Fig. 4. (A) Search density distribution and (B) differential search density distribution of the ants' nest search behaviour exhibited under different test conditions. All ants were trained with a landmark (black square) directly by the nest and tested with a displaced landmark (coloured square). Test 1A: LM-position was identical to the one in the training situation: 9 m (black line and square). Test 1B: LM-position, 7.5 m (red line and square). Test 1C: LM-position, 6 m (blue line and square). Test 1D: LM-position, 2 m (green line and square). Control 2: no landmark present during test. Note: in B the data of control 2 (in A) were subtracted from each of the other data sets for display reasons.