Brain & cognitive development

Annotations:

• The physical structure of the brain is related to childrens cognitive and language development. Different areas of the brain performs different functions

1. Postnatal brain development (after birth)

   Annotations:

   • Postnatal development for brain and cognitive development, influenced by both genes & environment
   • The slower timescale for postnatal development is so that later stages of brain development can be influenced by interaction with the outside environment. The opposite brain was quicker, and born with more mature brains, then much more of their brain development would take place in the relatively limited environment of the mother’s womb
   • Delayed development is associated with a relatively larger volume of cerebral cortex, and an especially large prefrontal cortex. The Prefrontal Cortex Its ability of higher Mental functions Eg. Planning & initiations of actions & the inhibitions of irrelevant behaviour(executive functions)  
   1. Huttenlocher (1990) & Synapses

      Annotations:

      • has reported a steady increase in the number of synapses in several regions of the human cerebral cortex. For example, in parts of the visual cortex Synapses growth begins around the time of birth and increases to a peak level well above that observed in adults
      • A characteristic feature of the later stages of brain development, then, is a decrease in the overall number of connections among nerve cells from about the first year of life onwards. This pruning of connections is important because it may be one mechanism by which specialization of function in different regions of the cortex is achieved
   2. Plasticity
2. Prenatal brain dev.

   Annotations:

   • The basic blocks of the brain are called neurons.  Neurons nerve cells that receive information and pass it on to other nerve cells in the form of electrochemical impulses.
   •  After conception the human embryo develops a structure called the neural tube that will eventually transform into the different parts of the human brain Neurons are born through the process of cell division. Second, they migrate from the place of their birth to their final locations in the brain. Third, once they take on their final shape and form this process is called differentiation.
   • One feature of the differentiation is the growth and branching of dendrites.  The dendrites of a neuron are like antennae that pick up signals from many other neurons and, if the  　 circumstances are right, pass the signal down the neuron’s axon and on to other neurons. The pattern of branching of dendrites is important, because it affects the amount and type of signals the neuron receives. The points of communication between neurons are called synapses (see Figure 3). Synapses begin to form in the brain in the early weeks of gestation. The generation of synapses occurs at different times in different areas of the cortex.   
   • A second aspect of differentiation that occurs in most neurons is myelination. Myelin (see Figure 3) is a fatty sheath that forms around neurons and helps them to transmit signals more quickly. It begins to form around neurons before birth and continues to do so for many years, even into adulthood in some areas of the cortex. When myelination is delayed, a delay in development can also occur,
   • At the same time that the brain is growing and increasing in size and complexity, regressive events are also occurring. For example, It is estimated that 20–50 per cent of neurons die during development because of errors in cell division, because they were only temporarily needed, or because they are simply surplus to requirements. In adults, the brain has a very specific pattern of branching of dendrites and synapses between cells
   • The are 100 billion neurons and cells that make up the human brain because of this there is  selective ‘pruning’, through which useful connections remain and surplus ones are eliminated.
3. Is the brain innately pre-specified

   Annotations:

   • Genes pre-specified, inborn, inherit
4. Is the brain structured epigenesis

   Annotations:

   • Or whether the brain develops in response to the environment of the child. An epigenetic view suggests that brain development occurs as a result of the child developing in an external environment which affects the course of brain development Epigenesis - Development by means of interaction between genes and environment
   • Do they unfold from a predefined genetic blueprint, or are they dependent upon the child’s interactions with the environment? We conclude that these cognitive functions develop according to epigenetic principles, with genes and environment inextricably linked
   1. Genetic determinism/determined

      Annotations:

      • Genetic determinism/determined is the view that there is a pre-specified ‘genetic blueprint’ which imposes itself on the developing child in a direct way, and which is minimally affected by environmental factors. Specifically, genetic determinism holds that brain development is the unfolding of a genetic plan, and that maturation in particular regions of the brain causes or allows specific advances in cognitive, perceptual or motor abilities in the child. This represents a classically nativist perspective on development.

