A growing body of research has investigated bilingual sentence processing. How to account for differences in native (L1) and non-native (L2) processing is controversial. Some explain L1/L2 differences in terms of different parsing mechanisms, and the hypothesis that L2 learners adopt ‘shallow’ parsing has received considerable attention. Others assume L1/L2 processing is similar, and explain L1/L2 differences in terms of capacity-based limitations being exceeded during L2 processing. More generally, the role that working memory plays in language acquisition and processing has garnered increasing interest. Based on research investigating L2 sentence processing, I claim that a primary source of L1/L2 differences lies in the ability to retrieve information constructed during sentence processing from memory. In contrast to describing L1/L2 differences in terms of shallow parsing or capacity limitations, I argue that L2 speakers are more susceptible to retrieval interference when successful comprehension requires access to information from memory.

As in any field of scientific inquiry, advancements in the field of second language acquisition (SLA) rely in part on the interpretation and generalizability of study findings using quantitative data analysis and inferential statistics. While statistical techniques such as ANOVA and t-tests are widely used in second language research, this review article provides a review of a class of newer statistical models that have not yet been widely adopted in the field, but have garnered interest in other fields of language research. The class of statistical models called mixed-effects models are introduced, and the potential benefits of these models for the second language researcher are discussed. A simple example of mixed-effects data analysis using the statistical software package R (R Development Core Team, 2011) is provided as an introduction to the use of these statistical techniques, and to exemplify how such analyses can be reported in research articles. It is concluded that mixed-effects models provide the second language researcher with a powerful tool for the analysis of a variety of types of second language acquisition data.

Second language acquisition researchers often face particular challenges when attempting to generalize study findings to the wider learner population. For example, language learners constitute a heterogeneous group, and it is not always clear how a study's findings may generalize to other individuals who may differ in terms of language background and proficiency, among many other factors. In this paper, we provide an overview of how mixed‐effects models can be used to help overcome these and other issues in the field of second language acquisition. We provide an overview of the benefits of mixed‐effects models and a practical example of how mixed‐effects analyses can be conducted. Mixed‐effects models provide second language researchers with a powerful statistical tool in the analysis of a variety of different types of data.

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We report the results from two eye-movement monitoring experiments examining the processing of reflexive pronouns by proficient German-speaking learners of second language (L2) English. Our results show that the nonnative speakers initially tried to link English argument reflexives to a discourse-prominent but structurally inaccessible antecedent, thereby violating binding condition A. Our native speaker controls, in contrast, showed evidence of applying condition A immediately during processing. Together, our findings show that L2 learners’ initial focusing on a structurally inaccessible antecedent cannot be due to first language influence and is also independent of whether the inaccessible antecedent c-commands the reflexive. This suggests that unlike native speakers, nonnative speakers of English initially attempt to interpret reflexives through discourse-based coreference assignment rather than syntactic binding.

Similarity-based interference has played an important role in motivating cue-based models of memory retrieval during language comprehension. One example of interference comes from illusions of grammaticality, where ungrammatical sentences are perceived as grammatical (e.g. 'the key to the cabinets were rusty'). While such effects indicate interference influences perception of sentence grammaticality, less is known about how interference influences the semantic interpretation assigned to a sentence. We report two reading experiments that manipulated sentence plausibility, rather than grammaticality, as a diagnostic of interference. In both experiments, although reading times were longer for implausible sentences, this plausibility effect was reliably attenuated when a distractor item partially matched the cues at retrieval. We interpret these results as being compatible with the predictions of cue-based parsing. The illusions of plausibility that we report indicate that similarity-based retrieval interference has a potent influence on the semantic interpretation that is assigned to a sentence during processing.

We report three eye-movement experiments and an antecedent choice task investigating the interpretation of reflexives in different syntactic contexts. This included contexts in which the reflexive and a local antecedent were coarguments of the same verbal predicate (John heard that the soldier had injured himself), and also so-called picture noun phrases, either with a possessor (John heard about the soldier's picture of himself) or without (John heard that the soldier had a picture of himself). While results from the antecedent choice task indicated that comprehenders would choose a non-local antecedent ('John' above) for reflexives in either type of picture noun phrase, the eye-movement experiments suggested that participants preferred to initially interpret the reflexive in each context as referring to the local antecedent ('the soldier'), as indexed by longer reading times when it mismatched in gender with the reflexive. We also observed a difference in the time-course of this effect. While it was observed during first-pass processing at the reflexive for coargument reflexives and those in picture noun phrases with a possessor, it was comparatively delayed for reflexives in possessorless picture noun phrases. These results suggest that locality constraints are more strongly weighted cues to retrieval than gender agreement for both coargument reflexives and those inside picture noun phrases. We interpret the observed time-course differences as indexing the relative ease of accessing the local antecedent in different syntactic contexts.

Using the eye-movement monitoring technique in two reading comprehension experiments, this study investigated the timing of constraints on wh-dependencies (so-called island constraints) in first- and second-language (L1 and L2) sentence processing. The results show that both L1 and L2 speakers of English are sensitive to extraction islands during processing, suggesting that memory storage limitations affect L1 and L2 comprehenders in essentially the same way. Furthermore, these results show that the timing of island effects in L1 compared to L2 sentence comprehension is affected differently by the type of cue (semantic fit versus filled gaps) signaling whether dependency formation is possible at a potential gap site. Even though L1 English speakers showed immediate sensitivity to filled gaps but not to lack of semantic fit, proficient German-speaking learners of English as a L2 showed the opposite sensitivity pattern. This indicates that initial wh-dependency formation in L2 processing is based on semantic feature matching rather than being structurally mediated as in L1 comprehension.