Fig. 5. (A) Amount of time for large and small fish to find the aperture with different landmark sizes. The control fish had no landmarks so they were not included. Data represent the mean time ± S.E.M. of each group for the first 3 min of trial-day 10 (medium landmark size; 6.8 cm) and the first 3 min after the landmark either increased (to 8.3 cm) or decreased (to 3.9 cm) in size. Both the large and small fish increased the amount of time to find the aperture after the landmark size increased. When the landmark size decreased, the large fish did not change the amount of time to find the aperture, the small fish took longer. (B) Height at which large and small fish made contact with the divider wall in the presence of different sized landmarks. Data represent the mean height ± S.E.M. that each group made contact with the divider wall in the first 3 min of trial-day 10 (medium landmark size) and the first 3 min after the landmark increased or decreased in size. The height of the aperture (25.5 cm above the aquarium floor) is marked. (C) Mean number of times per trial-day that fish crossed from one compartment to the other for the first 3 min of trial-day 10 (medium landmark size) and the first 3 min after the landmark increased or decreased in size. Both the large and small fish decreased the number of times that they crossed through the aperture after the landmark changed size.