Fig. 1. Schematic view of the experimental setup. Training took place in a 10 m channel with an exit hole on the side, where ants were able to enter and leave the setup and forage to a feeder 9 m down the channel. The coloured rectangular area denotes the position of the ground landmark during training (PI-position). For tests, the ants were transferred into another channel 18 m long and aligned parallel to the training channel. Within this test channel ants were presented with a ground landmark at varying positions (LM-position) relative to the position indicated by their path integrator (PI-position, experiment 1), or with ground landmarks differing from the training landmark in visual or tactile properties (experiment 2). The first six U-turns of the ant's search behaviour were recorded. Drawings are not to scale.