Implicit semantic prediction error can account for N400 effects on articles that do not differ in meaning: A neural network model

N400 effects on indefinite articles (a/an) compatible or incompatible with expected nouns have been initially taken as strong evidence for probabilistic pre-activation of phonological word forms, and recently been intensely debated because they have been difficult to replicate. Here, we simulate these effects using a neural network model of sentence comprehension that we previously used to simulate a broad range of empirical N400 effects. The model produces the effects when the cue validity of the articles concerning upcoming noun meaning is high, but fails to produce the effects when the cue validity of the articles is low due to adjectives presented between articles and nouns during training, providing a possible explanation for the small size of the effects in empirical studies. The model accounts for article induced N400 effects without assuming pre-activation of word forms, and instead simulates these effects as the stimulus-induced change in a probabilistic representation of meaning corresponding to an implicit semantic prediction error.