Animals typically learn to solve decision tasks in the laboratory through trial and error, rather than through explicit instruction of decision rules. The decision rule used by the animal may be difficult to read out directly from choice or accuracy data, when multiple decision rules are possible given the task design. Here, we demonstrate that in rats performing a visual decision task, probe stimuli can be used to gain information about decision strategy, and in our task revealed variation in the decision strategies used across rats. Further, we find that in a more general version of this task, rats use varying decision strategies that differ from the optimal ideal observer strategy, but respond to manipulations of the stimulus distribution by adjusting their behavioral strategy. Therefore, we show that informative probe stimuli can be used in both training and testing to confirm and shape behavioral strategy in a perceptual decision task.