Fig. 3. Temporal frequency tuning curves for expansion and rotation optomotor responses. Responses to different spatial wavelengths are pooled. Values are means ± s.e.m. for N=36 flies. A Gaussian waveform (to facilitate visual comparison only) is plotted in both panels and is shifted downward 20% for the rotation plot. Maximum WBA (R/R_max) refers to the peak left minus right wingbeat amplitude response (R), divided by the maximum response in the trial (R_max).