In this chapter, we explore key questions about the mental lexicon and brain activity in multilinguals. We begin by discussing research investigating whether languages have separate, integrated, or partially integrated mental representations and how words are processed across languages. We then explore the notion of whether words should be seen as mental representations or brain activity patterns and how lexical processing can be studied in the brain. In doing so, we review advancements in understanding brain function and cognition through multilingual lexicon research using various innovative methods. We address how perspectives on the multilingual mental lexicon can be conceptualized and their implications for theoretical models. Finally, we review research that has contributed to our understanding of bilingual brain function, including short- and long-term changes from multilingualism, and address models integrating behavioral and neurological insights.

Information processing is a process of uncertainty resolution. Information-theoretic constructs such as surprisal and entropy reflect the fine-grained probabilistic knowledge which people have accumulated over time. The information-theoretic constructs explain the extent of processing difficulty that people encounter, for example when comprehending language. Processing difficulty and cognitive effort in turn are a direct reflection of predictability.

Satiation refers to an increase, over time, in the willingness of a native-speaker consultant to agree that a given syntactic structure is grammatically well-formed. Studies show that satiation can be induced under laboratory conditions, within a single testing session; that the effect is restricted to a small number of sentence types (chiefly those involving wh-extraction from wh-islands, subjects, and certain complex NPs); that experimentally induced satiation can persist for at least four weeks; and that satiation sometimes ”carries over” to syntactically related sentence types. Tables are provided showing the methods and findings of satiation studies on seven different types of syntactic violation. Larger issues include (i) whether the satiable sentence types form a natural class within generative syntax; (ii) whether satiation is a unitary phenomenon, or merely a family of similar phenomena; and (iii) how, in principle, satiation can serve as a tool for language research.