In the light of researches and theories, proposed by many linguists and neurologists, “critical period” has a crucial importance as it determines the time period ranging from early childhood till puberty when the second language acquisition or native language appears to be a problematic factor due to “age” and “developmental stages of brain”.

Critical period hypothesis, introduced by neurologists Wielden Penfield and Lamar Roberts in 1959, and popularised by linguist Eric H. Lenneberg in 1967, states that language develops in the first few stages of life and after which, language acquisition is much more difficult and becomes almost impossible.

To strengthen the reflective questions, biological theorists – Penfield and Roberts – argued about “the cellular plasticity of a child’s brain and cellular plasticity which is controlled by the biological clock. With age, the plasticity reduces, thus reducing the capacity to acquire a language”. In extension to this view, Penfield talked about the left part of the brain and allocated the left hemisphere for generating language. Any damage to this part may result in language loss, disorder in speech production, and dysfunction, which includes agrammatism, mostly observed in children and rarely in healthy adults.

Linguist and neurologist Lenneberg proposed his theory of “cerebral dominance” based on the allocation of language to the right and left hemisphere where the left part plays a major role in language acquisition during childhood. And this acquisition generally takes place during early childhood, before puberty, termed ‘critical period’.

Lenneberg further subdivided the learning stages of children accounting them as native learners, early learners, and late learners. His observations, taken in wide notice by Jacqualine and Fussa, gave way to two hypotheses with a clarified stance for all learners, termed the maturational hypothesis and the exercise hypothesis. Stating the maturational hypothesis at this point is eye-opening; it is, the incidence of “language learning blocks” rapidly increases after puberty. Also, automatic acquisition from mere exposure to a given language seems to disappear after this age and foreign language needs to be taught with laboured effort.”

Digging into the prerequisites of brain anatomy and its capacity to endure meaningful input, young children are seemingly blessed with blueprints of language or innate biological endowment/ the capacity to construct simple language sentences, categorised as Universal Grammar, as a result of language exposure. For Chomsky, these small meaningful utterances “has structure and anything with structure and design has intrinsic limits”. In another online article, Universal Grammar is claimed to be an: “… an important aspect of Chomsky’s theory is the argument that human beings are innately predisposed to learn natural languages. Thus, any normal human child can learn any natural language he or she is exposed to… Child’s acquisition takes place in the absence of any negative data (i.e. ungrammatical examples)”.

The author in this abstract emphasised cognitive domains that inhibit the functions of receptors involved in the meaningful learning other than “the basic design of language”. Additionally, L2 learners are thought to be “superior to adults” i.e., the younger the learner, the quicker the learning process. Thus, by relying particularly on the “age” of a child, ‘critical period’ hypothesis aligns the concept of an “optimal period of language acquisition, where learning and relearning of L1 and L2 skills happen to break away from rote learning of language. For Lenneberg, the cerebral asymmetry tends to acquire a definite shape in terms of language learning by age 12.

Another debatable issue i.e., whether ‘critical period’ hinges vocabulary learning or adults tends to enhance their ability? took a bird’s eye view. In the myth of the first three years, Bruer relates that “how we process vocabulary does not change with brain maturation, as one would expect it would if it were a form of time-limited, experience – expectant learning”. It seems instead that the neural circuitry we need to process semantic information and learn vocabulary comes on-line early in development and does not change as we mature, and there appears to be no critical period for vocabulary in a second language.

In addition to Chomsky’s point of view of Language Acquisition and Universal Grammar, the biological composition of brain has led forth the process of lateralisation of the brain, “the term used to refer to any cognitive functions which are primarily located to one side (left hemisphere) of the brain or the other (right hemisphere)”. The cognitive faculties of the brain and functions allocated to both hemispheres have been thoroughly explained by many neurologists. For instance:

“Language is not the only faculty located in the left hemisphere. In general, most of our analytical abilities appear to be concentrated there, too, such as the ability to do arithmetic, to solve an algebraic equation or to decide the chronological order in which things happened”.

And the right hemisphere seems to “soft the mass of sensory data pouring into the brain and organises the mass into comprehensible and familiar patterns”, henceforth, this defines the independent workings to expose our language faculty. It has also been noted that brain damage results in disordered speech irrespective of the critical period of a child. This focuses on the parts of the brain involved for speech production, comprehensive data and grammatical sequencing. In a printed source, neurologists termed the brain damage aphasia (absence of speech), and dysphasia which means “disordered speech”.

Based on the theories and tests conducted on affected infants, we can deduce that a normal baby enjoys its stages of cooing, babbling to two-word stage, telegraphic stage and construction of negative and interrogative analytical sentences in order to show its needs. However, the ones who show symptoms of brain damage are treated or diagnosed through FMRI, PET, MRI.

However, pedagogical strategies, as implied by scholars, have contributed to applying diversified pedagogical strategies to catalyse a learning process through a direct method or audio-lingual approach in order to drill in the basic skills of creating a linguistic pattern with a phonological and semantic rule applied in each lesson. However, L1 and L2 acquisition varies, as supported by researchers, Politzer believed that the syntactical structure of foreign language cannot be acquired the way native language is acquired. Kenji Hakuta, an experimental psycholinguist, observed that the understanding of a second language did not match with the first language learning among adults.

(The writer has done her Master in English and Postgraduate Diploma in English Language Teaching (PGD ELT) from University of the Punjab. She has taught English language, literature, grammar, composition and communication courses, as a lecturer, to intermediate and undergraduates of Government College, Wahdat Colony, Lahore and University of Management and Technology, Lahore (UMT). She can be reached at: [email protected])