Fig. 5. Mean flight velocities at various rotational velocities of the flight arena. Mean horizontal (black, left scale), turning (blue, right scale) and vertical (red, left scale) velocity of the animals in response to the changes in stimulus conditions. The fly may fully achieve retinal slip compensation (grey area) when angular velocity, which is the rate of change in gaze, is equal to the angular speed of the rotating environment at a given horizontal velocity (slope=1, dotted blue). Positive turning and vertical values mean counter-clockwise turns and climbing flight, respectively; N=22 (0° s^–1), 23 (100° s^–1), 20 (300° s^–1), 20 (500° s^–1), 21 (700° s^–1) and 26 flies (900° s^–1). Means ± s.e.m.