  Social interaction increases significantly the performance of a wide range of
cooperative systems. However, evidence that natural swarms limit the number of
social connections suggests potentially detrimental consequences of excessive
social activity. Using a canonical model of collective motion, we find that the
responsiveness of a swarm to local perturbations is reduced when the social
interaction exceeds a certain threshold. We uncover a similar effect for two
distinct collective decision-making models of distributed consensus operating
over a range of static networks. While increasing the amount of interaction
always increases the capacity of these systems to adapt to slow changes, an
excess of social behavior can hinder the swiftness of their response to fast
perturbations. These results have far-reaching implications for the design of
artificial swarms or interaction networks.
