Discussion forum Revisiting theoretical and causal explanations for the bilingual advantage in executive functioning Vera Kempe a,* , Neil W. Kirk a and Patricia J. Brooks b a Abertay University, Dundee, United Kingdom b College of Staten Island and The Graduate Center, CUNY, United States The hypothesis of a bilingual advantage in executive func- tioning derives from models of bilingual lexical access, postulating that to access lexical representations in one language, the target language task schema must be selec- tively activated and lexical competitors in the non-target language reactively inhibited (Green, 1998). Bilinguals' routine deployment of selective attention and inhibition in the domain of language is assumed to hone these executive processes to such an extent that far transfer (Barnett & Ceci, 2002) of attentional control to non-linguistic domains ulti- mately occurs. Hence, bilinguals are expected to outperform monolinguals on non-linguistic executive functioning tasks. Paap, Johnson, and Sawi (2015) provide several compelling arguments for why the empirical evidence in support of a bilingual advantage in executive functioning is shaky. We agree that their arguments constitute valid grounds for skepticism, but rather than dismissing the hypothesis entirely, we offer further arguments for why findings have been inconsistent and why, even when a bilingual advantage is evident, the commonly provided causal interpretation might be wrong. The first argument is that many monolinguals might not differ fundamentally from bilinguals in terms of their reliance on executive control processes during lexical access. Many monolinguals routinely switch between different varieties of their native language, such as accents, dialects, or sociolects, depending on interlocutor and context. Models of lexical representation and lexical access have largely ignored the existence of different linguistic varieties (but see La Heij, 2005). To examine whether bidialectal speakers exhibit similar conflict-resolution processes during lexical access as bilinguals, we designed a dialect-switching task requiring participants to name pictures using either a standard or a dialect variety (Kirk, Declerck, Scott-Brown, Kempe, & Philipp, 2014). We compared naming latencies of monodialectal speakers of English with limited exposure to Dundonian, a regional Scots dialect, with bidialectals who routinely use Dundonian in addition to the standard variety of English spoken in Scotland. The results fully replicated findings from bilinguals (Meuter & Allport, 1999): Naming latencies were longer when participants switched between dialect and standard, and cognates were named faster than non-cognates (Christoffels, Firk & Schiller, 2007), suggesting that both vari- eties are active during bidialectal lexical access. Furthermore, bidialectal speakers who routinely used both varieties exhibited symmetrical switch costs, just like balanced bi- linguals (Costa & Santesteban, 2004), whereas monodialectal speakers with limited Dundonian exposure exhibited asym- metrical switch costs such that higher costs were associated with switching into the dominant standard variety. This latter result mirrors findings for unbalanced bilinguals where asymmetrical switch costs reflect task-set inertia because more time is required to overcome the stronger inhibition required to block out the dominant language schema on pre- vious trials (Green, 1998). These results, also replicated with German bidialectals (Kirk et al., 2014), point to the possibility that architectures of lexical representation and mechanisms of lexical access might be fundamentally similar in bidialectals and bilinguals. Consequently, no differences would be expected in executive functioning tasks if bilinguals were compared to bidialectal speakers who, without a sensitive measure of dialect use, * Corresponding author. Abertay University, Dundee, DD1 1HG, United Kingdom. E-mail address: v.kempe@abertay.ac.uk (V. Kempe). Available online at www.sciencedirect.com ScienceDirect Journal homepage: www.elsevier.com/locate/cortex cortex xxx (2015) 1 e3 http://dx.doi.org/10.1016/j.cortex.2015.07.021 0010-9452/© 2015 Elsevier Ltd. All rights reserved. Please cite this article in press as: Kempe, V., et al., Revisiting theoretical and causal explanations for the bilingual advantage in ex- ecutive functioning, Cortex (2015), http://dx.doi.org/10.1016/j.cortex.2015.07.021