An Enigma of Our Own Making: How Methodological Heterogeneity Created the N2 Reversal in Bilingual Language Switching

AbstractThe "N2 reversal enigma," the contradictory finding of whether the N2 ERP component is larger for switch or non-switch trials, has guided bilingual language control research for two decades. This paper argues that the enigma is not a deep neurocognitive puzzle but a methodological artifact. I demonstrate that the opposing findings of Jackson et al. (2001) and Christoffels et al. (2007) emerge from fundamentally different paradigms that tap distinct control processes. Despite extensive theoretical debate, comprehensive factorial testing of key variables remains incomplete, and the Christoffels reversal lacks successful independent replication. Drawing on meta-analytic evidence revealing the absence of robust asymmetrical switch costs (Gade et al., 2021) and training studies showing the N2's malleable nature (Kang et al., 2017; Kang et al., 2023), this analysis concludes that the field has built elaborate theories on an unstable empirical foundation. Rather than seeking to solve this enigma, this paper calls for its dissolution through methodological reform, direct hypothesis testing, and adoption of more robust neural measures such as time-frequency oscillations. The persistent failure to find reliable N2 effects represents science working as it should, eventually self-correcting even cherished assumptions.