Genie spent the first 13 years of her life locked away in a small bedroom in her parents' home. In 1970, her parents were charged with child abuse and Genie began rehabilitation with a team of psychologists and linguists. And scientists were using her experiences to answer the following question: if a person is deprived of language throughout their childhood, can they ever learn enough to be able to communicate well? At first, the answer appeared to be yes. Genie quickly began to learn new words for the objects around her and even say phrases with two or three words similar to how toddlers speak. However, from there, her ability to communicate verbally plateaued. This is because she could not learn grammar, which linguist Noam Chomsky believes separates human language from the communication of animals. It appeared that Genie had passed the critical period of learning human language, which is thought to end around puberty. Scientists have hypothesized that, after a restricted developmental period where the nervous system is particularly sensitive to the effects of a certain experience, in this case, language, it is nearly impossible to learn it. And the same effects have also been shown when learning sign language after the critical period. Now you're probably wondering why there is a critical period in the first place. According to Eric Lenneberg, the linguist who popularized the critical period hypothesis, the function of language tends to settle in the left hemisphere of the brain after the critical period. And it's thought that the brain loses some of its plasticity after this lateralization.