Fig. 5. Flies maintain better closed-loop control of an expansion/contraction pattern than a full-field rotatory pattern. The fly controls the direction and velocity of either a full-field rotational (A) or a lateral expansion/contraction pattern (B) by adjusting the difference between left and right wing stroke amplitude. (C) The fly's ability to hold the pattern steady is reflected by the variance in the position over a series of 1 s windows. (D) A sinusoidal bias is added to the feedback signal to challenge the fly's ability to control the pattern. The variance in position is much larger when the fly controls the position of a rotational pattern when compared to the expansion/contraction pattern.