The relative influence of place and direction in the Morris water task

The present study evaluated the generality of directional responding (Hamilton, Akers, Weisend, & Sutherland, 2007) in the Morris water task and attempted to identify methods that would yield a preference for navigation to the precise spatial location of an escape platform in the room. Four experiments evaluated the effects of training with the pool in a fixed location by repositioning the pool for a no-platform probe trial such that the absolute spatial location of the platform and the relative location of the platform within the pool (to which a directional response would occur) were in opposite quadrants. Two experiments attempted to explicitly train navigation to an absolute location in the room by repositioning the pool during training while keeping the platform at the same location in the room. A preference for directional responding over navigation to the precise location of the platform was observed across a wide range of conditions including when rats were given extensive training (240 trials; Experiment 1), only given platform placement experience in the absence of active swim training (Experiment 2), trained to navigate to multiple platform locations in a moving platform variant of the task (Experiment 3), and when animals were trained to navigate to a particular location regardless of the position of the apparatus in the room (Experiments 4 - 5). A preference for navigation to the absolute spatial location of the platform was observed only when the salience of the pool was reduced by filling it to the top with water (Experiment 6)