Fig. 4. Retinal position of real and imaginary cylinder during a trajectory. (A) The horizontal path of the centre and of the left and right edges of the bottom of the cylinder across the retina is shown as the ant moves from the start to a point 80 cm away. Estimated horizontal, retinal position for a stated distance comes from the mean retinal position of all data (194 trajectories from 20 ants) within the interval 4 cm either side of the stated distance. (B) Imaginary retinal positions for tests with no cylinder present (71 trajectories from eight ants). (C) The distribution of retinal positions of the centre of the cylinder accumulated over the first 45 cm of the route. Left panel: trajectories with cylinder present (194 trajectories from 20 ants). Right panel: imaginary retinal positions in tests without a cylinder (71 trajectories from eight ants). (D) Distribution of retinal positions of the right edge of the landmark over the second 45 cm of the route. Left panel: trajectories with cylinder present. Right panel: imaginary retinal positions in tests without a cylinder. Data from ants trained with the cylinder on the left or right are combined and represented as though the cylinder is on the left.