A cautionary note on interpreting the effects of partial reinforcement on place learning performance in the water maze.

The effects of partial reinforcement on dry land and swimming pool place learning tasks have recently been compared and it has been suggested that they differ fundamentally [8]. That is, partial reinforcement impairs performance in the water maze, but not on dry land. However, other evidence suggests that partial reinforcement may have the opposite effect in the water maze, strengthening the accuracy and persistence of spatial responses. We discuss how the discrepancy may depend on 'levels' of negative reinforcement (e.g. escaping to a submerged platform before complete removal from the pool) and how experimental procedures may set up competitive contingencies that reinforce alternative behaviors. Finally, we consider data from past lesion studies and suggest ways to improve the design of future water maze experiments.