Critical Period Hypothesis

Lenneberg formed the Critical Period Hypothesis theory which contends that language is innate but has to be attained before the age of puberty or else the ability to learn language ebbs (as a result of the lateralization of the brain). 1 At present, the Critical Period Hypothesis theory is widely accepted by numerous linguists. Evidence has been presented that there is a limited time when the brain is malleable (in terms of language). Studies such as, linguistically isolated children (a.k.a. feral children) support Lenneberg’s theory of the critical period because they are unable to fully acquire language. 2 Moreover, there is a non-uniform success rate in adults who try to attain a second language yet children can obtain a new language a lot more quickly and sufficiently than adults. 3 It is thought by many that a critical period for acquisition of a language does exist.

The most common contrasting viewpoint against the Critical Period Hypothesis is the theory presented by Noam Chomsky. Chomsky hypothesized that people are born with a set of rules known as ‘Universal Grammar’; thus people can acquire language at any point within their lifetime as long as they are placed in an adequate learning environment.4 Although many linguists concur with Chomsky’s views about Universal Grammar; the movie, “Nell” can be interpreted in such a way that Chomsky’s theory is erroneous. In the movie, the character Nell learned a language within her critical period made up of the distorted English from her mother (who had a speech defect as the result of a series of strokes) and words remembered from a private language spoken with her twin.

However, when she was being taught English in her late 20’s, Nell showed little progress in using the English language and continued to speak in her own language.6 In the film, the audience never witnesses Nell communicate in correct English sentences; most probably because she doesn’t learned English syntax. Hence, there is a critical period in which the brain is malleable and if language is not learned within that time span, language acquisition becomes difficult and sometimes unattainable.

There have been several studies that strongly support Lenneberg’s hypothesis. Among the most prominent are feral children. Feral children are persons that have been linguistically isolated. When they were found, most were unable to pick up on language abilities.7 These cases propose that there may be a ‘critical age’ in which any child who has somehow missed out on learning a language will never fully master one. The most famous of these cases is Genie. Genie was a 13 year-old girl who was denied human interaction.8 When she was discovered, she only knew two words.9 Although upon discovery, a team of scientists tried to teach her language.10 They wanted to prove the falsehood of Lenneberg’s hypothesis. However, this did not happen. Genie never learned proper grammar or sentence structure. Other cases of feral children include: Victor, the wild boy of Aveyron (who was found at age 11) and Kamala of Midnapore (who was found at age 8), both never learned language correctly either.11 Therefore, although Lenneberg’s hypothesis is not proven, feral children forcefully support it.

The Critical Period Hypothesis is further supported by experiments about second language acquisition. Lenneberg believed that “the language acquisition device, like other biological functions, works successfully only when it is stimulated at the right time” (p. 19).12 Studies conducted by Patkowsky in 1980 suggest that a critical period does exist.13 Patkowsky did research on immigrants to find out if younger learners received higher syntactic proficiency than the older ones.14 The results illustrated that immigrants exposed to English at pre-puberty learned English well, but the ones exposed to English at post-puberty received a range of scores.15 Nonetheless, Patkowsky noted that children were far more able to acquire language than adults, most likely because their brains hadn’t been assigned specific functions.16 Thus, this experiment is further evidence that supports Lenneberg’s theory of a critical period existence.

In conclusion, numerous linguists believe that there is a ‘Critical Period’ in which humans can acquire language. The theory proposed by Lenneberg about a limited time in which language can be acquired is supported by large amounts of research (which include feral children and second language acquisition). Although many challenge this hypothesis with the theory of ‘Universal Grammar’, both are unproven. Nonetheless, I believe that the Critical Period Hypothesis holds more merit than the theory of Universal Grammar because through everyday life, I have witnessed people who have passed their critical period fail to acquire second language to the degree of its native speakers. Hence, the Critical Period Hypothesis theory is a strong hypothesis that is most likely to be proven in the future.