Positional choices and visual discrimination in non-delayed appetitive discrimination tasks in mice.

Mice were submitted to visual discrimination learning using a large choice compartment positioned in front of two adjacent runways, black and white, one of which was baited. Rate of acquisition, expressed by the mean number of sessions to criterion did not differ between the initial task and two reversals. However, the number of correct choices before criterion was significantly lower on both reversals compared to original learning. Position habit rates did not vary significantly between acquisitions, and they were negatively correlated with visual discrimination rates in the three learning phases. This observation, and the fact that on each phase, position habits were largely absent on initial sessions and only developed gradually, suggest that position habits may occur when animals do not grasp the solution to the visual task.