What time period did Lenneberg propose as critical for language acquisition?

Lenneberg proposed that the critical period for language acquisition occurs between approximately 18 months and puberty. This theory is based on the idea that there is an optimal window in which children are particularly receptive to acquiring language. During this period, children can intuitively grasp the complexities and nuances of language with relative ease.

After this critical period, the ability to learn a language as fluently and naturally as a native speaker tends to decline, largely due to neurological and cognitive changes that occur as children transition into adolescence. This notion is supported by observations of children who are not exposed to language during this time, as they often struggle to fully develop language skills later in life, highlighting the importance of early exposure and interaction in effective language acquisition.

The other time periods mentioned do not align with Lenneberg's theory, as they either suggest too early or too late a window for optimal language learning, which fails to capture the significant insights provided by research in this area.