Fig. 6. Velocity profiles of forward movement of the body overground during a time window of 6 s at the beginning of the gap-crossing sequence. (A) t=0 (broken line) taken as initial `non-contact' of the front leg (tarsus crosses footbridge level while swinging into the gap for the first time); (B) same data as in A, but t=0 (broken line) taken as initial `non-contact' of the antenna. Heavy lines, arithmetic mean; thin lines, single trials; red dots in the upper panel mark `non-contacts' of the antenna (t=0 in B), illustrating their temporal relation to corresponding `non-contacts' of the front leg. Left, 30 mm trials; right, 50 mm trials; N=7 trials in each gap width, bin width=200 ms.