Critical Period Of Language Development: Definition, Importance, And Evidence

Nativist and behaviorists views on language development

1. Describe what is meant by the term ‘critical period’ with reference to language development and evaluate the idea that there is critical period for language development.

2. Sam is a Type A, insecurely attached avoidant child. Describe the behaviours you would expect to observe from Sam in the estrange situation task. How would these differ from children showing other attachment styles? What are the effects of being an insecurely attached avoidant child likely to be for Sam?

Language is the main perspective that differentiates human beings from animals.  Language is the reason for many civilizations’ survival.  When writing was not invented, oral recitation of prose and poems for 5000 years is the only reason for the survival of many ancient texts and literatures all around the world. Language is what makes man to stand above all living beings; the emotions are expressed through the use of language by man. Theorists though have developed various approaches to understand the developmental phases of language development. A close connection exists between the development of though and the development of language. Social context and social development also plays role in the development of language. In the development of language various theorists attributes importance to various factors.

Children are pre-programmed and have an innate ability to acquire language was stressed by the nativist views. The importance of the language environment is focused by the behaviourists. The other theorists view was influenced by both cognitive and social development that stressed that the development of language is a complex interaction between the infants and environment.

There are various phases in language development. There are various approaches to understand the language development like Evolutionary, cognitive and social. The critical learning phase starts in early childhood. The initial learning phase of language by man is called critical period of language development. Lennberg (1976) is the first researcher who hypothesized the critical period for language acquisition in his book ‘Biological Foundation of Language’. He emphasized that during the critical period it is easy to gain the normal level of acquisition. According to him this period lasts up to puberty. After that it becomes difficult to acquire the appropriate level of language skills. he also claimed that until this critical period lateralization function of brain increases on its peak and after this period it stops growing.

CPH is based on two main objectives, which are neural functional growth and behavioural growth. If one talks about changes in brain that lasts up to puberty (during the critical period) neuronal cells in brains increases rapidly that helps to develop the language. Parts of the brain that helps to develop language acquisition are in the left hemisphere of the brain; it reaches its maturation after lateralization. Lenneberg explained that at the time of birth both the hemispheres are equal but gradually the parts to control language development are selected down in the left hemisphere after puberty or till up to critical period. Lateralization is division of functions in the brain’s hemispheres. After lateralization the brain loses its flexibility.  The process of lateralization is completed almost around puberty. Both the hemispheres of the brain have equally distributed functions but a few functions like language development skills are performed by both the hemisphere. The left hemisphere is the seat for the grammar and vocabulary while the right hemisphere controls the emotions.

Critical period and its duration

The idea of CPH is supported by three other cases in the past. The cases are about the children and the adults who spent their life in isolation and had no chance to learn language. The two cases are about Isabelle and Genie.

Isabelle was a deaf mute girl and her mother was also deaf. Till the age of six and a half Isabelle led a life of isolation up to the time she was found and rescued. Further with proper care and help she was able to learn language as she was under the critical stage of the language development. Brown stressed Isabelle was able to learn language in two years, that a six year old would learn at her age and at the age of eight she seemed like any other normal child for her age. (Brown, 1958)

The other case is of Genie, a teenage girl who was locked for years by her own father, and later sent to a foster care at the age of 13 and half. Experts found out that Genie’s vocabulary learning capacity was of a five year old way behind for her age group. She had difficulty in learning grammar but was able to use two words like “Mummy play” and negations like “no want milk” her vocabulary learning capacity was way better than grammar learning. The experts also asserted that the difficulty in developing language by Genie was because she did not get proper help in her critical period and she reached puberty; making it difficult for her to get a command on language. (Curtiss, 1977)

A child goes through various stages of language development, which include:

1. Pre-linguistic stage
2. The Holophrase or One-word sentence- 10-13months
3. The Two-word sentence- 18months
4. Multiple-word sentences- 2-2.5
5. Complex Grammatical structures- 2.5-3yrs
6. Adult-Like Language structures- 5-6yrs

In the above mentioned cases the children never got the chance to achieve these milestones. Passing through the developmental phases is essential for the development of effective and efficient language skills.

