Figure 1.

Schematic diagram of the swimming pool tasks run in either a plain rectangle (Experiment 1) or a square with different patterned walls (Experiments 2, 3). The inner shape depicts the pool, the surrounding circle is the larger pool within which the smaller pool is placed, and the rippled circle represents the curtains used to block distal cues. Each inner pool was rotated on consecutive trials, as indicated in the figure. For the square pool the thick dark lines represent black walls (Experiment 2), whereas the broken lines represent striped walls (Experiment 3). In Experiment 3 the rats received an additional probe in which the wall configuration was changed from one striped wall to two, adjacent striped walls (1D). The small circle represents the platform where a rat would be placed passively. The small dotted circle represents the other identical and, hence, other correct corner.