Annotations:

• Specialises in performing different cognitive functions. One way of thinking about this ‘functional specialization’ within the human brain is in terms of cognitive modules

1. Breakdown of Cognitive modules

   Annotations:

   • Cognitive modules help to map what we know about brain function (what the brain does) to brain structure (its physical make-up).
   • Cognitive development : 　 Do they unfold from a predefined genetic blueprint, or are they dependent upon the child’s interactions with the environment? We conclude that these cognitive functions develop according to epigenetic principles, with genes and environment inextricably linked
   • Genetic determinism/determined is the view that there is a pre-specified ‘genetic blueprint’ which imposes itself on the developing child in a direct way, and which is minimally affected by environmental factors. Specifically, genetic determinism holds that brain development is the unfolding of a genetic plan, and that maturation in particular regions of the brain causes or allows specific advances in cognitive, perceptual or motor abilities in the child. This represents a classically nativist perspective on development.
2. How modules develop
   1. Neural modules

      Annotations:

      • Neural modules are real, structural units of the brain. There is plenty of evidence for their existence
   2. Cognitive modules

      Annotations:

      • Cognitive modules, on the other hand, are hypothetical constructs that provide a way of thinking about how the different functions of the brain might be performed
      1. Modulization - Karmiloff-Smith

         Annotations:

         • View is that modularization occurs as the brain develops The environment influences the structure and function of modules over the course of evolution in a ‘phylogenetic’ sense (to do with the long-term development of a species over many generations). In other words human brains have become modular through adaptations to the environment, during the course of evolution.
         • Karmiloff-Smith proposes that modules are the product of development; that the human mind modular as a result of development
         1. KS Self orgainisation of the brain

            Annotations:

            • For example, in the case of brain development, the cerebral cortex alone contains some 100,000,000,000,000 (also written as 1014) synapses. It is unlikely that the genes can (in any direct way) encode the full information necessary to generate this level of complexity according to a predetermined plan (Elman et al., 1996). This is another argument in favour of an epigenetic view of brain development, and in favour of Karmiloff-Smith’s argument that modularization happens as a product of development
      2. Modulization Fodor (1983) - Innately

         Annotations:

         • is the key advocate of innately specified modularity. Arguing from a nativist standpoint, he asserts that humans are born with the innate capacity to develop information processing systems that allow them to make sense of the world in which they have evolved.
         • In contrast he does not believe that the environment plays a crucial role in their development in an ‘ontogenetic’ sense (that is when it comes down to understanding the development of a given individual child).
3. Summary

   Annotations:

   • Cognitive modules are hypothetical constructs that may help psychologists to understand the relationship between the brain’s structure and its functions.  
   • Fodor argued from a nativist perspective that modules are innately specified and develop as the child matures, relatively unaffected by the environment.
   • Karmiloff-Smith argued from a more constructivist perspective, asserting that modules are a result of development; a result of children interacting with a complex environment.
   • The empirical evidence is complex, but on balance supports the epigenetic view of theorists such as Karmiloff-Smith, that cognitive development is characterized by a process of modularization, rather than by a predefined structure of modularity.
   • Self-organization is a key concept in understanding how genes and environment can interact to affect the development of brain structures and their functions.      

Annotations:

• One set of tools relates to brain imaging – the creation of ‘functional’ maps of brain activity based on either changes in cerebral metabolism, blood flow, or electrical activity. Some of these imaging methods, such as PET, are of limited usefulness for studying changes in behavioural development in typically developing infants and children due to their invasive nature (requiring the intravenous injection of radioactively labelled substances) and their relatively coarse temporal resolution (whereby measurements are taken in chunks of minutes, rather than seconds).

