Influence of a beacon on spatial learning based on the shape of the test environment

In 5 experiments rats were required to escape from a triangular shaped pool by swimming to a submerged platform. The principal group of interest in ea ch experiment received training with a beacon attached to the platform. The purpose of the experiments was to assess if the beacon overshadowed (Exper iments 1-4) or blocked (Experiment 5) learning about the position of the pl atform with reference to the shape of the pool. The platform was located in the center of the pool for the first 2 experiments and in a corner for the remaining experiments. Although there was an overshadowing effect in Exper iment 1, the remaining experiments failed to reveal any disruptive influenc e of the beacon on learning based on the shape of the pool. Moreover, in Ex periments 3-5 there was an indication that the beacon facilitated such lear ning. The results suggest that spatial learning based on the shape of a tes t environment may not take place in the same way as that based on more disc rete landmarks.