ABSTRACT
This chapter evaluates a theory of learnability based on differences in the interpretability status of formal features. It presents the basic assumptions on which the hypothesis of the differences in the learnability status of interpretable and uninterpretable features is built. The chapter also presents information about the subjects who participated in this study, namely, child and adult L2 learners of Greek and Greek SLI children. It presents new data from six Greek SLI children of two different age groups, concentrates on their use of possessive genitive and accusative clitics, as well as of the definite and the indefinite article. Turning to SLI grammars, the notion of (in)accessibility of uninterpretable features refers to problems in the appropriate analysis of the input, due to the incomplete or deficient representation of the functional lexicon. The correlation in the use of third-person clitics and the definite article is also supported by the younger group of child L2 learners and by adult L2 learners.
