APA Dictionary of Psychology

an apparatus used as a test of anxiety in laboratory rats and mice. It is a cross-shaped maze that is raised from the ground and has two enclosed arms and two open arms. Because of a natural fear of heights, rodents typically spend more time in the enclosed arms than in the open arms. However, if injected with anxiolytic (antianxiety) drugs, rodents will increase the amount of time they spend in the open arms.