A team from the Royal Academy of Music and the University of Birmingham found that analysing how individual musicians vary their timing to follow the rest of the group can indicate a hierarchy.
They say it shows some quartets have a clear leader to ensure perfect harmony.
However, in other "democratic" quartets the musicians all follow each other, playing an equal role.
Prof Alan Wing, from the University of Birmingham, UK, said of the study, published in the Journal of the Royal Society Interface: "In one quartet, it was as if there was an autocracy. In the other, it was more like a democracy."
The subtle interactions within a string quartet can bring a performance to life, but the team says it is this interplay that reveals..........