Another similar case of a lady named Chelsea, she had started t learn her language in her thirties. This case is quite similar to that of Genie because Chelsea could learn to make sentences using syntax only, for example ‘on floor sitting’ or ‘blue the sky’.

According to Lanneberg children who suffered brain damage recovered faster than those children who have completed their critical period of lateralization. These hypothesises of Lenneberg were challenged by Krashen (1982) after considerably re-examining the data Krashen revealed that all the cases where the subjects were under the critical period phase where similar to the adults who were above the critical period age. (Lenneberg, 1967) (Krashen, 1982)

For the further study and understanding of CPH studying the cases of the Down syndrome is critical. Many theorists claim that the children suffering from the syndrome showed sign of slower development compared to the other children from the similar age group. According to Gleitman, these children’s ability to grow is limited as they have passed the critical period of language learning.

As stated by Johnson and Newport there exists a decline in the proficiency of learning with the increase in the age. They also emphasized that though the adults were quick learners in second languages they were not proficient. People who began learning a second language in the childhood achieved higher level of proficiency in accent and grammar. This clearly justifies the idea of the existence of a critical period of learning. Johnson and Newport conducted some research with Chinese and Korean learners, where English was learned as a second language. Most of the adults showed very slow progress. They had difficulty to speak English as they spoke their respective native languages. The ability to pick up the language was quick among these adults but they showed lower level of performance if compared to children. (Johnson & Newport, 1989)

Language milestones and its connection to language development

Similar experiments were conducted by Patricia Kuhl and her colleagues. In their studies, the learning of second language by the subjects highlighted that the sounds are gradually grouped by the brain according to their similarity with the phonemes in the native language. For example: A continuous spectrum of artificial phonemes between /r/ and /l/ when asked to categorize. Not Japanese speakers but native English speakers, tended to perceive sounds as all sounds like either /r/ or /l/. These phenomena Khul has likened to ‘Perceptual magnet.’ Defined by their audio graphic spectrum, related but varying sounds are evidently grouped together. Further eventually is perceived to represent the same phoneme. The process fails to occur without ongoing experience during the critical period. Interestingly these phonetic distinctions compared to normal speech among adults is emphasized by the ‘parentese’ and the ‘baby-talk’ used by parents while speaking to young children actually. (Purves, Augustine, & Fitzpatrick, 2001)

Though Lenneberg’s theory of lateralization and Downs’s syndrome was proved wrong, CPH has always been a central idea of research in language acquisition. Thus language learning for its development entails amplification and reshaping of innate biases by appropriate postnatal experience during the critical period.

2. A child may be emotionally or socially destroyed if he does not get a close and secure relationship with his mother in early childhood. For the development of a child into a responsible adult it is very crucial that the child is given proper care and affection in is early childhood. A sense of support and trust is very essential for a health development in early childhood for a child’s physical as well as mental health.  But as it is said that too much of anything is bad; too much of attachment also hampers the growth of a child.

Various theories and research have been proposed to study attachment but the theory of attachment for the first time was given by John Bowlby in his book “Lasting Psychological Connectedness between Human beings”. According to John attachment is the relationship or a bond developed between the mother or a care giver and the child. Bowlby and other theorists like Mary Ainsworth defined that children are born with innate sense of attachment. Children who get complete support and attachment or care they feel comfort and protection, and these are the children who achieve adulthood safely. The main points of Bowlby theory are:

1. Monotropy: A child has a need to attach one main attachment figure; mostly it is the mother.

2. Bowlby believes that from this one important attachment figure the child should receive continuous care for approximately first two years of his/her life.

3. Reduced intelligence, delinquency, depression, increased aggression and affectionless psychopathy might be the long term consequences of maternal deprivation.

