Acquisition of the standard Morris water escape task by four rat strains. The platform escape latencies (s; panel a), distance traveled to reach the platform (cm; panel b), swimming speed (cm.s-1; panel c), and the distance to platform (cm; panel d) are depicted. Performance of the four strains in the probe trial: the time spent in annuli (s; panel e) and quadrants (s; panel g), and the distance swum in annuli (cm; panel f) and quadrants (cm; panel h) are depicted. The means and standard errors of the means are shown. The lower left panel shows the quadrants, annuli, and the platform position during acquisition of the task.