The use of a test battery assessing affective behavior in rats: Order effects

Many studies have used test batteries for the evaluation of affective behavior in rodents. This has the advantage that treatment effects can be examined on different aspects of the affective domain. However, the behavior in one test may affect the behavior in following test. The present study examined possible order effects in rats that were tested in three different tests: Open Field (OF), Zero Maze (ZM) and Forced Swim Test (FST). The data of the present study indicated that the behavior in ZM was the least affected by the order of testing. In contrast, the behavior in the FST (and to a less extend the OF) was dependent on the order of the test in the test battery. Repeated testing in the same test did not change the behavior in the ZM. However, the behavior in the OF and FST changed with repeated testing. The present study indicates that the performance of rats in a test can be dependent on the order in a test battery. Consequently, these data caution the interpretation of treatment effects in studies in which test batteries are used.

► Test batteries are used to examine the affective behavior of rats.
► The order of a test in a test battery could affect the behavior in subsequent test.
► This study shows that the Zero Maze is robust to order effects and that the Forced Swim Test is affected by testing order.