The performance of cleaner wrasse, Labroides dimidiatus, in a reversal learning task varies across experimental paradigms.

Simon Gingins,Océane Krattinger,Fausto Quattrini,Redouan Bshary,Sandra A. Binning,Sharon Wismer,Fanny Marcadier

doi:10.7717/peerj.4745

Abstract

Testing performance in controlled laboratory experiments is a powerful tool for understanding the extent and evolution of cognitive abilities in non-human animals. However, cognitive testing is prone to a number of potential biases, which, if unnoticed or unaccounted for, may affect the conclusions drawn. We examined whether slight modifications to the experimental procedure and apparatus used in a spatial task and reversal learning task affected performance outcomes in the bluestreak cleaner wrasse, Labroides dimidiatus (hereafter “cleaners”). Using two-alternative forced-choice tests, fish had to learn to associate a food reward with a side (left or right) in their holding aquarium. Individuals were tested in one of four experimental treatments that differed slightly in procedure and/or physical set-up. Cleaners from all four treatment groups were equally able to solve the initial spatial task. However, groups differed in their ability to solve the reversal learning task: no individuals solved the reversal task when tested in small tanks with a transparent partition separating the two options, whereas over 50% of individuals solved the task when performed in a larger tank, or with an opaque partition. These results clearly show that seemingly insignificant details to the experimental set-up matter when testing performance in a spatial task and might significantly influence the outcome of experiments. These results echo previous calls for researchers to exercise caution when designing methodologies for cognition tasks to avoid misinterpretations.

Highlights

Cognition is broadly defined as the way organisms acquire, store, process and act upon information obtained from their environment (Shettleworth, 2010)
How to cite this article Gingins et al (2018), The performance of cleaner wrasse, Labroides dimidiatus, in a reversal learning task varies across experimental paradigms
Many researchers have adopted a comparative approach when studying the evolution of cognition: by testing a variety of species in the same cognitive tasks, researchers aim to understand how cognitive skills are distributed across taxa, and why (Emery & Clayton, 2004; MacLean et al, 2012; Salwiczek et al, 2012; Burkart et al, 2014; Gingins & Bshary, 2016)

Summary

Introduction

Cognition is broadly defined as the way organisms acquire, store, process and act upon information obtained from their environment (Shettleworth, 2010). To this end, many researchers have adopted a comparative approach when studying the evolution of cognition: by testing a variety of species in the same cognitive tasks, researchers aim to understand how cognitive skills are distributed across taxa, and why (Emery & Clayton, 2004; MacLean et al, 2012; Salwiczek et al, 2012; Burkart et al, 2014; Gingins & Bshary, 2016). Whether in a comparative context or not, failing to notice or account for these biases may lead to inappropriate conclusions with regards to the behavioral or cognitive abilities of a group

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