[The effect of individual-level variables on speech act performance, Section II. Empirical foundations]
Many factors affect the realisation of speech acts, including sociocultural norms, being a native or nonnative speaker, situational parameters of the exchange, and individual differences in personal characteristics. This chapter focuses on findings related to the last set of factors and specifically on personality (extraversion), aptitude (and its related construct, proficiency), and motivation. These multicomponent traits are distinct constructs but are not entirely discreet from each other. In a review of literature that incorporates second language acquisition and interlanguage pragmatics, their dynamic relationship and their effects on speech acts are described, with an eye toward discerning the relative contributions of these variables to the expression (and interpretation) of second-language speech acts and to offering suggestions for future research.