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The ability of desert locusts, Schistocerca gregaria, to separate pattern flow within the lateral visual fields into its rotatory and translatory components was studied in tethered flight under open-loop conditions. The optomotor turning behavior results from the sum of compensatory steering and upwind/downwind turning induced by the rotatory and translatory component of pattern flow, respectively, Thereby, the analysis of the visual stimulus is supposedly achieved by linear binocular interaction, i.e., by summation and subtraction of the optomotor effectiveness of the pattern flow on. either side, Our results indicate that, in addition, locusts take into account the relative contribution of the rotatory and the translatory stimulus component to the sum total of pattern flow. This yields a factor which modifies the gain of the control loop of either of the response components to give a nonlinear response. It results in a weakening of the behavior upon stimuli composed of rotatory and translatory components. We discuss our results as an adaptation by which an animal avoids inappropriate behavior upon ambiguous stimulus situations.