As reviewed in the Introduction, the published literature on frontocentral NoGo N2 (N2 effect) suggests a few possibilities of its functional significance. The first considers NoGo N2 as reflecting inhibitory processing (e.g., Falkenstein et al., 1999; Jodo and Kayama, 1992; Kopp et al., 1996; Lavric et al., 2004). A second views N2 as an index of response conflict monitoring rather than inhibition (Botvinick et al., 2001; Botvinick et al., 2004; Donkers and van Boxtel, 2004; Jonkman, 2006; Kopp et al., 2006; Nieuwenhuis et al., 2004; Nieuwenhuis et al., 2003; Ridderinkhof et al., 2004a; Ridderinkhof et al., 2004b). A third view suggests that N2 reflects neither inhibition nor conflict (e.g., Bruin et al., 2001; Smith et al., 2007).
