Following the coding scheme of Darses et al., developed for the analysis and modeling of cognitive activities of collective design, the content of each unit was coded according to its type (query or assertion), the associated cognitive activity (generation, evaluation, information) and the subject concerned (data, solution, object, goal, procedure, task). Table defines each of these categories. Then, and as recommended by Corroyer and Wolff to estimate the magnitude of the association between two categorical variables, we used Cramer's V2 and Relative Deviation (RD), as in other studies. Cramer's V2 lies between 0 and 1. The association is conventionally considered as strong when Cramer's V2 > 0.16, as weak when Cramer's V2 < 0.04, and as intermediate between the two scores. The RD is calculated on the basis of a comparison between observed and expected frequencies (i.e., those that would have been obtained if there was no association between the two variables). There is attraction when RD is positive, and repulsion when it is negative. By convention, we retain only RD with absolute terms > 0.25.