Do animals have a personality and if so why and how can we measure it? These questions were addressed by a group of psychologists and biologists. The psychologists warned biologists not to make all the mistakes the psychologists had made 50 years ago and challenged the biologists to clarify their concept, the definitions they are using and the methodology used. Biologists admitted that among the many papers recently published quite a few show weaknesses in the methodological approach and the description of the phenomenon. Often, the concept of ‘personality’, ‘temperament’, ‘behavioural syndrome’ and coping style are used as if they were describing identical phenomena. Nevertheless, there was no doubt that the phenomenon of individual difference in behavioural phenotype exists in animals and may even be pervasively present, including in invertebrates. However, we identified as the more interesting and less investigated question how individuals develop a personality. How important are environmental influences (including those of social partners) and how genetics are involved in the establishment of a behavioural phenotype. In addition, we discussed whether we can expect a ‘personality’ to be stable over ontogeny and the entire life history of an individual. Shouldn't we rather expect personality to change during development since the individual needs specific adaptations to every stage of its life cycle? And wouldn't an updating of information gathered during fetal or early development during adolescence be useful and functionally required for animals living in poorly predictable environments? On the other hand, it might not be economical or even possible for an individual to limitlessly change its behavioural (and underlying physiological) phenotype, and particularly when this has its bases in early development. Here the question of interactions between maternal effects and individual experiences was addressed by several speakers. These questions were hotly debated as was the role of genetics in determining personality. Should the research strategy be to search for genes with major effects or for QTL-loci (loci with quantitative effects on the phenotype)? How much would that tell us about the construction of personality in comparison to a more thorough study of self-organization during development? Discussion on the last day of the workshop pinpointed the need for more thorough study of the ontogeny of personality and stressed the necessity of further development of models in this field that would allow more hypothesis driven studies rather than the collection of further descriptions of phenomena. Discussants also stressed the need for repeated measurement of the same individuals over longer time spans and across a wider variety of contexts than has been previously the case in this admittedly still young field. Participants agreed to write a series of papers on the proceedings of the workshop that will be published in the journal Developmental Psychobiology.
Liv Baker (Vancouver), Alison M. Bell (Urbana, IL), Hans-Joachim Bischof (Bielefeld), Katrin Blawat (München), Mark Briffa (Plymouth), John P. Capitanio (Davis, CA), Romain Clément (Berlin), Nils Cordes (Champaign, IL), Sasha R.X. Dall (Exeter), Melanie Dammhahn (Göttingen), Jana Eccard (Potsdam), Björn Forkman (Frederiksberg), Eva Fucikova (Bielefeld), Samuel Gosling (Austin, TX), Giulia Gracceva (Groningen), Ton Groothuis (Groningen), Anja Günther (Bielefeld), Antje Herde (Bielefeld), Sylvia Kaiser (Münster), Thomas Klefoth (Berlin), Jaap M. Koolhaas (Groningen), Lars Lewejohann (Münster), Stephanie Lürzel (Münster), Caroline Müller (Bielefeld), Marc Naguib (Heteren), Klaus Reinhold (Bielefeld), Heiko G. Rödel (Bayreuth), Tim Ruploh (Bielefeld), Gerhard Sagerer (Bielefeld), Norbert Sachser (Münster), Ina Schicker (Füssen), Katja Siegeler (Münster), Andrew Sih (Davis, CA), Volker Stefanski (Stuttgart), Martin Tremmel (Bielefeld), Jana Uher (Berlin), Kees van Oers (Heteren), Nikolaus von Engelhardt (Bielefeld), Joe Waas (Wageningen), Franz J. Weissing (Groningen), Benjamin Zipser (Münster)