Social effects on spatial choice in the radial arm maze.

Social memory was investigated in the context of a spatial working memory task. Pairs of rats were tested in an eight-arm radial maze. Under most conditions, there was a tendency to choose maze locations that had been visited earlier by the other rat. The possibility that this tendency is produced by common preferences for particular maze locations was ruled out. An opposite tendency to avoid visits to locations that had been visited earlier during the trial by another rat was found only when the maze location contained two pellets (rather than an undepletable supply), the rats' ability to see each other in the maze was restricted to the central arena, and the maze location had been previously visited by the focal rat. The amount of food available in maze locations did not otherwise modulate social influences on spatial choice. The results indicate that memory for a rat's own previous choices is combined with memory for the choices made by another rat.