Fig. 6. (A) Experiment 4 – effect of pattern texture on flight speed. Comparison of mean flight speeds when the walls are lined with vertical sinusoidal gratings of spatial period 1.8 cm, 3.6 cm or 7.2 cm. (B) Experiment 5 – effect of pattern contrast on flight speed. Comparison of mean flight speeds when the walls are lined with vertical square-wave gratings of contrast 0%, 10%, 30%, 50%, 70% or 100%. (C) Experiment 6 – comparison of mean flight speeds when the walls are lined with vertical stripes (producing strong optic flow cues) or axial stripes (producing very weak optic flow cues). Other details are as in Fig. 3.