Fig. 4. Xenos peckii optomotor behavior. (A) Average responses of all tested individuals to 12 different spatial wavelengths. As in Fig. 3, positive values indicate head movements following the direction of the pattern, and negative values indicate head movements in reverse direction. (B) Examples of three normalized, average responses of the last 3 s to each wavelength. Although details of the curves vary, each of them is characterized by a local maximum between 18° and 24° (arrow). (C) For each wavelength the cumulative normalized response of the last 3 s of all individuals is indicated by a circle ± s.e.m. The number of individuals that were tested for each of the points are indicated.