language

LANGUAGE DEVELOPMENT

Learning objectives for this lecture

Be able to:

± Describe the sensitivity of newborns to language sounds

± Name the main stages of speech development and describe key features of children’s language as they progress through these stages

± Describe the ways in which perception and comprehension of language develops more

rapidly than speech during infancy and childhood

As we examine the remarkable story of how children progress from speechless infants to voluble toddlers and talkative school-children, it is important to remember that language is always a two-way process.  A theme that will recur is that at each stage, language reception outstrips language production.  That, is sensitive to language sounds in early infancy and the ability to understand words and sentences precedes that ability to produce words and sentences in speech and wring.

Having said that, a convenient way to tell the story of language development is to structure the content in terms of speech production – the different stages through which children progress on the journey from their first cry upon emerging from the birth canal to being able to rapidly and easily speak and understand complex sentences.

In this lecture we will take a look at the language abilities of infants and children at five different stages of language production:

Crying and cooing

Babbling

Single words

The two-word stage

Later stages of language learning

Let’s begin by considering the ‘crying and cooing’ stage – from birth unl baby is about 7 months old.

You might think that trying to assess the language ability of young infants, in the first few months of life would be a fool’s errand.  Babies can be very good at vocalising – crying when in distress and cooing when content – but this appears to be non-linguistic. The first word is many months away.

Nevertheless, even at this stage the interactions parents and others enjoy with young infants perhaps embodies the dialogic character of language – the two-way exchange between conversational partners. At this stage, of course, no words are being exchanged.  But, conceivably the two-way exchange of looks (as in peek-a-boo)  and touches can be seen as precursors of the give-and take of language, where speech by one person elicits a reply from another.  

The story becomes even more interesting when switch to considering language reception. Babies appear to lack language, in the sense of lacking speech and being unable to understand words or sentences.  However, there is a more nuanced way of approaching this issue – although young infants are relatively hopeless on the ‘output’ side, in the sense of being unable to speak, we can ask questions about their language ability on the ‘input’ side, by studying their sensitivity to speech sounds.

In recent decades, views about the language abilities of very young infants have changed quite radically. An important impetus for this ship in thinking has been the development of new techniques for assessing the ability of babies to discriminate between speech and non-speech sounds, and within the speech domain, their remarkable ability to discriminate between different kinds of speech sounds. 

Studying language and connive ability in early infancy is difficult!  Unlike older children or adults, babies are liable to fall asleep or become upset or become distracted while the researcher is attempting to engage their attention on a task, such as listening to someone speaking.  Moreover, even if the baby is content, alert and engaged, assessing their response is tricky – obviously, asking a baby to respond by speaking or pressing a button will not work.  In early infancy, the repertoire of behaviours that babies can produce is quite limited.  As we will see, this limitation in the range of acorns that babies are able to make appears to have masked a degree of linguistic sophistication and sensitivity that is present in young infants, and, amazingly, even prior to birth.   

The key to uncovering the remarkable linguistic abilities of young babies has come from thinking about the axons that young babies can perform. One axon that babies perform naturally and spontaneously, since it is essential to their survival,  is to suck on a nipple.   

In pioneering work reported in the early 1970s, Peter Eimers, Einar Siqueland and colleagues at Brown University in the US studied the ability of very young infants, aged 1-4 months, to discriminate different speech sounds.  Their study used the sucking behaviour of infant participants as a window to their ability to perceive language. These abilities turned out to be far more sophisticated than any had supposed. 

The technique they used is now known as ‘High Amplitude Sucking’ and is illustrated on this slide.  The child is provided with a dummy nipple, similar the dummies that are open given to babies.  The key difference is that this dummy is connected to a pressure transducer that senses the strength and frequency of sucks made by the baby.  The transducer is connected, in turn to a computer controlled speech synthesiser. When the child sucks on the nipple, the synthesiser generates a speech sound, that sounds like someone saying a single syllable – such as ‘ba’ or ‘pa’.

Children learn very rapidly that if they suck, they get to hear someone speaking.  Moreover, they find this rewarding, and suck more frequently in order to hear the sound.  On the other hand, hearing the same syllable (‘ba’) over and over again appears to become less and less interesting to the infant, and their rate of sucking declines. The key part of the study is to ask what will happen when the speech sound is changed in some way.   

