Fig. 7. Search density plots for experiments in which the ants were trained to locate the nest in the centre of a four-cylinder square array of landmarks (open circles in inset). Search densities recorded during 3-min periods are given for data from all release sites combined (All) as well as separately for different release sites (N, E, S, W). The density of search activity is given as a percentage for each 20 cmx20 cm square pixel (N=225 squares) within the four-landmark array. The inset shows the configuration of landmarks (open circles) and release sites (stars) used during training and testing. N, nest.