Marble burying had predictive validity for anxiolytic drugs and some have proposed it as a model of OCD. Mice are placed individually in clean mouse cages containing 5-cm of hard wood bedding. Marbles are placed in each cage in evenly spaced rows. When exposed to foreign objects in their enclosure (such as marbles) mice tend to bury them. Mice pretreated with anxiolytic agents show less marble burying compared to the control mice.