ABSTRACT
This chapter summarizes some of the studies in a research program aimed to identify and to develop psychological principles for improving training in foreign languages. These studies shed light on the following five issues: (1) To what extent does a person adopt or adapt first-language strategies in the acquisition and use of a second language? (2) What are the best methods for efficient and durable acquisition of vocabulary items in a foreign language? (3) What role do abstract linguistic categories play in the acquisition of language skill and the day-to-day use of language? (4) What are the functional units of a language and how do they differ for native and nonnative speakers? (5) How do knowledge of the language and utterance complexity interact to determine message comprehensibility for a listener?
