Fig. 3. (A) Results from experiments in which the gratings presented on the left and the right walls are stationary, but the spatial period of the right-hand grating (=42.9°) is twice that of the left-hand grating. N=26. (B) The left-hand grating is moved at a speed of 0.1 m s^–1 in the same direction as the ant’s direction of motion (left) or at a speed of 0.2 m s^–1 in the direction opposite to the ant’s direction of motion (right). The right-hand grating has the same spatial period (=22.3°) but is stationary. Open arrow, direction of pattern motion. Red line, midline of channel. Green line, position at which the speeds of image motion experienced by the ant’s two eyes are balanced. N=30. For further conventions, see Fig. 2A.