Anxiety & Experimental Performance

It could be argued that as long as the handling technique is consistent, the anxiety induced by improper handling will constitute a controlled variable, and hence will not skew experiment results. However, this counterpoint misses several key issues, such as the fact that researchers who have not seriously considered the deleterious effects of their handling technique on mouse behaviour are unlikely to have taken steps to develop a consistent handling protocol.

Other issues include the need to be able to compare results between different batches of mice, different experiments, and different research groups and institutions. Scientific research is not considered good and reliable if it cannot be replicated by independent researchers; lack of consideration for handling technique could prevent successful replication and cast doubt on the validity of a large body of otherwise valuable scientific work.[1]

Scientists have noted a few ways that anxiety could affect mouse performance in particular kinds of experiment. Heightened anxiety reduces focus, and will make it harder for mice to react appropriately to a stimulus of interest, like the urine of another mouse. Tasks that require learning, memory, and problem solving (such as the frequently used T maze) will become more difficult. Motivation to explore and move around could be reduced, affecting performance in paradigms such as the elevated plus maze, open field, light-dark box, and forced swim test . [1]

With the open field test for example, while improper handling might not affect the test’s ability to assess overall anxiety level, it will prevent researchers from assessing the reaction of the mice to a particular stimulus, on account of the reduction in focus in highly anxious mice.[1]

It is clear then that confounding effects of improper handling cannot be ignored, and that a detailed consideration of handling optimisation is necessary.