The probabilities P++, P+o and P+o for wild type flies along the boundary of two circular arenas of radii 4.2 cm and 2.5 cm are shown. P++, P+o and P+o are shown in panels A, B and C, respectively as a function of time. Simulations were performed on the circular arena of radius 4.2 cm using the parameters estimated from 2.5 cm arena. P++, P+o and P+o obtained from the simulations and experiments (both from 4.2 cm arena) are also shown. There were no statistical differences between the experiments and the simulations in the behaviors of directional persistence (P++ : p = 0.7308, F(2,594) = 0.314; P+o : p = 0.892, F(2,594) = 0.115; P+− : p = 0.128, F(2,594) = 2.060).