Fig. 1. Routes taken by experienced ants along the wall. Top: sketch of the arena and wall. (A,C,E) Mean path from start (S) to food (F), with 95% confidence intervals, for the 20 cm, 30 cm and oblique training routes respectively (20 cm route, n=154, N=17; 30 cm route, n=65, N=6; oblique route, n=88, N=6; incompletely recorded paths are excluded. n, number of trajectories; N, number of ants). The mean path was calculated by averaging, over all runs, the perpendicular distance from the wall (y) at 10 cm intervals along the wall (x). (B,D,F) Trajectories from three different ants performing the 20 cm, 30 cm and oblique routes respectively. Data are rotated to align the wall positions. (G) The arena was divided into six sectors, and runs from all conditions were separated into six groups depending on which sector contained the wall. To test whether ants behave uniformly within the arena, we assessed the quality of each run by determining how much each trajectory strayed from the direct route to the goal. This metric, referred to as normalised error, is defined as the mean difference in y value between the actual route and the direct route, normalised by the y value for the direct route. There are no significant differences between the six groups (one-way ANOVA, F=0.391, d.f.=5,286, P=0.86). (H) There is also no significant clustering of bad trajectories. Bad trajectories are defined as those that fall more than 2 S.D. from the mean, for straightness (Sinuosity; outer circle) or mean distance from the wall (Mean y; inner circle). Neither distribution differed significantly from random (Rayleigh test; mean distance from wall, r=0.18, P>0.3; straightness, r=0.18, P>0.3).

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