Question of "head preference" in response to worm-like dummies during prey-capture of toads, Bufo bufo

If a black worm-like dummy is moving against a white background, toads fixate and snap at the leading end of the stimulus. This "head preference" phenomenon is - within limits - independent of (i) background structure, and (ii) stripe length. "Head preference" can be disturbed by reducing the amount of the stimulus background contrast as well as by point structures incorporated in the worm-like shape of the stimulus. If the stimulus-background contrast of the worm dummy is reversed, toads exhibit a clear preference in fixating and snapping for the trailing end of the stimulus. This "tail preference" is independent of changes in (i) and (ii). The neural basis of "head preference" or "tail preference" respectively, is discussed.