Fig. 9. Response of Drosophila (blue) to a velocity bias on two random-dot backgrounds at different dampings. Amplitude response (left-minus-right) to a low- (A; pattern shown in Fig. 1C) and high-contrast panorama (B; pattern shown in Fig. 1D). (C) Mean values of panorama velocity and (D) mean relative amplitude difference, both plotted as a function of frictional damping coefficient. Data are mean values of entire flight sequences using low- (red) and high (blue) contrast pattern and during object orientation behaviour (black). Grey area indicates threshold range of the visual system (cf. Materials and methods). For more details, see legend to Fig. 4. Values are means ± s.e.m., N=24 (black), N=8 (red), and N=15 flies (blue).