Figure 1.

Theoretical illustrations of Morris Water Maze strategies. When latency is the only measure of performance in the MWM, the improvement between trials 1 and 2 (directly below) would be interpreted as successful learning in A with impairments in B and C, and no learning whatsoever in D. If distance is considered, B now shows equivalent learning to A, C appears somewhat impaired, and D shows no evidence of learning. If the route is examined it is obvious that A and B are using spatial cues to move directly towards the platform while neither C nor D use these spatial cues. Nonetheless, C shows clear learning by a non-spatial strategy (thigmotaxis). Examination of the probe trial data that would have resulted from the removal of the hidden platform, reveals that only A and B know where the platform is relative to spatial cues while C and D are indistinguishable in they both visit all quadrants equally. Only examination of all four of these parameters give the full picture of how the animals behave in the maze. Most studies have used only latency. Those using distance, route and/or probe trials have shown evidence for strategies B and C. No studies, to our knowledge, have shown evidence for D (see table 1 for details).