Psycholinguistic techniques in second language acquisition research Theodore Marinis University College London This article presents the benefits of using online methodologies in second language acquisition (SLA) research. It provides a selection of online experiments that have been widely used in first and second language processing studies that are suitable for SLA research and most importantly discusses the hardware and software packages and other equipment required for the setting-up of a psycholinguistics laboratory, the advantages and disadvantages of the software packages available and what financial costs are involved. The aim of the article is to inspire researchers in second language acquisition to embark on research using online methodologies. I Introduction One of the major differences between first language (L1) and second language (L2) acquisition relates to the level of ultimate attainment. Children acquiring their native language manage within a relatively short period of time to acquire fully the language they are exposed to, whereas this is not the case for adults acquiring an L2. Adult L2 learners typically do not manage to achieve the full acquisition of the L2 grammar irrespective of the amount of exposure they have in the L2. Traditionally, L2 research has focused on the acquisition of grammar. Making use of offline techniques, such as grammaticality judgement, elicitation and comprehension tasks, researchers have investigated issues such as whether Universal Grammar (UG) is available to L2 learners, whether the source of divergence between L2 grammars and native grammars is the inability to reset UG parameters, and whether there is transfer from the first language to the second. In contrast, very little is known as to how learners process an L2 online. Language processing here refers to the mental processes involved while reading or listening to words or sentences in real time, which is also known as ‘parsing’. A considerable amount of research has been carried out in the © Arnold 2003 10.1191/0267658303sr217ra Address for correspondence: Theodore Marinis, Centre for Developmental Language Disorders and Cognitive Neuroscience, Department of Human Communication Science, University College London, Chandler House, 2 Wakefield Street, London WC1N 1PF, UK; email: t.marinis@ucl.ac.uk Second Language Research 19,2 (2003); pp. 144–161