The particular change that was introduced in this study was to swap the syllable ‘ba’ for the syllable ‘pa’.  This switch was of especial interest because the acoustic components of ‘ba’ and ‘pa’ are actually identical  - the only difference is a change in the relive mind of the sound components, corresponding to the initial consonant (‘b’ or ‘p’) and the vowel sound (‘a’).  When the ‘a’ sound occurs relatively early, adults hear the syllable as ‘ba’; if it occurs somewhat later the syllable is heard as ‘pa’.  The me differences involved here are extremely brief – one fifth of a second.  

The question that Eimas and colleagues wished to ask was this:  can infants as young as one month old also hear this difference?  The answer was a clear ‘yes’.  

At the beginning of each test period, infants sucked more vigorously, as they learned that sucking produced the sound of someone saying ‘ba’.  However, the rate of sucking then declined, as hearing the same sound repeated became less rewarding.  The key observation that when the speech sound  was switched from ‘ba’ to ‘pa’, by making a NY (1/50 second) change in the mind of the acoustic components, infants’ rate of sucking increased again – very dramatically.   

This shows that even at one month of age, infants are sensitive to, and can hear very subtle differences in speech sounds.  

The work by Eimas and colleagues showed that language perception in very young infants was far more sophisticated than had been supposed previously. In the next stage of this work, researchers used the ‘high amplitude sucking’ (HAS) technique developed by Eimas and Siqueland and used it to study language perception and memory at an even earlier stage.   

It is known that the auditory system begins to function even before birth, in the third trimester of pregnancy.  Children are able to hear sounds before they are born. I have a vivid memory of attending a concert with my wife, when she was pregnant with our daughter.  The concert included traditional German music, with loud and regular drumbeats, and I remember my wife nudging me and placing my hand on her ‘bump’.  Our daughter appeared to be enjoying the music and was kicking in me with the drumbeats! (Later on, as a teenager, one of her favourite music genres was – of course – drum and bass.)

In a striking study Anthony DeCasper and Melanie Spence used the HAS technique to ask this question: Do newborns retain any memory of speech sounds heard in utero, before they were born?

This is what they did.  During the last six weeks of their pregnancy, they asked pregnant mothers to sit in a quiet room, and read aloud a passage from children’s story. After the babies were born, the HAS technique was used to evaluate whether they preferred to hear the story they heard before being born, or a novel story.  As in the earlier work, the babies sucking behaviour affected what they heard. By varying their rate of sucking, infants could control whether they heard the ‘familiar’ story or a novel story.  

Remarkably, the results showed that infants had a clear preference for the story that they heard before they were born. Moreover, this preference was apparent, regardless of whether they were listening to the story being spoken by their mother or by another woman.  

It is, of course, important to note that this result does not imply that the infants understood anything about the words and sentences being spoken. However, it does imply that infants were sensitive to the rhythm and varying patterns of intonation in the story – its prosodic features - and that they retained a memory of these patterns.  

The clever design and striking results of this study make it one of my all-me favourites.  Findings such as these have been part of an important shift in the way that we think about infant minds.   

The basic building blocks of speech sounds are called phonemes.  All the words in all the spoken languages of the world are built from these basic units. Of course, the languages of the world are highly varied. Each language makes use of a specific set of phonemes, drawn from the wide range of sounds that can be made by the human vocal apparatus.  Hence, each language makes use of some, but not all of the phonemes that are potentially available.  

As an adult, it is very easy to ‘hear’ differences between various phonemes, if the phonemes in question are part of your nave language.  Conversely, it can be very difficult indeed to hear differences between phonemes, if those phonemes are not part of your nave language.   

•        For example, if you speak Arabic, it will be very easy for you to hear (and say) two different phonemes that both sound like ‘K’ to an English speaker.

•        Hindi includes two different phonemes that would both be rendered as  a‘ T’ sound in English.

•        Conversely, some phonemic disncons that are very salient to an English speaker can be difficult for speakers of other languages. For example, the disncon between ‘L’ and ‘R’ is present in English, but not in Japanese; so, speakers of Japanese can find it difficult to perceive and produce these phonemes.

