EXTRAORDINARY CLAIMS Extraordinary Claims, Extraordinary Evidence? A Discussion Richard M. Shiffrin1, Dora Matzke2, Jonathon D. Crystal1, E.-J. Wagenmakers2, Suyog H. Chandramouli3, Joachim Vandekerckhove4, Marco Zorzi5, Richard D. Morey6, & Mary C. Murphy1 1 Indiana University 2 University of Amsterdam 3 University of Helsinki 4 University of California, Irvine 5 University of Padova 6 Cardiff University Corresponding author: E.-J. Wagenmakers Department of Psychological Methods, room G 0.29 University of Amsterdam, Nieuwe Achtergracht 129B The Netherlands Letter: PO Box 15906, 1001 NK Amsterdam Parcel: Valckenierstraat 59, 1018 XE Amsterdam Email:
[email protected] 1 EXTRAORDINARY CLAIMS Abstract Roberts (2020) discussed research claiming honeybees can do arithmetic. Some readers of this research might regard such claims as unlikely. The present authors used this example as a basis for a debate on the criterion that ought to be used for publication of results or conclusions that could be viewed as unlikely by a significant number of readers, editors, or reviewers. Keywords: Evidence, publication criteria, numerical cognition, extraordinary claims, comparative cognition 2 EXTRAORDINARY CLAIMS Rich Shiffrin: When I saw a report by Roberts (2020) summarizing research showing that honeybees can do arithmetic, I was intrigued by the claim: As a non-expert in fields of animal cognition and models of numerosity, my initial reaction was skepticism: Especially when I think of the difficulty of teaching mathematics in secondary education in the US, the claim that honeybees do arithmetic of the sort we attempt to teach students seemed unlikely. As we shall see in the dialogue to follow, there are decent arguments that honeybees could produce the data in the experiments in question.