On the cost of syntactic ambiguity in human language comprehension: an individual differences approach.

We present an event-related brain potential (ERP) study demonstrating that high and low span readers show qualitatively different brain responses in the comprehension of ambiguous and complex linguistic stimuli. During the processing of ambiguous German sentences, low span readers showed a broadly distributed, sustained positivity, whereas high span participants showed a shorter, topographically more focused negativity. Qualitatively similar effects were observable in response to (complex) object-initial sentences. Additionally, a neural effect reflecting reanalysis in sentences disambiguated in a dispreferred way (P600) was observable only for high span readers, while the low span group showed an N400-like response. These neurophysiological findings support the notion that individual working memory capacity as measured by the reading span test influences sentence processing mechanisms and are compatible with the hypothesis that low span readers cannot effectively inhibit dispreferred readings.