The Critical Period Hypothesis for L2 Acquisition: Does the Evidence Support its Existence?

In this essay, I explore the Critical Period Hypothesis (CPH) in language acquisition, which suggests the existence of a specific time frame during which humans can achieve native-like fluency in a second language (L2). I begin with a historical overview highlighting the methodological issues and criticism of statistical analysis in CPH studies. I mention two contemporary studies, Hartshorne et al. (2018) and Chen & Hartshorne (2021), which I posit to be good examples of how to respond to statistical critiques. I discuss critiques of CPH research methodology, focusing on issues such as the lack of a clear definition for the critical period (CP), variations in experimental designs, and the effects of the native language on second language acquisition. I propose a hypothesis linking the CP to the development of logical thinking in children and suggest using neuroimaging techniques, i.e., ERP and fMRI, to investigate this connection, drawing on proposals by Krashen (1975) and Rosansky (1975) to connect CPH with the theories of Inhelder & Piaget (1958). In summary, the CPH for language acquisition remains a topic of debate, but recent studies have provided stronger statistical support. I encourage continued research to better understand the CP and its relationship with cognitive development.