Fig. 4. Summary of the data set used in the analysis for all experiments in which the extended dummy track intersected the vertical line defined by the crab's home vector on the crab side of the burrow (crab side = 1; see inset in B). Consecutive dummy positions are shown in a coordinate system defined by the crab's home vector. The data from different experiments were moved and rotated such that the crab's home vector always points vertically down towards the burrow, which was placed at the centre of each panel (grey circle). The trajectory of the dummy is shown from the moment it became visible in the recording area until the crab responded to the dummy or until the dummy reached it's closest point to the burrow. The thick, vertical, black line above the burrow shows the range of crab starting positions for all the experiments accumulated in the respective panel. (A-C) All trials in which the crabs responded to the dummy; (D-F) all trials in which the crabs did not respond to the dummy, or where they responded late, after the dummy had reached its closest approach to the burrow. The three rows of panels sort the dummy presentations according to the crab-burrow distance, with increasing distance from top to bottom (A,D: 5-15 cm; B,E: 15-25 cm; C,F: 25-55 cm). The position of the dummy at the time a crab responded has been marked by an enlarged symbol: a dot indicates that the response occurred on the dummy's first approach, a square indicates that the crab responded after the dummy changed direction at the end of its track and was moving back towards its starting position. In addition, a black symbol indicates that the crab responded while the dummy was approaching the burrow, whereas a grey symbol indicates that the dummy was moving away from the burrow when the response occurred. As the tracks are only shown up to their closest point to the burrow, some of the dots and squares do not lie directly on the printed section of a path in panels D, E and F. All tracks are shown to move from right to left to increase the clarity of the figure. To achieve this, tracks were mirrored at the vertical home vector where necessary.

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