Thinking about this prompts some interesting questions about the ability of infants to discriminate between different phonemes.  We already know that the American infants studied by Eimas and colleagues were able to hear the difference between the English phonemes ‘p and ‘b’. Accouscally, this is a very subtle difference. What about phonemes from other languages, that the infant has never heard?

Further research using HAS and related techniques has shed fascinating light on this question.  There are two components to the answer. Firstly, very young infants demonstrate sensitivity to any phonemic disncon from any language of the world - or perhaps more accurately, young infants have shown the ability to distinguish between all of the phonemes that have been studied to date. In this respect, the language perception of young infants appears to be better than that of adults, in the sense that young infants appear able to distinguish between a  wider range of speech-sound discoms.   

The second part of the answer is that this wide-ranging sensitivity to speech sounds is quite short lived.  Infants younger than six-months old are sensitive to differences between phonemes drawn from any language.  After 6 months infants become less sensitive to sound discoms that are not part of their speech environment.  It appears that during these early months, infants perceptions become ‘tuned; to the speech sounds that they are exposed to, homing in on the set of phonemes that they hear frequently, and which are used in their language community.  

Work carried out in Sweden and the US has shown that this ‘tuning’ process actually begins very early indeed. In this study, the HAS technique was used to measure the preferences of newborns for vowel sounds that are present in Swedish, but not English, and vice-versa. The arrangement used in the study is shown on the slide.  Babies listened to vowel sounds through headphones, and could control whether they heard Swedish vowels or American English vowels, via the HAS set-up.

The main finding was that newborns preferred to hear unfamiliar vowel sounds that were not present in the language sounds that would have been heard before birth, while in utero. The study was carried in Sweden and the USA. Swedish infants changed their sucking behaviour in order to hear unfamiliar vowel sounds from American English, in preference to familiar Swedish vowels; and

American newborns preferred to hear Swedish vowels, rather than familiar American English vowels. Because the infants were tested shortly after birth, it appears that familiarity with Swedish or

American phonemes sounds would have been based on speech sounds heard earlier, while still in the womb.

As you can see, work using HAS and related techniques has shed fascinating new light on our views of language and cognition in infancy.  Young babies are very limited in what they can do – they lack mobility and require our constant care, attention and love.  However, in recent decades we have learned that the ability of newborns and infants to perceive and remember language sounds is truly remarkable. In a sense, the limited range of actions that babies can carry out seems to mask their sophisticated abilities to perceive and remember.

Although, as we have just seen, young babies arrive in the world equipped with a sophisticated ability to perceive subtle acoustic differences, enabling them to distinguish one phoneme from another, it is important not to under-estimate the complexity of the challenge that needs to be overcome, if speech sounds are to be understood.   

As we saw in the previous part of this module, during normal adult speech, phonemes are arriving at the ears at a rate of about 15 per second.  When we read, the boundaries between words are clearly signalled with spaces.  In contrast, spoken language does not include clear markers telling us where one word ends and the next begins – the stream of phonemes is continuous. This presents newborn babies with a formidable challenge. Where do the different elements of spoken language – words, phrases, sentences - begin and end? The process whereby a continuous stream of speech sounds is divided into words, phrases and sentences is known as ‘parsing’.

Adults often acknowledge this challenge, perhaps implicitly, by adopting a different style of speaking when talking to young children.  You will, no doubt be familiar with this style, which is now known as ‘child-directed speech’. (The older term for this was ‘Motherese’, but of course mothers are not the only people who speak to children in this way.)

Child-directed speech has a number of features: a high-pitched tone of voice is adopted, the person speaks slowly, with exaggerated intonation. This style of speaking appears to help young children to parse the speech signal into words, phrases and sentences. Young children are more sensitive to high frequency sounds, and the slower pace and exaggerated intonation is likely to be helpful, by providing the child with acoustic cues that mark word/phrase/sentence boundaries. Studies have shown that young children generally choose to hear child-directed speech, in preference to adult-to adult speech, when given a choice via HAS or a related technique.

