Chapter 8

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Differences between child and adult learning


Have you ever wondered why children seem to be “better” at learning languages than adults? Are you currently learning a new language? What are some of the difficulties you experience in the process of learning this new language? How is this different from the way you learned a language as a child? In this blog, we will discuss some of the most significant differences between child and adult learning of a second language, and also a few of the most significant contributing factors to these differences.

Second Language Acquisition (SLA) is a process which people learn another language other than their first language, or the field of study that investigates this process. SLA differs from bilingualism or multilingualism in the sense that it is not learnt simultaneously but at a later stage after the first language has already been acquired. First language (L1) refers to the language inputs from either family or caretakers from the womb to around 5 years of age. This also means that there can be more than one input language. Second language (L2) refers to the additional language learnt after the L1 (first language) period. Here, we will treat language acquisition and learning interchangeably.

A second language can be learnt in a naturalistic or formal environment. When a language is learnt through formal instructions, it is referred to as a foreign language. However, for better understanding, we will not make a distinction between foreign language and second language.

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Critical Period Hypothesis

One of the crucial underlying concepts that account for the differences in second language acquisition (SLA) between children and adults is the critical period hypothesis. The boundaries between what is defined as a ‘child’ in SLA and what is defined as an ‘adult’ in this blog is mainly based on this theory.

Eric Lenneberg (1976) hypothesised that language acquisition in human beings was affected by biological growth (i.e. as a person ages). In his claims, the age of adolescence (after puberty, about 13 years old) is a transitional point at which the brain reaches a biologically mature state. Because of this, there is a firm localisation of language processing in the left hemisphere of the brain (i.e. language processing has already been ‘fixed’ in a particular part of the brain) after puberty. This then, causes difficulties in language acquisition after puberty.

Although the critical period hypothesis was originally applied to L1 acquisition, studies have shown that the effects are also extended to L2 acquisition. For example, a research conducted by Jacqueline S. Johnson, and Elissa L Newport (1989) compared L2 English proficiency of 46 native Korean or Mandarin speakers who had arrived in the US between the ages of 3 and 26. The subjects were tested on structures of English grammar, using a grammaticality judgement task. The test results showed that participants who arrived in the US before the age of puberty (i.e. before 13 years old) performed better at the test, as compared to participants who had arrived in the US after the age of puberty. It is also important to note that the performance among participants who arrived in the US after 13 years old was variable (at lower scores). The results generally supported the authors’ prediction that the critical period for the acquisition of language is also extended to second language acquisition.

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Learning Methods

One of the ways in which adults and children differ in second language acquisition is in the learning methods. Such methods include simultaneous learning, sequential learning, and learning in naturalistic settings and in formal classroom settings. These differences in methods will be discussed in detail below.

Learning Methods – Children

Second language learning can be listed in two ways: simultaneous and sequential learning (Halgunseth, 2010). Simultaneous learning involves younger children who are exposed to more than one language since birth. However, this type of learning is categorised under bilingualism. Second language learning is more of a sequential learning in either a naturalistic or formal setting. This involves children who are already familiar with one language then introduced to another at the later part of their childhood. A naturalistic setting may include language learning in the neighborhood when the child might meet and mix with children who speak other languages; or more commonly, in a more formal setting like school. Take for example, in the Singapore context, a child who speaks Mandarin Chinese at home but is required to learn English in school. This change might trigger some stages of learning in child SLA. At the initial stage, when a child is newly exposed to a new language, it is normal for him to persist using the first language even though the others do not understand. When the child realizes that he is not understood, he will enter a stage where he chooses to communicate nonverbally instead of verbally. At the next stage, the child will start speaking in small utterances using the new language. At the final stage, when the child has already acquired enough of the second language, he will be able to construct sentences to express themselves. Although the sentences might be very basic or contains grammatical mistakes in the beginning, it will gradually improve overtime.

HS moved with his Korean family to Singapore at the age of 4. He entered a local kindergarten at the Nursery level. When he first came to school, he communicated with the teachers in Korean. However, after he realizes that he is not understood and the teachers kept asking him to speak in English, he decided to not speak at all and start pointing to things to communicate. After a period of time, he was able to start saying single words like: toilet, please, teacher, no, yes etc. Slowly, he started to speak in longer sentences like: Teacher, I want toilet. This is an example of a child who went through all four stages of SLA through sequential learning.

