Fig. 8. Speed vs steadiness. (A) Time courses of center of mass (COM) speed shown for individual flies. Time courses are aligned so that lift-off occurred at 0 ms, and individual time courses end when the fly left the field of view of our cameras. The bar plot at the right indicates the COM speed (mean ± s.e.m.) for all flies over the first 2 ms of flight (grey region). (B) Time courses for steadiness (S) shown for individual flies. Steadiness was calculated from angular speed as described in the text, with large S-values corresponding to low angular speeds. Bar plots show steadiness (mean ± s.e.m.) over the first 2 ms of flight as in A. Voluntary (Vol.) trials are shown in blue, escape (Esc.) trials in red. Mean COM speed and steadiness are significantly different between voluntary and escape conditions, P0.001, ANOVA.