Inhibitory control tests in non-human animals: validity, reliability, and perspectives

Inhibitory control, the ability to control impulsive or pre-learned behaviour in order to reach a more rewarding goal, is essential in many aspects of normal life. In non-human animals, better inhibitory control performances have been associated with a larger brain, better problem-solving skills, and fitness benefits. This crucial cognitive ability has been studied in a wide range of fields (psychology, neurosciences, animal cognition) and has been tested in several animal classes from insects to mammals. Unfortunately, unlike in human test psychology, the common paradigms designed to measure inhibitory control in non-human animals often suffer from a lack of validity and reliability and have yielded mixed results. Therefore, the nature of inhibitory control, either defined as a common ability or a suite of distinct processes, is still debated. Besides, the evolutionary processes shaping the variation in inhibitory control, often tested using a single task, are still poorly understood and the relative influences of ecological, anatomical or social factors as evolutionary drivers of this ability remain unclear. Finally, it is only recently that researchers have focused efforts on the factors necessary for the evolution of inhibitory control, i.e. individual variation in inhibitory control performance, heritability of this trait and fitness benefits. Hence, our main objective herein is to conduct a review of the existing literature to discuss conceptual and methodological challenges faced by researchers wanting to study inhibitory control in animals. We then suggest tools to tackle these challenges and propose a framework to build a valid and reliable measure of inhibitory processes. Next, we describe the requirements to study the selective pressures involved in this cognitive process in order to have a better understanding of its evolutionary underpinnings. We finally consider the future of interspecies comparative studies of inhibitory control.