Do Control Questions Influence Behavior in Experiments? * Catherine Roux † and Christian Th¨ oni ‡ March 2013 Abstract Outcomes and strategies shown in control questions prior to experimental play may provide subjects with anchors or induce experimenter demand effects. In a Cournot oligopoly experiment we explore whether control questions influence subjects’ choices in initial periods and over the course of a repeated game. We vary the framing of the control question to explore the cause of potential influences. We find no evidence for an influence of the control question on choices, neither in the first period nor later in the game. JEL Classification: B41, C72, C91 Keywords: Control questions; Experimenter demand effects; Anchoring; Experimental design * Financial support from the Richard B¨ uchner-Stiftung is gratefully acknowledged. The usual disclaimer applies. † University of St.Gallen. E-mail: catherine.roux@unisg.ch ‡ University of Lausanne. E-mail: christian.thoeni@unil.ch; Web: http://sites.google.com/site/christianthoeni 1