In later years, this does not present a problem, unless we are trying to learn a new language. In this case trying to decode the stream of phonemes into a sequence of words can be very difficult indeed.

For example, in one study, 4m old infants learned to control sound from two loudspeakers. They showed a clear preference for child-directed speech, compared to adult-to-adult talk.

The next stage in the development of speech covers the period from about 7m only around one year of age.  During this me, babies begin to ‘babble’.   

From around 7 months, babies begin to make sounds that are beginning to sound like speech.  You will be familiar with the cute gibberish of this period – repeated syllables such as ‘pa pa’ or ‘ma ma’ are often produced.  It is perhaps no coincidence that these syllables will later be used for referring to the child’s mother and father.  

Babbling appears to be important.  Sometimes children are unable to babble, due to medical procedures.  This can delay subsequent development of speech.

Given that it appears to be important, what is the function of babbling?  One idea is that during this stage babies are basically experiment with the various muscles that we use for speaking. When we speak, a surprisingly large number of muscles are used,, with muscles of the tongue, lips jaw and pharynx all being involved.  Managing to co-ordinate all these fine muscle movements in order to speak clearly is no mean feat!

Steven Pinker describes this by suggesting that when they are babbling, young children are ‘frobbing’ with the speech system.  ‘Frobbing’ is a term sometimes used by engineers to describe what happens when operators are trying to work out how to use an unfamiliar piece of equipment.  In the absence of a user manual, the best option is often to just play around with the controls – what happens if I turn this knob / move this lever / press this button? Perhaps when they babble, young babies are playing the same kind of game, by seeing what kinds of sound they can make, by making different movements in the muscles of the vocal tract.  

Interesting, deaf children who are exposed to sign language during babyhood appear to progress through an analogous stage, which can be described as babbling in sign. During this stage the child is not yet making well-formed signs, but makes gestures with some of the features of signs – in the same way that the syllables made by vocally babbling babies include some of the features of words.  

Moreover, when adults use sign language in this context, they often adopt a style of signing that can be seen as analogous to child-directed speech.  That is, the signs are made more slowly, and with exaggerated movements.

The link on this slide accesses an entertaining video segment of two babbling twins.  Although no actual words are spoken, the babbles made by one twin are evidently a source of great hilarity to the other.

A second striking feature of this video segment, is the prominent use of hand gestures by both twins.  During this proto-communication manual gesturing and vocalising seem to go hand-in-hand (sic).  In the absence of hearing difficulties, language generally migrates to the vocal-auditory channel.  However, as we have seen, an alternative channel, involving manual gestures and vision can also support language.

At around 12 months of age, children produce their first words – often pa-pa, or ma-ma, or ba-ba.

It is worth remembering that babies can generally understand a number of familiar single words well before they say their first word.  Language comprehension leads language production.

Psycholinguists often distinguish between content words, and function and words.

Function words are words such as ‘the’, ‘which’, ‘of’, ‘that’.  These short words play a grammatical role, by signalling relationships between the words and clauses of a sentence – the meaning of words such as ‘the’ or ‘which’ depends on the specific context of the sentence in which they are being used..  In contrast, the meaning of content words is more direct – they refer to a specific object, or quality or action.

This discom is relevant in this context because the first word that a child uterus is more or less invariably a content word, such as Mama, Dada, dog, car and so on.  Function words, such as ‘the’, and ‘of’ and so on are absent, and remain absent in children’s speech for some me.  This is despite the fact that words such as ‘the’ and ‘and’ are probably the most frequent words heard by the child. 

Many developmental psychologists have noted the enormity of the learning challenge faced by every young child, as they learn to parse continuous streams of speech sounds into separate words and sentences, and learn about relationships between words and objects, events, actions and feelings. Remarkably, most children manage to achieve this naturally and effortlessly. The complexity of the challenge is perhaps underlined by the difficulties encountered by AI researchers attempting to reproduce human-level language and thought (although as noted earlier systems such as ChatGPT represent a substantial advance in this direction).

Although most children overcome this challenge effortlessly, becoming fluent conversationalist their journey is not error-free. As every parent will have moved, children tend to use language in their own idiosyncratic way – often to the amusement of adults.  The things that children say form the basis of many an anecdote shared at morning tea!   

