Figure 2. Comparison of ball motion in dyed and undyed flies.

(a) Histogram of normalized forward running speeds (ball pitch) from 2-h trials for normally dyed flies with the HeNe laser on (grey, n=27) and undyed flies with the HeNe laser off (black, n=3). Red indicates the median of dyed flies. (b) Histogram of intervals between peaks of forward running (ball pitch). Experiments and plot colouring as in a. (c) Auto-correlation plots for ball pitch vectors. Experiments and plot colouring as in a.