Learning Methods – Adults

Second language learning in adults may happen in a naturalistic or formal classroom setting. A naturalistic way would be within a target language speech community although this is usually rare. More commonly seen is learning in a formal classroom setting. Adults usually receive explicit instructions and less input while children tend to receive more “enjoyable” language activities (Nikolov, 2009). Also in classroom contexts, adults are usually required to talk and learn. They do not go through the same learning stages children do and they are less likely to go through the silent period children do (Stewart, 2003). In naturalistic contexts, adults are usually forced to communicate for survival. For example when a refugee flees to another country, he is forced to adapt to their language and is able to because of his need and motivation. The other factors will be discussed in the following sections.

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Significant Contributing Factors

It is also important to note that there are a few factors that contribute to the differences in the way second language is acquired in children and adults. Such factors include physiological characteristics, cognitive abilities, self-consciousness, and motivation. These will be discussed in detail in the next few pages.

Physiological Characteristics

Physiological characteristics refer to the physical functions of a human. According to the critical hypothesis theory, children who have not reached the critical age are still physically and biologically immature and have neurological advantages in learning language as compared to adults (Lenneberg, 1967).Their speech organs and brains are more flexible which also make it easier for them to speak with a more accurate pronunciation and intonation (Lenneberg, Penfield & Roberts, 1960). Adults, on the other hand, are less flexible in their speech organs and more limited in developing native-like proficiency because their tone and pronunciation of a second language are often affected by their first language.

Cognitive abilities

Cognitive abilities are brain-based skills that develop over time and it includes mechanisms of learning, memorizing, problem-solving, and attention-paying human use to carry out tasks. Thus being said, adults are more developed in their cognitive skills and should be more apt in learning a language. However, a study by Finn et al. (2014) suggest that learning with effort hinders aspect of language learning like phonological organization of category structure but facilitates word segmentation. In addition, adult learners are also reported to be faster and more efficient in the early stages of learning and master some domains such as vocabulary better than children. This can be explained by Jean Piaget’s Theory of Cognitive Development (1955), that children depend largely on their sensory experience to learn and understand. But adults are able to use their more superior cognitive ability like abstract thinking to comprehend and infer.

Children rely principally on sensory experience for reflecting and acquiring knowledge,and they understand things directly or through audio visual aids and other sensory inputs. Since adults are more cognitively mature,they are better able to use their ability of abstract thinking to comprehend knowledge indirectly and inferentially.


Even with limited proficiencies, children are known to be more at ease than adults when attempting to use a new language as they do not consciously monitor their progress the way adults do. Adults on the other hand, have the fear of making mistakes and embarrassing themselves. Stephen Krashen’s Theory of Second Language Acquisition (1982), includes a ‘monitor’ hypothesis which is the result of a learned grammar. This system will plan, edit and correct the second language. However, when overused, it will cause a lack of self-confidence which will lead to over self-consciousness then ultimately become a problem in the SLA process.


The Theory of Second Language Acquisition also includes an Affective Filter hypothesis which states that higher motivation, self-confidence, a good self-image, and a low level of anxiety are building blocks of success in SLA. A low level in these factors can create a ‘mental block’ in the learner and prevent learning. Although these factors are positive, they alone are insufficient for SLA to take place (Schütz, 2014). Younger learners’ motivation might be lower, as at many times, they are forced to take up a second language. However the motivation might be higher if they need to rely on the second language for everyday communication, or if they are voluntarily learning the L2 based on interest. The same goes for adults who are learning out of interest. However, adults are often tied down with so many other commitments that sometimes they are unable to fully concentrate on the learning. Adults who have to depend on the L2 for practical needs like communicating with business clients for example, also have a higher motivation and are thus able to learn more effectively than adults who do not have such motivations.

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Regularization is a phenomenon in language acquisition and language development whereby irregular forms in morphology and syntax are often replaced by a regular one. For example geese are often regularized as Gooses.

