Fig. 1. Experimental arrangement: the training (left) and test (right) situations. Ant foragers that have left the nest (N) and have walked straight to an artificial feeder (F) are captured at F and displaced to the test area. Upon release at R, they immediately head off in their home direction. During their homebound runs, they have to pass through a 4 m long and 1.5 m wide experimental channel. Having arrived at the fictive position of the nest (N*), they are returned to N. The visual patterns on the inner sides of the walls forming the channel and/or the heights of the walls can be varied independently on the left and right sides of the channel. At the entrance to the channel, a funnel formed by two narrow plates serves to guide the ants into the channel.
