Dissociable effects of prediction and integration during language comprehension: evidence from a large-scale study using brain potentials.

Composing sentence meaning is easier for predictable words than for unpredictable words. Are predictable words genuinely predicted, or simply more plausible and therefore easier to integrate with sentence context? We addressed this persistent and fundamental question using data from a recent, large-scale (n = 334) replication study, by investigating the effects of word predictability and sentence plausibility on the N400, the brain's electrophysiological index of semantic processing. A spatio-temporally fine-grained mixed-effect multiple regression analysis revealed overlapping effects of predictability and plausibility on the N400, albeit with distinct spatio-temporal profiles. Our results challenge the view that the predictability-dependent N400 reflects the effects of either prediction or integration, and suggest that semantic facilitation of predictable words arises from a cascade of processes that activate and integrate word meaning with context into a sentence-level meaning. This article is part of the theme issue 'Towards mechanistic models of meaning composition'.

Large-scale replication study reveals a limit on probabilistic prediction in language comprehension.

Do people routinely pre-activate the meaning and even the phonological form of upcoming words? The most acclaimed evidence for phonological prediction comes from a 2005 Nature Neuroscience publication by DeLong, Urbach and Kutas, who observed a graded modulation of electrical brain potentials (N400) to nouns and preceding articles by the probability that people use a word to continue the sentence fragment ('cloze'). In our direct replication study spanning 9 laboratories (N=334), pre-registered replication-analyses and exploratory Bayes factor analyses successfully replicated the noun-results but, crucially, not the article-results. Pre-registered single-trial analyses also yielded a statistically significant effect for the nouns but not the articles. Exploratory Bayesian single-trial analyses showed that the article-effect may be non-zero but is likely far smaller than originally reported and too small to observe without very large sample sizes. Our results do not support the view that readers routinely pre-activate the phonological form of predictable words.

"I know something you don't know": Discourse and social context effects on the N400 in adolescents.

Adolescence is a time of great cognitive and social development. Despite this, relatively few studies to date have investigated how perspective taking affects on-line language comprehension in adolescents. In the current study, we addressed this gap in the literature, making use of a Joint Comprehension Task in which two individuals with differing background knowledge jointly attend to linguistic stimuli. Using event-related potentials, we investigated adolescents' electrophysiological responses to (a) semantically anomalous sentence stimuli in discourse context and (b) semantically plausible sentence stimuli that the participants believe another individual finds semantically implausible. Our results demonstrate that a robust "N400 effect" (i.e., a well-established event-related potential, known to be sensitive to lexical-semantic integration difficulties)  is elicited by semantically anomalous sentences; this N400 effect is subsequently attenuated by discourse context. Lastly, a "social N400 effect" is elicited by sentences that are semantically plausible for the participants if they believe that another individual finds the sentences implausible. The results suggest that adolescents integrate the perspective of others during on-line language comprehension via simulation; that is, adolescents use their own language processing system to interpret language input from the perspective of other jointly attending individuals.