In light of the hotly discussed ‘reproducibility crisis’, a rethinking of current methodologies appears essential. Implementing multi-laboratory designs has been shown to enhance the external validity and hence the reproducibility of findings from animal research. We here aimed at proposing a new experimental strategy that transfers this logic into a single-laboratory setting. We systematically introduced heterogeneity into our study population by splitting an experiment into several ‘mini-experiments’ spread over different time points a few weeks apart. We hypothesised to observe improved reproducibility in such a ‘mini-experiment’ design in comparison to a conventionally standardised design, according to which all animals are tested at one specific point in time. By comparing both designs across independent replicates, we could indeed show that the use of such a ‘mini-experiment’ design improved the reproducibility and accurate detection of exemplary treatment effects (behavioural and physiological differences between four mouse strains) in about half of all investigated strain comparisons. Thus, we successfully implemented and empirically validated an easy-to-handle strategy to tackle poor reproducibility in single-laboratory studies. Since other experiments within different life science disciplines share the main characteristics with the investigation reported here, these studies are likely to also benefit from this approach.

The ongoing debate on the reproducibility crisis in the life sciences highlights the need for a rethinking of current methodologies. Since the trend towards ever more standardised experiments is at risk of causing highly idiosyncratic results, an alternative approach has been suggested to improve the robustness of findings, particularly from animal experiments. This concept, referred to as “systematic heterogenisation”, postulates increased external validity and hence, improved reproducibility by introducing variation systematically into a single experiment. However, the implementation of this concept in practice requires the identification of suitable heterogenisation factors. Here we show that the time of day at which experiments are conducted has a significant impact on the reproducibility of behavioural differences between two mouse strains, C57BL/6J and DBA/2N. Specifically, we found remarkably varying strain effects on anxiety, exploration, and learning, depending on the testing time, i.e. morning, noon or afternoon. In a follow-up simulation approach, we demonstrate that the systematic inclusion of two different testing times significantly improved reproducibility between replicate experiments. Our results emphasise the potential of time as an effective and easy-to-handle heterogenisation factor for single-laboratory studies. Its systematic variation likely improves reproducibility of research findings and hence contributes to a fundamental issue of experimental design and conduct in laboratory animal science.

The 3R principles provide an ethical framework for animal research throughout the world. However, despite the increasing awareness of these principles, there is still a lot of room for improving their implementation, especially when it comes to reduction. By combining Bayesian statistics with a shift in experimental design, here we present an entirely new idea to reduce animal numbers within experiments.

Automated Home-Cage Testing as a Tool to Improve Reproducibility of Behavioral Research?

What are social niches, and how do they arise and change? Our first goal in the present article is to clarify the concept of an individualized social niche and to distinguish it from related concepts, such as a social environment and a social role. We argue that focal individuals are integral parts of individualized social niches and that social interactions with conspecifics are further core elements of social niches. Our second goal in the present article is to characterize three types of processes—social niche construction, conformance, and choice (social NC³ processes)—that explain how individualized social niches originate and change. Our approach brings together studies of behavior, ecology, and evolution and integrates social niches into the broader concept of an individualized ecological niche. We show how clarifying the concept of a social niche and recognizing the differences between the three social NC³ processes enhance and stimulate empirical research.