1. (ERPs) - event-related potentials

   Annotations:

   • Event-related potentials involve using sensitive electrodes on the scalp surface to measure the electrical activity of the brain that is generated as groups of neurons fire at the same time These recordings can either be of the spontaneous natural rhythms of the brain electroencephalogram (EEG), or the electrical activity induced by the presentation of a stimulus
   • Recent developments of the ERP method allow relatively quick installation of a large number of sensors thus opening new possibilities in the investigation of infant brain function
   • ERPs suggest that processing of known words and control stimuli is initially spread over a relatively large area of cortex. This processing narrows to an area over the left temporal lobe only when the child’s vocabulary reaches about 200 words, irrespective of maturational age.
2. (fMRI)functional magnetic resonance imaging

   Annotations:

   • Functional MRI allows the non-invasive measurement of cerebral blood flow (Kwong et al., 1992), with the prospect of (a) millimetre spatial resolution, and (b) temporal resolution in the order of seconds. In other words, very accurate ‘maps’ of moment-by-moment brain activity can be built up. Although this technique has been used with children (Casey et al., 1997), the distracting noise and vibration, and the presently unknown possible effects of high magnetic fields on the developing brain, make its usefulness for healthy children under 4 or 5 years of age uncertain. However, there has been at least one fMRI study of infants initially scanned for clinical reasons

Annotations:

• This section extends the argument from Section 3. It looks in more detail at evidence relating to the question of whether specialist brain functions are genetically predetermined, or the result of a more epigenetic system in which genes and environment interact. We will focus on the case of language. Of all human abilities, language has been regarded as the most ‘biologically special’

1. PINKER

   Annotations:

   • Like Chomsky, Pinker can be characterized as a nativist. Indeed, the title of his book The Language Instinct (Pinker, 1994) already gives a strong indication of his theoretical perspective The ubiquity of complex language among human beings is a gripping discovery and, for many observers, compelling proof that language is innate. But to tough-minded skeptics ... it is no proof at all. Not everything that is universal is innate.
   1. The case for innateness of Lang.

      Annotations:

      • So Pinker acknowledges that in order to make the case for the innateness of language he must draw on several other lines of evidence. There are four basic components to Pinker’s argument: the existence of pidgins and creoles, observations regarding the so-called ‘poverty of the input’, the commonality of certain grammatical formulations across different languages, and evidence about brain structure and function.
      1. 1. Pidgins and creoles

         Annotations:

         • Pinker draws on the work of the linguist Derek Bickerton who studied the development of pidgins and creoles Pidgins (you may have come across the term ‘pidgin English’) are non-grammatical forms of communication that are cobbled together by adult speakers who share no common native language but who nevertheless learn to communicate. At the beginning of the twentieth century many migrant workers collected in Hawaii to work on booming sugar plantations. They developed a pidgin to communicate with each other. But the children who grew up in this pidgin-speaking community ended up speaking a fully fledged creole. A creole is a grammatical language, with all the structures and constructions of a ‘conventional’ language. According to Pinker’s interpretation of Bickerton’s work, the children simply could not help creating a grammatically well formed language, even though they had not been exposed to one. A similar effect can be observed in deaf children of hearing adults, or deaf children of deaf adults who learned sign language late in life. The sign language that the children are exposed to is like a pidgin; it is relatively ungrammatical and poorly structured. However, the children themselves learn a genuine sign language with all the grammatical complexities of any other language. In doing this, Pinker argues, the children of the immigrant communities and of the non-native signers, are actually doing no more than every child does – they are reinventing language anew as they use it. He sees this as compelling evidence for a language instinct:
      2. 2. Children & language not heard before

         Annotations:

