Ambiguous terminology in animal personality research: a self-report questionnaire and a systematic review
Whether animal personality studies provide insights of broader evolutionary and ecological relevance to behavioural ecology is frequently questioned. One source of controversy is the vast, but often vague conceptual terminology used. From a statistical perspective, animal personality is defined as repeatable among-individual variance in behaviour; however, numerous conceptual definitions of animal personality exist. Here, we performed a 1) self-report questionnaire and 2) systematic literature review to quantify how researchers interpret conceptual and statistical definitions commonly used in animal personality research. We also investigated whether results from the questionnaire agree with those of the literature review. Among the 430 self-reported researchers that participated in our questionnaire, we observed discrepancies in key questions such as the conceptual definition of animal personality or the interpretation of repeatability. Our literature review generally confirmed the global patterns revealed by the questionnaire. Overall, we identified common disagreements in animal personality research and discussed potential solutions. We advocate for the usage of statistically-oriented terminology because conceptual definitions can seemingly be interpreted at multiple levels of biological organization. We expect that adopting such statistically-oriented terminology will, at least partly, avoid the confusion generated by the label “animal personality”, and ultimately help to clarify and move the field forward.