4. Short term separation according to Robertson and Bowlby from teh attachment figure leads to distress.

The three stages of distress given are:

1. Despair,
2. Protest
3. Detachment
4. The development of an internal working model is lead by the child’s attachment relationship with their primary caregiver.

The following figure explains the relationship better:

Source: (Mcleod, 2007)

The relationship between the infant and the mother during the first five years of life is believed by John Bowlby are most crucial to socialization. Higher incidences of juvenile delinquency, antisocial behaviour and emotional difficulties would be resulted if the primary attachment relationship is disrupted.

Cases of language learning in isolation

Mary Ainsworth who has elaborated on the works of Bowlby conducted an experiment to better understand the concept by observing the mother child relationship, observing and assessing the behaviour of child; she named her research the “Strange Situation”. Her experiments which lasted for 20 minutes each she made sequence of events of leaving of mother and entrance of strangers in the experiment room and noted the behaviour and reactions of the child. Mary later categorised her findings into four different outcomes of behaviour. Furthermore her experiments explained three attachment styles-

1. Secure style (B)
2. Insecure avoidant (A)
3. Insecure ambivalent/resistant type (C)

(Ainsworth, Blehar, & Waters, 1978)

As stressed by Larose and Bernier the insecure avoidant type C child like Sam think of themselves as unworthy and unacceptable, due a rejecting primary caregiver. An insecure child finds it difficult to focus on their emotions according to the environment. The children like Sam are very independent of the attachment figure both physically and emotionally. (Larose & Bernier, 2001)

To develop a better understanding let’s take a look at the four types of behaviour classifications.

In a normal situation, from their first years the children learn emotions, they express joy, sadness and anxiety when faced with different stimuli. From the 8 month a child starts to show fear for strangers. He seeks security from the mother when approached by a stranger. Between 7 to 12 months the fear of separation from his mother starts and peaks between 15 to 18 months and after these years it starts to decline.

Secure attachment: According to Ainsworth’s study 70% of children showed insecure attachment behaviour. These children got stressed as the mother left; these children avoided and feared the strangers when the mother was not in the experiment room. On the other hand when the mother was in the experiment room and the strangers approached the children these children played with them. The moment the children reunited with their mothers they showed a sense of comfort and happiness. From the experiment it can be concluded that the children experience joy and are carefree in the presence of their mothers.

Insecure Ambivalent: The ambivalent attachment styled children comprised of 15% in the experiment. These children were severely disturbed. When the mothers left the room these children protested a lot and when the mother returned the children kicked and pushed her away and cried. The children got aggressive and did not show any attachment for a while. These children explored less when they were with their mothers. These children in any condition did not felt comfortable with the strangers; they seemed upset at all times no matter the situation.

Disorganised attachment: These types of children show a lack of clear attachment. The behaviours demonstrated by these children are of avoidance and resistance-mix. They are confused in the presence of the care giver because the care giver acts as the figure of both fear and reassurance. (Main & Hesse, 1990)

Insecure avoidant: These children are very independent of the care giving figure. They are calm when the mother leaves and showed very little distress with the presence of stranger. When they reunite with the mother they do not show much excitement or happiness. In these experiments the children in this group did not explore much of the surroundings. This is due to the care givers insensitivity and rejection of the children needs.

Sam belongs to the Insecure Avoidant type of attachment style. If he were to be in the experiment room he would have show very little reaction to the introduced stimuli. He would have sit calmly with his mother and when the mother leaves and stranger comes in Sam would show no sign of distress. Sam will feel comfort while play with the stranger; he will easily adjust to the presence of stranger in the room and show not much interest when he reunites with his mother. Sam would seem comfortable with both the mother and the stranger. He would interact with the strangers very normally. He will seem to less explore around the room or socialize when with his mother. (Lamb, Gardner, Thompson, & Charnov, 1985)

