Altshuler and coworkers were able to reproduce their symmetry-breaking experiments previously done in ants in humans, using a simplified version of the theoretical model proposed earlier by Helbing et al. based on the fact that walkers tend to follow the general direction of motion of their neighbors (" Vicsek's rule "), and such herd behavior increases as the so-called "panic parameter" increases. In the case of ants, the panic parameter is supposed to be low when no repellent is used and high when the repellent is used.