Applied Psycholinguistics 27 (2006), 3–42 Printed in the United States of America DOI: 10.1017.S0142716406060024 KEYNOTE ARTICLE Grammatical processing in language

The ability to process the linguistic input in real time is crucial for successfully acquiring a language, and yet little is known about how language learners comprehend or produce language in real time. Against this background, we have conducted a detailed study of grammatical processing in language learners using experimental psycholinguistic techniques and comparing different populations (mature native speakers, child first language [L1] and adult second language [L2] learners) as well as different domains of language (morphology and syntax). This article presents an overview of the results from this project and of other previous studies, with the aim of explaining how grammatical processing in language learners differs from that of mature native speakers. For child L1 processing, we will argue for a continuity hypothesis claiming that the child’s parsing mechanism is basically the same as that of mature speakers and does not change over time. Instead, empirical differences between child and mature speaker’s processing can be explained by other factors such as the child’s limited working memory capacity and by less efficient lexical retrieval. In nonnative (adult L2) language processing, some striking differences to native speakers were observed in the domain of sentence processing. Adult learners are guided by lexical–semantic cues during parsing in the same way as native speakers, bu