When children first begin to produce words, two kinds of errors are typically made.  The first kind are known as over-extension errors. After learning to say a particular word, such as ‘Dada’, it is often applied to a category that is much broader than the specific meaning of the word. That is, the child uses the word ‘Dada’ to refer to any man.  I remember my son point to various men in the street or the supermarket, and saying ‘Dada!’.  Many years later my grand-daughter is using some words in a similar way – any female older than about 15 is a ‘Mummy’.  

Less frequently, children may make the converse error – using a category word to refer to a specific example of the category, rather than the category as a whole. An example of this would be to use the word ‘car’ to refer to the family car, but not other cars; or the word ‘doggie’ to refer to the family dog but not other dogs.

Both kinds of errors are relatively short-lived, with children homing in on the correct meaning of the word – whether it refers to a category, or a specific object or person.

One particular category of word presents the young language learner with particular difficulty – pronouns.

The problem here is that the meaning of these words is highly variable:  When I say ‘I’, I mean me; but when you say ‘I’, you mean ‘you’; and when I say ’you’ I mean ‘you’; but when you say ‘you’, you mean ‘me’.

As adults, we take this fluidity in the meaning of pronouns for granted. But, as you can see working out the meaning of these words, and learning how to use them correctly is challenging for young children.

As with the use of parent-directed speech, adults often acknowledge this problem – perhaps implicitly – by avoiding pronouns when speaking to children.  That is, rather than saying ‘After lunch, we are going to the playground’, one might say ‘After lunch, Grandpa and Frankie are going to the playground’.

At around one year of age, children begin to use their first words.

Although the child may only be using single words, he or she may use their one-word utterances to convey different meanings, depending on the context and the way in which the word is spoken.  For example, a child who is fond of bananas and has learned the word ‘na-na’, might use this single word in several different ways:

•        ‘Nana’ as an act of naming ‘That’s a banana’

•        ‘Na-na!!’ as a request “I am hungry and would to eat some banana – now!!”

•        ‘Na-na’ as a question ‘Is that mashed banana? (Or something else, such as porridge?)

This early use of context, and intonation shows that right from the earliest stages of developing speech, children are sensitive to pragmatic aspects of language.  ‘Pragmas’ refers to the way in which the meaning of words, phrases and sentences can vary according to context and the way in which sentences are spoken.

As we have seen, children are sensitive to speech sounds and can perceive subtle discoms between different phonemes long before they begin to babble, or say their first words. Hence the language reception and language production may have different developmental trajectories.  

With this in mind, one can ask questions about the sophistication of children’s language comprehension at the stage where their language production is modest, comprising single words. When children are at the stage of speaking single words, is their language comprehension also at the level of single words?  Or, do they understand that the meaning of a set of words can change when they are arranged in a different way?

A cleverly designed study showed that 17-month-old infants, at the stage of saying single words, were indeed aware that the order in which words are said can make a big difference to meaning.  In the study, the infants sat in their mother’s lap, in front of two video monitors.  Each monitor showed a brief video sequence, in which actors dressed in the costumes of ‘Big bird’ and ‘Cookie monster’ of Sesame Street fame performed a brief sequence of actions, as shown on this slide.  

On one of the video monitors, Big Bird is shown ckling Cookie Monster, while the other shows

Cookie Monster ckling Big Bird.  As the action begins, the mother of the child either says ’Look Big Bird is ckling Cookie Monster’, or she says ‘Look, Cookie Monster is ckling Big Bird’.  The words in each sentence are, of course identical; but the meaning of those words is very different, depending on the order in which they are spoken.

As the mother speaks these sentences, the looking behaviour of the infant is monitored with a camera.  The results showed that infants usually looked at the video that corresponded to the meaning of the sentence that had just been spoken – Big Bird cking Cookie Monster or vice-versa.

This shows that even though these children were speaking in single words, they understood how the meaning of a group of words in a sentence can change, according to the sequential arrangement of those words - although these children’s language production comprised single words, they had learned that word order is important.  That is, even at this early-stage children were beginning to learn about the syntax of spoken language.

At around 24 months children begin to progress from using single words, to two-word utterances.

