Fig. 3. Search distributions for an absent feeder that is normally placed between two cylinders. Starting pen was 70 cm from the feeder. (A) Tests with training cylinders of equal size. (B) Tests with two smaller cylinders. The darkest area represents 18.98% of the search in the training condition (N=41 paths) and 4.32% in the test condition (N=42 paths). (C,D) Search distribution with small cylinders, when ants were fixating within ±20° of the centre of one or other cylinder, as shown by the schematic ant above each distribution. The mean X positions of the two distributions differ significantly (Student's t-test; P=0.005, t=2.91, d.f.=72).