These dimensions are many and various. Affective factors such as learners’ personalities can influence the degree of anxiety they experience and their preparedness to take risks in learning and using an L2. Learners’ preferred ways of learning (their ‘learning styles’) many influence their overall orientation to the learning task and the kind of input (for example, spoken or written) they find it easiest to work with. We will focus on two of the major dimensions here —language aptitude and motivation—and also explore how differences in learning strategies can affect development.
Research involving language aptitude has focused on whether and to what extent language aptitude is related to success in L2 learning. There is strong evidence that it is. Learners who score higher on language aptitude tests typically learn rapidly and achieve higher levels of L2 proficiency than learners who obtain low scores. Furthermore, research has shown that this is so whether the measure of L2 proficiency is some kind of formal language test or a measure of more communicative language use.
Most of the research on the relationship between language aptitude and L2 proficiency took place in the 1950s and 1960s and, therefore, predates the birth of SLA. From an SLA perspective the key question is: How does language aptitude relate to the processes of interlanguage development? One interesting possibility is that different components of language aptitude may be implicated in different stages of processing. Phonemic coding ability would seem relevant to the processing. Phonemic coding ability would seem relevant to the processing of input, grammatical sensitivity and inductive language learning ability to the central processing stages involving interlanguage construction, and memory to the storage and access of language. However, such a proposal, while interesting, remains speculative.