Learners exposed to inconsistent input appear to change the language as they learn it, making it more regular. Children will almost always regularize inconsistent forms. Adult learners, however, will only regularize the most complex inconsistencies (Kam et al., 2009) An example would be a study done by Singleton and Newport in 1994, the study was based on a child named Simon, who was profoundly deaf and received no other ASL input as he attended a school where no ASL was signed in addition he has no contact with other children who knew ASL. So his only form of ASL contact was his parents who have both learned ASL in their mid to late teens. This made his scenario very rare and unique because while Simon is a native signer of ASL, his parents are non native signers. However even so, his parents provided him with his only linguistic model of ASL. Simon’s and his parents’ production of a particular class of morphemes in ASL (morphemes of movement) was studied. An example of morphemes of movement can be seen in the figure below.

The parents were found to use these morphemes inconsistently, producing them around 70% of the time in obligatory contexts. In contrast, Simon used these forms very consistently, around 90% of the time in obligatory contexts. This level of consistency was equivalent to that seen in the productions of control children who had been exposed to native ASL. So it was hypothesized that Simon reorganized the inputs so that his own linguistic system was rule-governed. We will refer to this process as ‘regularization’. A form of refularization would be overregularization.

One reason adults and children differ in their language acquisition abilities is that they also differ in other cognitive capacities: for instance, the relatively poor memory and/or processing abilities of children may make them more likely to over-regularize inconsistent input.


Overregularization often also known as overgeneralization takes place on both lexical and morphological level. On a lexical level, it would be overregularization on word learning. Overextension would occur while they are learning the language. Which means children would tend to generalize the meaning of the word beyond the word sense in the adult language. An example would be how all 4-legged animals can be referred to as a dog.

On a morphological level, there is both the derivational morphemes and inflectional morphomes. Overregularization is observed in derivational morphemes in forms such as how the prefix ‘un-’ can be added to many verbs to denote the reversal of an action but children often tend to overregularize this rule to yield forms such as ‘unblow’ which means deflate or ‘unlight’ which means to extinguish.

Overregularization is needless to say, commonly seen in inflectional morphemes, the regularization of the past tense marker ‘-ed’ is a very good example. As mentioned, children tend to overregularize this rule to form words such as ‘sitted’ stead of sat or ‘bringed’ instead of brought.

Reasons/hypotheses for Overregularization in Children

  • The presence of Irregular forms

One possible reason is that Children set up rules for their acquisition of a language. This hypothesis is backed up by the Dual mechanism model whereby it suggests that there are 2 mechanisms, rule and memory. So for example the rule is that ‘-ed’ denotes past tense marker. Memory would be the correct forms at work. In cases where recall from memory instantly retrieves the correct form the rule would not be executed. However if the in cases where retrieval does not happen fast enough, the rule would be executed. And in the cases of children because their encounter is still limited. In addition, they have relatively poor memory and/or processing abilities hence when exceptions appear, it would make them more likely to over-regularize inconsistent input as well.

  • Figuring out the grammatical rules

Children produce terms such as ‘bringed’ and ‘goed’. However these forms do not appear in adult speech. Hence it is sure that they have not learned this words from adults therefore it is not through imitation that they acquire these words. A possible explaination for that would be that children are figuring out grammatical rules themselves and would later modify their rules to accomodate the exceptions as well.

  • Yet to fully acquire verb meanings

It is also possible to hypothesize that children have yet to fully acquire the meaning of the verbs due to their limited encounters. Therefore they are unable to assimilate the verbs into its narrower semantic classes. An example would be how children classifies the word ‘told’ and ‘whispered’ as a mode of communication, hence overregularizing the word to form sentences like the one in the example below:

“Susan whispered me a story” instead of “Susan told me a story”.

Reasons for Overregularization in Adults

Adult language learners also tend to overregularize morphological and syntactical patterns, however unlike children’s overregularization, the overregularization in adult learners remain in their system and adult learners do not grow out of it (Kam et al., 2005).

One example of this is from a study on adult learners of German observed by Klein and Perdue (1993),would be how adult learners of german uses the indefinite article ‘eine’ (which denotes plurarity and feminine form) indiscriminately even though German has many indefinite article forms are used in correspondence with the gender of the noun (these genders can also be masculine or neuter).

