Large N400 sentence context effects are elicited when a participant’s only task is to read or listen, confirming the intuition that semantic processing is what humans naturally do with language (i.e., the default). Moreover, similar magnitude effects were observed even when some secondary task – semantic, phonological, or graphemic in nature (Connolly et al 1990) – was imposed. When single words instead of sentences served as the prime, task demands had more of an effect. Although typically larger when instructions explicitly called for semantic analyses, reliable N400 effects (but not necessarily concomitant RT priming) were nonetheless observed in situations where semantic processing was not necessary nor even beneficial. Moreover, N400 amplitude modulations were clearly seen with experimental manipulations aimed at minimizing controlled processes (e.g. of stimulus onset asynchrony, proportion of related stimuli, level of processing: reviewed in Holcomb 1988). Importantly, then, N400 measures revealed ongoing semantic processing even when such analysis was orthogonal to task performance and not evidenced in overt behaviors (e.g., Kuper & Heil 2009). Still, in all these types of studies, participants directed their attention to the
