Symmetries and Asymmetries of Age Effects in Naturalistic and Instructed L2 Learning

The effects of age on second language acquisition constitute one of the most frequently researched and debated topics in the field of Second Language Acquisition. Two different orientations may be distinguished in age-related research: one which aims to elucidate the existence and characteristics of maturational constraints on the human capacity for learning second languages, and another which purports to identify age-related differences in foreign language learning, often with the aim of informing educational policy decisions. Because of the dominant role of theoretically-oriented ultimate attainment studies, it may be argued that research findings from naturalistic learning contexts have somehow been hastily generalized to formal learning contexts. This paper presents an analysis of the symmetries and asymmetries that exist between a naturalistic learning setting and a foreign language learning setting with respect to those variables that are crucial in the discussion of age effects in second language acquisition. On the basis of the differences observed, it is argued that the amount and quality of the input have a significant bearing on the effects that age of initial learning has on second language learning. It is also claimed that age-related studies in foreign language learning settings have yielded significant findings that contribute to the development of an integrated explanation of age effects on second language acquisition.