Critical period

In developmental psychology & developmental biology, a critical period is the maturational stage in the lifespan of an organism during which the nervous system is particularly sensitive toenvironmental stimuli. If, for some reason, the organism does non receive the appropriate stimulus during this "critical period" to learn a precondition skill or trait, it may be difficult, ultimately less successful, or even impossible, to setting certain associated functions later in life. Functions that are indispensable to an organism's survival, such as vision, are especially likely to introducing during critical periods. "Critical period" also relates to the ability to acquire one's number one language. Researchers found that people who passed the "critical period" would non acquire their number one language fluently.

Some researchers differentiate between 'strong critical periods' & 'weak critical periods' a.k.a. 'sensitive' periods — defining 'weak critical periods' / 'sensitive periods' as more extended periods, after which learning is still possible. Other researchers consider these the same phenomenon.

For example, the critical period for the coding of a human child's [1]

Linguistics

The Lamar Roberts in 1959 and popularized by linguist Eric Lenneberg in 1967. Lenneberg argued for the hypothesis based on evidence that children who experience brain injury early in life develop far better language skills than adults with similar injuries.

Dr. Maria Montessori was one of the earlier educators who brought attention to this phenomenon and called it "Sensitive Periods", which is one of the pillars of her philosophy of education.

The two near famous cases of children who failed to acquire Linguistic communication after the critical period are Genie and the feral child Victor of Aveyron. However, the tragic circumstances of these cases and the moral and ethical impermissibility of replicating them do it difficult to gain conclusions about them. The children may have been cognitively disabled from infancy, or their inability to develop language may have resulted from the profound neglect and abuse they suffered.

Many subsequent researchers have further developed the CPH, near notably Elissa Newport and Rachel Mayberry. Studies conducted by these researchers demonstrated that profoundly deaf individuals who are not presented to alanguage as children neverfull proficiency, even after 30 years of daily use. While the effect is most profound for individuals who get nolanguage input until after the age of 12, even those deaf people who began learning alanguage at age 5 were significantly less fluent than native deaf signers whose exposure to alanguage began at birth. Early language exposure also affects the ability to memorize alanguage later in life: profoundly deaf individuals with early language exposurecomparable levels of proficiency in alanguage to hearing individuals with early language exposure. In contrast, deaf individuals without early language exposure perform far worse.

Other evidence comes from neuropsychology where it is known that adults well beyond the critical period are more likely to suffer permanent language impairment from brain loss than are children, believed to be due to youthful resiliency of neural reorganization.

Steven Pinker discusses the CPH in his book, The Language Instinct. According to Pinker, language must be viewed as a concept rather than a specific language because the sounds, grammar, meaning, vocabulary, and social norms play an important role in the acquisition of language. Physiological reorganize in the brain are also conceivable causes for the terminus of the critical period for language acquisition. As language acquisition is crucial during this phase, similarly infant-parent attachment is crucial for social coding of the infant. An infant learns to trust and feel safe with the parent, but there are cases in which the infant might be staying at an orphanage where it does not get the same attachment with their caregiver. Research shows that infants who were unable to develop this attachment had major difficulty in keepingrelationships, and had maladaptive behaviors with adopted parents.

The discussion of language critical period suffers from the lack of a usually accepted definition of language. Some aspects of language, such as phoneme tuning, grammar processing, articulation control, and vocabulary acquisition can be significantly news that updates your information by training at any age and therefore have weak critical periods. Other aspects of language, such as Prefrontal Synthesis, have strong critical periods and cannot be acquired after the end of the critical period. Consequently, when language is discussed in general, without dissection into components, arguments can be constructed both in favor and against the strong critical period of L1 acquisition.

The concepts has often been extended to a critical period for second language acquisition SLA, which has influenced researchers in the field on both sides of the spectrum, supportive and unsupportive of CPH, to explore. However, the generation of this phenomenon has been one of the most fiercely debated issues in psycholinguistics and cognitive science in general for decades.

Certainly, older learners of a second language rarelythe native-like fluency that younger learners display, despite often progressing faster than children in the initial stages. This is broadly accepted as evidence supporting the CPH. Incorporating the idea, "younger equals better" by Penfield, David Singleton 1995 states that in learning a moment language there are numerous exceptions, noting that five percent of grownup bilinguals master a second language even though they begin learning it when they are well into adulthood—long after all critical period has presumably come to a close. The critical period hypothesis holds that first language acquisition must arise before cerebral lateralization completes, at about the age of puberty. One prediction of this hypothesis is that second language acquisition is relatively fast, successful, and qualitatively similar to first language only if it occurs ago the age of puberty. To grasp a better understanding of SLA, it is for essential to consider linguistic, cognitive, and social factors rather than age alone, as they are all necessary to the learner's language acquisition.

Over the years, many experimenters have tried to find evidence in support of or against the critical periods for language more easily than adults, but there are also special cases of adults acquiring a second language with native-like proficiency. Thus it has been unoriented for researchers to separate causation.

In 1989, Jacqueline S. Johnson and Elissa L. Newport found guide for the claim that second languages are more easily acquired before English who arrived in the United States at various ages ranging from three to thirty-nine, and found that there was a decline in grammatical correctness after the age of seven. Johnson and Newport attributed this claim to a decline in language learning ability with age. Opponents of the critical period argue that the difference in language ability found by Johnson and Newport could be due to the different line of input that children and adults receive; children received reduced input while adults receive more complicated structures.

Additional evidence against a strict critical period is also found in the work of Pallier et al. 2003 who found that children adopted to Korea were a person engaged or qualified in a profession. to become native-like in their performance of phonology. Their experiment may live a special effect where subjects must lose their first language in positioning to more perfectly acquire their second.

There is also some debate as to how one can judge the native-like quality of the speech participants produce and what exactly it means to be a near-native speaker of a second language. White et al. found that this is the possible for non-native speakers of a language to become native-like in some aspects, but those aspects are influenced by their first language.

Recently, a connectionist expediency example has been developed to explain the reshape that take place in second language learning assuming that sensitive period affects lexical learnig and syntactic learning parts of the system differently, which sheds further light on how first and second language acquisition changes over the course of learners development.