The speech that children make at this stage is sometimes known as ‘telegraphic speech’.  Similar to ‘old school’ telegrams, and newer school text messaging, complex meanings are conveyed using very few words – often just two.

Speech during this me continues to be dominated by content words.  Function words are usually absent.

Interestingly, when children are producing two-word, ‘telegraphic’ utterances, their speech is already sensitive to syntax regularise in the language of their home environment. For example, a salient regularity of English syntax is that many sentences conform to this sequence: the subject of a verb usually precedes it, and the object usually appears after the verb (e.g. Tony (subject) plays (verb) piano (object).

Young children at the two-word stage are already sensitive to this syntax rule. For example, when playing ball in the garden, a child at this stage is likely to say, ‘Throw ball’, rather than ‘Ball throw’.

Similarly, if Mummy is holding the ball, the child is likely to say, ‘Mummy throw’, rather than ‘Throw Mummy’.

Obviously, at this stage children are unable to articulate a formal grammatical rule concerning the subject-verb-object sequence in English.  However, their behaviour shows that they are sensitive to regularise in the language to which they have been exposed.  The term descriptive grammar’ is often used in this context – to capture the idea that we are describing the regularise that are a natural part of language – rather than a set of rules that one must follow in order to speak or write correctly.

After speaking their first word, many learn new words and increase their speaking vocabulary relatively gradually at first – acquiring about 3-50 words by 18 months.

At around 18 months, many children experience a ‘vocabulary spurt’ – learning new words at a rapid rate.

It appears that some words can be acquired in a single learning episode, where a new content word is linked with an object or action. This is known as fast mapping.

The age at which children begin their vocabulary spurt is highly variable – sometimes this begins well before 18m, sometimes well after.   

Moreover, not every child experiences a vocabulary spurt – some increase their vocabulary at a relatively steady rate.

So far, we have described children’s development of speech and language in terms of stages with convenient labels – babbling, one-word stage, two-word stage.   How should we describe the later stages of language development, as children begin to communicate using longer and more sophisticated sentences to express complex ideas?  Steven Pinker has suggested that an apt description for the explosion of learning that takes place might be ‘All hell breaks loose’. 

By the me children arrive for their first day of school, their vocabulary is typically around 10-15,000 words. 

An average vocabulary for an adult is about 75 – 100,000 words. How do children achieve this remarkable feat of learning, as they progress from their first words to maturity? A number of studies have focused on specific periods, producing estimates of the rate at which children are learning.  Findings from this work are striking.

Toddlers are generally learning around 3 new words every day.  This increases to 5-8 new words per day in the pre-school years.; and increases again to 10-15 new words per day during the early school years.  

As a parent and now a grand-parent I have always found these numbers quite amazing.  At the beginning of the day, you share breakfast with your child, and at the end of their day you tuck them into bed. In the interim they have managed to tuck all these new words under their hat, and into their growing vocabulary.  And – they do this almost every day!   

It is also worth remembering, that this increase in vocabulary is only part of the story.  In addition to learning new words (semantics), children are also learning all the different ways in which these words can be strung together in sentences.  That is, they are also learning about syntax, and rapidly mastering literally thousands of different sentence structures in their nave language.

Although the way in which language usually develops during childhood represents a remarkable feat of learning, the progression is not error-free.  We have already mentioned the over-extension (and under-extension) errors that children often make when trying to work out the relationship between words, objects and categories of objects.  

As we have seen, when children begin to string words together into sentence, their use of word order shows that even from the earliest stages they are sensitive to syntax. As children begin to use more complex sentence constructions, their sensitivity to syntax regularise remains evident.  The syntax (rule-governed) nature of language seems to be embedded in language acquisition from the earliest stages.  

In a sense this point seems to be underlined (rather than under-mined) when one considers the kinds of errors children make as they navigate through this space and soak up the rules of language.  One kind of error that has attracted particular attention is known as ‘over-regularisation’.  

Over-regularising errors are quite salient in English speakers, but similar patterns have been observed in young speakers of other languages.

