*2.4. Video Segmentation*

For each video, the sequences corresponding to the 4 narrative themes (Nt, Tr, Pr, Prd) were identified and manually marked by 2 independent judges using the Boris software [65]. In order to compute the inter-rater reliability, the Cohen's *κ* was evaluated within a 2slong sliding window. We obtained values of *κ* = 0.83, and *κ* = 0.86 for video M and R, respectively, corresponding to a strong agreemen<sup>t</sup> [66]. Onsets and durations of the themes were built as the intersection between the chunks identified by the two raters. Finally, the onsets and the durations of both the EYC and BSL epochs, as well as the 4 themes, were exported for the subsequent analyses.
