In general, amplitude and latency of the component are considered to be influenced by (unconscious) expectancy,4 task relevance, novelty, contextual constraints,
and motivational significance (see e.g., Nieuwenhuis et al., 2005). Of most interest to our study, the P300 has been assumed to be related to domain-general context-updating processes and to reflect selleck compound the revision of a mental model or the “conditions of the environment” (Donchin and Coles (1988, p. 367); but see Verleger (1988) and the following commentaries). Our design strictly followed a simple pattern of lead-in–context-question–target-sentence, revealing all referents given in the lead-in. The reduced late positivity in response to the sentence-initial object following the topic context could index a reduced need for general context updating, find more because the listener is less “surprised” about the object if previously announced as the topic of the scene compared to the neutral context. Thus, in line with Cowles (2003) who also reported a contextually modulated late
positivity (i.e., the Late Positive Component (LPC)) during sentence comprehension, the late positivity in our study could reflect context-updating processes in terms of the P300. Notably, a number of authors argue against the context-updating interpretation of the P300 in favor of a general reflection of simple attentional, evaluative, or memory mechanisms (for a review, see Nieuwenhuis et al., 2005). Hence, it remains Cell press a matter of debate if late positivities/P600 responses elicited by sentences really belong to the P300 family or whether they should be considered an independent component (e.g., Coulson et al., 1998 and Roehm et al., 2007; see Brouwer, Fitz,
& Hoeks, 2012 for a related discussion of the P600 in response to semantic violations or illusions). The N400 has been described as another ERP component sensitive to discourse level information. It is thought to reflect processing costs for linking an entity to the current mental model (Burkhardt, 2006, Burkhardt and Roehm, 2007 and Wang and Schumacher, 2013). The SDM assumes that discourse linking processes are driven by expectancy as indexed by a modulation of the N400 (see Sections 1.2 and 1.3). In these studies, the degree of inferability, expectancy, or accessibility of an entity in the mental model modulated the N400: The N400 for previously given, expected, or repeated noun phrases was reduced because those entities were easier to link to the current discourse. Importantly, due to the preceding lead-in context in our study which was identical for the neutral and the topic condition, both characters of the scene were discourse-given (Prince, 1981).