Author response image 1. Deviation from the final improvement as a function of the time during the trial for every individual (denoted by a different colour) in all twos (left panels) and fours (right panels) recruited in our study.

The rates of convergence to the final improvement differs somewhat between different groups, but it was highly correlated between individuals of the same group. As such, it is difficult to isolate the contribution of a specific individual to the improvement of a collective, and so each group of twos and fours must be treated as a random factor in the analysis.