Fig. 3. Trajectories with displaced start position. Ants with no cylinder present were started from the normal position or 30 cm to its left (near) or to its right (far). Arrows show mean trajectory directions measured at 20 cm, 40 cm, 60 cm and 80 cm from the start. Trajectories within a start condition are sufficiently similar that r, the mean vector length, is greater than 0.9 at 20 cm, 40 cm, 60 cm and 80 cm from the start. The open circle indicates the normal position of the absent cylinder. The three triangles represent the areas enclosed by extending the three headings at 40 cm, 60 cm and 80 cm.