Fig. 3. Drosophila optomotor behavior. (A) Average response of eight (except for 5°, where N=4) individuals to six different spatial wavelengths. Positive values indicate head deflections with the direction of the pattern, and negative values indicate deflections in the reverse direction. (B) For each wavelength the cumulative, normalized, mean of the last 3 s is indicated by a circle ± s.e.m. bars. The solid line is the best-fitting EMD model, with mean sampling bases of 4.8° and 4.9° with s.d. of 0.1° for both, acceptance angle of 7°, and a bias B of 1.02 towards the smaller sampling base. Numbers indicate sample sizes for each spatial wavelength.