  • The presence of Low Frequency Verbs

In addition, the dual mechanism model mentioned in the overregularization in children takes place in adults as well. It goes without saying that the more practice a speaker gets with the language the better the retrieval however in cases such as low frequency verbs, due to the less frequent contact, retrieval may fail and hence rule would be executed. For example low frequency verbs such as leapt and dove may be said as ‘leaped’ and ‘dived’ instead, due to the lack of contact with the irregular forms.

  • Complex Input

In addition, adults also tend to overregularize more when the input is more complex. Adults tend to overuse morphemes on nonobligatory context for example, a perfective form is used instead of an imperfective aspect.

“As a boy I went to New york” (perfective: has end point)

“As a boy i used to go to New york” (imperfective: does not really have an end point)

This can be explained by how the second language is interfered by the native language. The learning of the second language is made more difficult with the interference by the native language. Because grammatical rules are set in place while acquiring the native language but both native and second language may not share a similar set of grammatical rules hence it cannot be applied throughout.

Less is more Hypothesis

This hypothesis suggests that the relative cognitive deficits in children helps with the second language acquisition as it enables them to isolate and analyze the separate components of a linguistic stimulus. This means that children have yet to fully acquire the meaning of the verbs which hinders their progress of assimilating the verb into its narrower semantic class. Take the example shared above, told and whispered both denotes a mode of communication however with the cognitive deficit (which in this case is the lack of lexical terms) the child might overgeneralize and say: “She whispered me a story” instead of “She told me a story” because to them both means a mode of communication. This difference is an advantage to children because with their limited memory resource, it would allow them to ignore the variability and focus on smaller linguistic units as a basis for learning the grammar of the language hence, acquiring the second language more efficiently.

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“Ultimate Attainment”

When most authors refer to “ultimate attainment” of an L2, they refer to the ability to attain native-like proficiency in an L2.

In many past studies, it has been shown that children, as compared to adults, are more likely to attain native-like proficiency at a second language, especially in areas such as grammar, and the production and perception of speech (Finn, Lee, Kraus, & Kam, 2014).


Child L2 learners are less likely to produce ungrammatical sentences as compared to adult L2 learners, especially in morphological errors such as the incorrect addition or omission of the plural -s in English (Finn et al., 2014). Adult L2 learners also tend to produce entire phrases or sentences that are inconsistent with the internal phrase or clause structure, as compared to child L2 learners (Finn et al., 2014).

In a study conducted by Becky H. Huang (2013), it was found that the age at which L2 learners acquire the L2 affects grammaticality judgement. In the study, the participants involved comprises 118 Mandarin-English bilingual immigrants in the United States (English is the L2), and 24 English native speakers from the United States. The native speakers were included as they were the control group. The bilinguals spoke only Mandarin before they were 5 years old. This was to ensure that English was indeed the L2. Also, before the bilinguals arrived in the US, they did not have much exposure to English (e.g. being enrolled in English-medium international schools). The bilinguals had also lived in the US for a minimum number of 6 years, with at least 3 consecutive years. This is to ensure that they have attained some level of acquisition of the L2. The last criteria that the bilinguals have met was that they were not diagnosed with hearing issues, language disorders, or learning disabilities.

All the participants took a grammaticality judgement task. In the task, 84 English sentences were taken from past studies on English morphosyntax acquisition. Of which, there were 42 pairs of grammatically correct and incorrect pairs, and the sentences contained parts of speech found in standard English grammar. Sentences were presented to participants one at a time on a laptop. Participants were asked to judge whether or not a sentence was grammatical via keyboard response on the laptop. The results of this study showed that L2 learners in general performed poorer than the native speakers, as predicted. Within the L2 learners, bilinguals who arrived in the US at a younger age (and thus was exposed to English at a younger age) performed better at the grammaticality judgement test, as opposed to the bilinguals who arrived in the US after the age of 13. The former group managed to correctly judge grammatical and ungrammatical sentences on an average of 84% of the time. Some of them have also achieved near-native proficiency in grammar, with a score of about 90% accuracy (native speakers had an average score of 95% accuracy). Participants who arrived in the US after the age of puberty managed to correctly judge the grammaticality of the sentences on an average of 62% of the time. These results then show that children are more able to attain native-like proficiency in L2 grammar, as compared to adults.

