Lenneberg (1967) suggested that there is a critical period for language development. Evidence to support this claim has come from Johnson and Newport's (1989) study of immigrants and Curtiss' (1977) study of Genie

Describe the findings of either Johnson and Newport (1989), or Curtiss (1977). Discuss how the findings support the critical period hypothesis. Additionally, discuss one limitation of the findings that prevents the study from being definitive.

What will be an ideal response?

Johnson and Newport (1989) examined the grammatical mastery of immigrants who arrived in the USA between ages 3 and 26 . They found a relationship between age of arrival and mastery of the English language, such that the older the immigrants were when they arrived, the lower their degree of mastery. Many people who arrived in the USA before age 7 were indistinguishable from native speakers, whereas many people who arrived after the age of 15 performed very poorly. This supports the critical period hypothesis because it suggests that language learning is easier the younger you are. Further, it suggests that mastery is unlikely to be achieved if you start learning language after the age of 15 . One limitation of the study is that it is correlational. There may be other factors related to age of arrival (e.g., amount of time spent speaking your native language after learning English) that are responsible for the finding. Curtiss (1977) studied a child named Genie who was found as a teenager after being confined to a small room for most of her life. Genie did not start learning language until she was almost 14 . Although she was able to learn some aspects of the language, she was not able to acquire many of the more subtle aspects of grammar, such as passive constructions. This supports the critical period hypothesis because it provides an example of someone who was not able to master language because she did not start learning language until her teenage years. One limitation of the study is that it is a very unusual case. It is hard to make firm conclusions based on Genie's performance because she may have had additional cognitive and/or social difficulties in addition to her language-learning difficulties.