The children like Sam often belong to a family where alcoholism and drug addiction have resulted in a dysfunctional family. In European countries these same situations were evident in the orphanage. Infants were left in their cribs for long hours and only fed and cleaned and no emotional attachment was extended to them. Thus making them believe as a burden and the babies started to believe that they had very little or no impact on the world. The world to children like Sam is a cold and scary place. (Main & Solomon, Discovery of an insecure-disorganised/disoriented attachment pattern:Procedures, findings, and implications for the classification of behaviour, 1986)

If Sam continues to live like this and the same insensitivity and rejection are used to bring him up he will become a dysfunctional and doomed for an isolated life. He will fail to express his emotions to others. Sam might become developmentally delayed. He may develop to be a passive adult; he may develop an attachment disorder for life. He will grow up to show an awkward behaviour in the social life. The child also develops such insensitivity if he has been abused physically, or witnesses a domestic violence or sexual abuse.  As it is that he brain is hard wired to love the care givers and fear the ones who hurt us the situation when the care giver hurts the child the child’s brain gets dual responses. In the infants brain a dual response is set. A chaos is created in his environment. He would at times ignore people and at times people will ignore him. If this continues for long it will result into anxiety, stress and depression and might make Sam suicidal. Insecure attachment style not only ruins childhood but also adult life.

According to Beck’s cognitive theory of depression it has been evident that the influence of negative cognitions results in the development of depression. The child thus grows into an adult who avoids social life and is isolated life. They show malfunction and maladjustments to the normal social life. A life partner’s intimacy is also not comfortable to these people and then they avoid any physical or emotional attachment to anyone.

These children grow up to avoid relationships and emotions and are very little attached to anyone. If married or in relationship these people show very little distress if the relationship ends. These people avoid intimacy. They give excuses to avoid getting close to their partners. They always fail to support their family or partners when they are needed. People with lack of human contact would eventually die.

If a child develops in a secure environment or in any of the avoidant attachment environment it is necessary for them. Though, it is important that children get proper care and understanding from their mothers. Thus children like Sam grow up to become a dysfunctional part of the society contributing very little. It affects the relationship they form with others whether the relationships are functional or dysfunctional all depends on the early childhood care and development. Thus if seen through the above mentioned theories Sam would grow into develop anti social behaviour, will face emotional difficulties, will not be able to develop functional relationships and also show juvenile delinquencies while growing up.

References

Ainsworth, M. D., Blehar, M. C., & Waters, E. (1978). Patterns of Attachment: A Psychological Study of the Strange Situation. Lawrence Erlbaum Associates.

Brown, E. R. (1958). Words and Things. The Free Press.

Curtiss, S. (1977). A Psychological study of a Modern Day Wild Child. New York: New York: Academic Press.

Johnson, J. S., & Newport, E. (1989). Critical period effects in second language learning: The influence of the matuational statebon the acqusition of English as a second language. Cognitive Psychology , 21, 60-99.

Krashen, S. (1982). Principles and practice in second language acquisition. Michigan: Pergamon.

Lamb, M. E., Gardner, W., Thompson, R. A., & Charnov, E. L. (1985). Infant-Mother attachment: The origins and significance of individual difference in Strange Situation Behaviour.

Larose, S., & Bernier, A. (2001). Social Support Processes: Mediators of attachmetn state of mind. Determinants of infant Behaviour , 3, 96-120.

Lenneberg, E. H. (1967). Biological Foundation of language. New York: NY:John Wiley.

Main, M., & Hesse, E. (1990). Parents unresolved traumatic experiences are realted to infant disorganised attachmetn status:Is frightened/frightening parental behaiour the linking mechanism? University of the Chicago Press.

Main, M., & Solomon, J. (1986). Discovery of an insecure-disorganised/disoriented attachment pattern:Procedures, findings, and implications for the classification of behaviour. Ablex.

Mcleod, S. (2007). Bowlby's Attachment Theory . Retrieved June 3, 2015, from Simple Psychology: https://www.simplypsychology.org/bowlby.html

Purves, D., Augustine, G., & Fitzpatrick, D. (2001). Neuroscience. Sunderland: Sinauer Associates.