<p>Roach collision-based antennal steering.</p>

(Some of the “points” are actually clusters of individual time points for intervals during which the roach paused to make directional decisions.) The walls and obstacles of the enclosure have been plotted in black for reference. Green boxes surround the points preceding major directional changes, and corresponding insets show how, in each case, its change in direction is precipitated by a collision of one of its antennae with a wall or obstacle.

The collisions are marked with a red line for emphasis. In the upper-left inset, a dashed red line indicates a secondary antennal collision that occurred very shortly after another (solid red line). The final trajectory deflection that can be seen shortly before the far-right end of the enclosure (not shown in an inset) was likely caused by an antennal collision with a drop of water on the floor of the enclosure.</p>