Who can become native-like in a second language? All, some, or none? On the maturational constraints controversy in second language acquisition

This paper discusses research that has been carried out on maturational con straints for SLA, specifically on the conceptualisation formulated in the c ritical period hypothesis (CPH). Our review shows that the positions taken by researchers are very diverse, something we believe has its basis in a la ck of explicit hypothesis formulation and the use of insufficiently sensiti ve research instruments. Researchers disagree whether all, only some, or no learners can reach native-like ultimate attainment in a second language. W e conclude that there is strong support for maturational constraints, altho ugh the CPH itself cannot be maintained in its original formulation. We als o propose a unitary interpretation of existing empirical results based on t he observation that learners who have been identified as indistinguishable from native speakers characteristically exhibit non-native features that ar e unperceivable except in detailed and systematic linguistic analyses.