These errors are seen in the way that children use the past tense of verbs.  A general rule in English, is that when one is referring to action that happened in the past, the suffix –ed is added to the end of the verb:   

 I peel an apple (now, present tense) vs. I peeled an apple (yesterday, past tense)

Although this rule applies to most verbs in English, it does not apply to all of them.  Some verbs are irregular – as below.  Moreover, many of the most frequent verbs that we use have an irregular past sentence for example:

The past tense of go is went (rather than goed)

The past tense of come is came (rather than comed)

The past tense of run is ran (rather than runned) The past tense of eat is ate (rather than eated)

etc., etc

Interesting when children first begin to use the past tense of the common verbs that are in their early vocabulary, they often use the correct form of the verb.  So, of you ask a toddler what they did before lunch, they may reply “We went to the playground”.

As the child’s vocabulary increases, they learn more and more verbs.  Moreover, most of the new verbs that they learn are likely to be ‘regular’, using the suffix ‘-ed’ to indicate that the action happened in the past. Children readily latch on to this rule, and apply it.  However, in the process of doing this they will often over-apply the rule, and use the  ‘–ed’ suffix for the common, but irregular verbs that they have learned already.

Therefore, several months later you may ask the same child, the same of question again, and receive this answer:  “We goed to the playground”.   Similar kinds of errors may be seen when the child uses other common nouns (e.g. runned, comed, eated, etc.).

These sorts of errors have attracted particular interest, because of the insight they may offer concerning the language learning process. According to an early theory of language learning, originating from the behaviourist tradition in psychology, children learn language by imitating the speech behaviour of others (parents, siblings, caregivers).  The speech behaviour of the child is rewarded by the parents, and as a result this behaviour is more likely to be produced in the future.  This kind of theory is appealing in some respects, but it fails to explain the behaviour that is seen when children begin to produce over-regularising errors.  Firstly, it is clear that when a child says ‘goed’ they are not imitating the language behaviour of an adult caregiver.  It is quite likely that the child has never heard anyone else say ‘goed’.   Secondly, at an earlier me, the child might well have been able to use the past tense of ‘go’ (i.e. went) correctly.  According to the behaviourist theory, this behaviour should have been reinforced (rewarded) and therefore should continue to be used rather than abandoned (albeit temporarily).

To explain over-regularising errors, a different theoretical perspective is required.  Rather than learning a particular behaviour it appears that the child is learning a rule.  In the 21^st century this point seems straightforward – perhaps even trivial.  However, in the pre-Chomsky era of the subject, psychology was very much dominated by the behaviourist tradition. Behaviourists stressed that if psychology aspired to join the fold of scientific disciplines, it was essential to focus on observable behaviours that could be verified objectively, rather than vague ideas about internal mental processes, that could not be observed directly.  Chomsky pointed out that if one wants to understand language, simply focusing on external behaviours completely misses the point.  The overregularization errors made by young children seem to illustrate this quite forcefully.

Following this line of thought, some might say that over-regularising errors are not errors at all.  As they acquire language, children are discovering regularise in the speech around them and then using this learning in their own speech.  As far as they are concerned , words such as ‘goed’, ‘comed’, and ‘runned’ are consistent with what they have learned so far.  Indeed, over-regularising are relatively resistant to overt correction –children may continue to use these constructions for quite some me, before eventually opt for the correct, adult forms. It is clear that children at this stage have no difficulty understanding the adult forms of these verbs, but in their own speech they opt for the over-regularised form, as in this excerpt from a paper by Ursula Bellugi (1971):

CHILD: My teacher holded the baby rabbits and we pated them.

MOTHER: Did you say your teacher held the rabbits.

CHILD:  Yes.

MOTHER:  What did you say she did?

CHILD: She holded the baby rabbits and we pated them.

MOTHER:  Did you say she held them gently?

CHILD:  No, she holded them loosely.

SUMMING UP

•        The development of new techniques, such as High Amplitude Sucking (HAS)) has brought new insight into the sophisticated abilities of newborns to perceive and remember speech sounds.

•        Children typically progress through five stages during the development of speech and language

•        At each stage, the ability to perceive and understand develops more rapidly than the ability to produce language

•        The presence of over-regularisation errors indicates that language learning during childhood involves more than simple imitation and reinforcement (reward) of speech behaviours