams show an increase in IBS over time, while others show a decrease.