The influence of excitatory and inhibitory landmarks on choice in environments with a distinctive shape.

In two experiments rats were trained to find one of two submerged platforms that were located in diagonally opposite corners-the correct corners-of a rectangular pool. Additional training was given to endow two different landmarks with excitatory and inhibitory properties, by using them to indicate where a platform was or was not located in either a rectangular (Experiment 1) or a square pool (Experiment 2). Subsequent test trials, with the platforms removed from the pool, revealed that placing the excitatory landmark in each of the four corners of the rectangle resulted in more time being spent in the correct corners than when the four corners contained inhibitory landmarks. This result is contrary to predictions derived from a choice rule for spatial behavior proposed by Miller and Shettleworth (2007).