How pragmatic interpretations arise from conditionals: Profiling the Affirmation of the Consequent argument with reaction time and EEG measures q Mathilde Bonnefond a,b,⇑ , Jean-Baptiste Van der Henst a,⇑ , Marion Gougain a , Suzanne Robic a , Matthew D. Olsen a , Oshri Weiss a , Ira Noveck a,c,⇑ a Laboratoire sur le Langage, le Cerveau et la Cognition (L2C2), CNRS Université Lyon 1, France b Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, The Netherlands c Centre de recherche français à Jérusalem (CRFJ), CNRS-MAEE, Israel article info Article history: Received 29 November 2011 revision received 20 July 2012 Available online xxxx Keywords: Conditional reasoning Experimental pragmatics N200 P300 P600 abstract Conditional reasoning consists in combining a conditional premise with a categorical pre- mise and inferring a conclusion from them. Two well-known conditional arguments are Modus Ponens (MP: If P then Q; P//therefore Q), which is logically valid and Affirmation of the Consequent (AC: If P then Q; Q//therefore P), which is not. The latter is often accepted as true on pragmatic grounds under the generally accepted assumption that the conditional premise is transformed so as to justify a biconditional reading (p if-and-only-if q). We present results from two experiments – one using self-paced measures and the other electroenceph- alography (EEG) – while comparing participants’ evaluations of MP and AC arguments. Based on prior work, we anticipated finding two types of individuals as a function of their endorsing or rejecting AC arguments. The self-paced task (Experiment 1) shows that Rejecters of AC arguments are linked to especially long response times with respect to Endorsers and, criti- cally, shows that AC argument’s minor premise prompts slowdowns among all participants compared to MP’s. The EEG study (Experiment 2) reveals that the minor premise in AC argu- ments prompts both Rejecters and Endorsers to produce an N200 wave, which the literature associates with a violation of expectations. These findings suggest that the second premise of AC arguments arrives unexpectedly even among those who are ultimately Endorsers. We describe how these findings impact the conditional reasoning literature. Ó 2012 Elsevier Inc. All rights reserved. Introduction The conditional is arguably the most studied logical expression in the cognitive sciences. Entire books are de- voted to If (Evans & Over, 2004) and explanations concern- ing its comprehension hold a central place in linguistics (e.g. Horn, 2000), philosophy (e.g., Stalnaker, 1968), and, of course, in the psychology of reasoning (Braine & O’Brien, 1991; Johnson-Laird & Byrne, 1991). One of the reasons it garners so much attention is that it is often linked with inference forms that are pragmatically justifiable while not being logically valid. 0749-596X/$ - see front matter Ó 2012 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.jml.2012.07.007 q The authors wish to thank Victor Ferreira and three anonymous reviewers for their incisive comments. This work was supported by a Fyssen foundation grant awarded to the first author and by the French ANR ‘‘Neuroreasoning’’ awarded to the last author. ⇑ Corresponding authors. Addresses: Donders Institute for Brain, Cog- nition and Behavior, Radboud University, Kapittelweg 29, 6525 EN Nijmegen, The Netherlands. Fax: +31 (0)24 36 10989 (M. Bonnefond), L2C2, CNRS Université Lyon 1, Institut des Sciences Cognitives, 67, Bd Pinel, 69675 Bron, France. Fax: +33 (0)4 37 91 12 10 (J.-B. Van der Henst and I. Noveck). E-mail addresses: m.bonnefond@fcdonders.ru.nl (M. Bonnefond), vanderhenst@isc.cnrs.fr (J.-B. Van der Henst), noveck@isc.cnrs.fr (I. Noveck). Journal of Memory and Language xxx (2012) xxx–xxx Contents lists available at SciVerse ScienceDirect Journal of Memory and Language journal homepage: www.elsevier.com/locate/jml Please cite this article in press as: Bonnefond, M., et al. How pragmatic interpretations arise from conditionals: Profiling the Affirmation of the Consequent argument with reaction time and EEG measures. Journal of Memory and Language (2012), http://dx.doi.org/10.1016/ j.jml.2012.07.007