Speech production

In the same study, Huang (2013) also studied speech production in L2 learners across different ages. In her study, she found that the age of arrival of the L2 learners had a more significant impact on speech production than on grammaticality judgement. In the speech production test, the L2 bilinguals were asked to read a paragraph aloud twice, and their speech was recorded for listeners to rate the speakers. The listeners were native English speakers from a university in Southern California, they were around 25 years old, grew up in the US, and were linguistics majors or former English teachers. The rating was done on a scale of 1 (strong perceived foreign accent) to 9 (native speaker accent), and this was to indicate the level of foreign-ness in accents of speakers in each recording. The results of the speech production ratings were such that speakers with a younger age of arrival (arrived in the US before 13 years old) scored an average of 7 to 9 on the rating of foreign accent (closer to native speaker accent), whereas speakers who arrived in the US after the age of 13 obtained average scores ranging from 1.5 to 4 (closer to strong perceived foreign accent) on the rating of foreign accent. These results show that younger L2 learners are more likely to attain native-like proficiency in speech production as opposed to older L2 learners.

In another example, a study done by James Emil Flege, Murray J. Munro, and Ian R. A. MacKay (1995) examined native Italian L2 learners of English who were immigrants living in Canada. In their study, they accessed the relation between the age of acquisition and the general degree of foreign accent in L2 learners’ production of sentences in English. In the study, participants were native Italian speakers who had begun learning English in Canada when they were between the ages of 2 to 23 years old. The average number of years that the participants have lived in Canada was 32 years. The native Italian participants were asked to produce various sentences in English. These utterances were recorded, and native English-speaking Canadian listeners were asked to rate the sentences spoken by the Italian participants on a continuous scale. There was also a control group comprising native English-speaking Canadian speakers who were asked to produce the same sentences for listeners to rate. The results of the experiment showed that a majority of the Italian participants who had started learning English after 13 years old received ratings outside of the native English range (i.e. stronger perceived foreign accent), and participants who started learning English from a younger age (between 2 years old to about 13 years old) mostly received ratings that were closer to the native English range.

Why did these researchers study accent rating? To many educators, and native speakers (like native speakers of English, for example), accent is a measure of perceived fluency and proficiency in a language. This means that the closer an L2 learner’s accent is to a native-like accent, the more fluent he/she is perceived to be. Hence, the results of the above studies show that L2 learners who started learning English as children were eventually perceived to be more orally proficient in English than L2 learners who started learning English as adults.

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Improvements for future research

Many of the research articles had limitations in the way ‘child’ and ‘adult’ are defined. Generally, according to the critical period hypothesis, participants under the age of 13 were considered as children, and participants above the age of 13 were considered as adults. However, the results of most of the research displayed stratified data for an in-between age group (13 to 18 years old). This affected the overall discussion of the results because this particular age group performed in ways that overlapped with children’s performance in L2 production and adult’s performance L2 production. This caused the data collected to be varied and stratified among the ‘adult’ age group (above 13 years old). Perhaps future research can propose a separate ‘adolescent’ group for the transitional age group to account for the stratified data.

For example, Karen Melissa Lichtman (2012) proposed an argument against the Critical Period Hypothesis – that the change from implicit language learning to explicit language learning does not only happen abruptly at the age of puberty. The change happens gradually and continuously throughout life. In this sense, the decline in the ability to achieve native-like proficiency in a language slowly declines with age, and not abruptly after the age of puberty, hence providing reason for a transitional ‘adolescent’ age group to be studied.

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In conclusion, we have explored and discussed the differences in L2 acquisition between Adults and children in the areas of learning environments, physiological characteristics, cognitive abilities, self-consciousness, motivation, regularization, overregularization, ability to attain native-like proficiency in L2, grammar, and speech perception. These areas of differences are based on the understanding of the critical period hypothesis. It is also important to note that although current research show that these various aspects of language learning exhibit differences between children and adults, often the boundary of what is defined as “child” and “adult” is unclear, hence future research could be improved in this area.

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First created by Ow Li Xuan Viola, Priscilla Tan Yi Jia, Zheng Shiyang, AY2014/15 Semester 1