Reconceptualizing the critical period hypothesis for second language acquisition: An appraisal of Lenneberg's work on the epigenesis of language

The critical period hypothesis (CPH) as an explanation of age effects on language learning has been a perennial source of contention in the field of second language acquisition (SLA). Although this hypothesis – which suggests that adult language learning is constrained by biological or maturational changes in the brain – has been based on the work of Eric Lenneberg (i.e. Biological Foundations of Language, 1967), it does not reflect Lenneberg's original biological theory of language. In this paper, the CPH is examined in light of a comprehensive review of Lenneberg's work and related disciplines. By outlining Lenneberg's notion of epigenesis in language development, it is argued that the CPH interpretation of the critical period notion that has long skewed the debate over age effects in SLA must be re-evaluated, and that any reference to “Lenneberg's CPH” can – and should – be abandoned.