         • Pinker gives the example of how children are able to produce grammatically correct questions, even though they will not have heard these questions asked before, and even though the rule that they have to follow is comparatively complex, and one that they are unlikely to have learned.
         • Turn the following statement into a question: ‘A unicorn is in the garden’. Can you devise a rule that you could follow to convert a statement like this into a question? Comment : You should have come up with something like ‘Is a unicorn in the garden?’ or ‘Is there a unicorn in the garden?’ The rule that you followed might have been ‘take the first ‘‘is’’ and move it to the beginning of the sentence, and add a question mark’. (Whether or not you added ‘there’ is not relevant to this activity.) Pinker’s and Chomsky’s observation is that children have no difficulty in formulating such questions, even though the rule they have to follow is not superficially easy, and despite probably never having heard such a construction before. ‘Surely not every child learning English has heard Mother say Is the doggie that is eating the flower in the garden?’ (Pinker, 1994, pp. 41–2). According to the nativists, children achieve the right grammatical form for the question because they have an innate grasp of the deep structure of language and its units of meaning.
      3. 3. Auxillary verbs

         Annotations:

         • The third element of Pinker’s argument is related to the second. Pinker asserts that many languages around the world use auxiliary verbs and that these languages move the auxiliary to the beginning of the sentence to formulate a question. (The ‘is’ in the sentences in Activity 4 is an English auxiliary verb.) If you think about it, there are limitless ways in which a question might be formulated. Why not turn the sentence backwards, or exchange the first and last words? So why have all these languages hit upon the same way of doing this? ‘It is as if isolated inventors miraculously came up with identical standards for typewriter keyboards or Morse code or traffic signals.’ (Pinker, 1994, p. 43). Pinker’s answer to this question is that it is not miraculous, and it is not a coincidence; rather, it reflects a commonality in the structure of the human brain.
      4. 4. The brain & Cog. Dev.

         Annotations:

         • The final and fourth part of Pinker’s argument brings us back to the specific topic of this chapter; that is, to studies of brain and cognitive development. He argues that there is ‘an identifiable seat [for language] in the brain, and perhaps even a special set of genes that help wire it into place

Annotations:

• One way of tackling the issue of innateness from the point of view of cognitive neuroscience is to ask whether there are any areas of cortex that are critical for language processing or acquisition. If there are such areas, without which language simply cannot happen, then a working assumption would be that these areas have an innate, language-specific processing capacity. If, on the other hand, there are a variety of cortical regions that can support language acquisition, then this would suggest that areas of language specialization emerge from more general structures, connectivity and processes within the developing brain, in concert with the rich language environment.
• Sometimes this debate is framed in terms of the concept of ‘equipotentiality’. This refers to the hypothesis that at birth the left and right hemispheres of the brain both have ‘equal potential’ for developing language. Evidence in favour of equipotentiality would seriously undermine the nativist case for innate language specific areas of the cortex. Bear in mind that in typically developing adults, areas of the left hemisphere are strongly associated with language processing, and damage to those areas in adulthood can cause a variety of lasting language difficulties. There is no doubt that by adulthood there are specialist cortical regions that are devoted to language processing (language modules). The question is whether language processing must be carried out by these areas, or whether early damage, or indeed atypical developmental pathways, (for example, 　 through deafness) can lead to other cortical regions performing the same functions. On balance, the evidence from neuroscientific studies points to the conclusion that several cortical regions are capable of supporting the development of language, but does not support the hypothesis of full equipotentiality.
• For example, Neville et al. (1998) used the fMRI technique (see Box 2, Section 3.1) to examine the brain regions that are involved in language processing in deaf and hearing participants. When the deaf participants viewed American Sign Language (ASL) sentences (see Figure 7b) they showed activation in language areas in the left hemisphere, as did the hearing participants on reading English sentences (see Figure 8a). However, the deaf participants (who were all native ASL signers) also displayed a level of activation in the right hemisphere that was not observed for the hearing participants
• Neville and her colleagues (Neville et al., 1992) also noted different patterns of cortical response (as measured by ERPs) in hearing and deaf participants whilst reading grammatically significant words in sentences, but noted similar patterns Semantic of response across the two groups when they were reading semantically To do with important words. So perhaps the question of how biologically special language is meaning. may require different answers for different aspects of language processing and acquisition. Neville et al.’s findings indicate that grammatical aspects of language may be more sensitive to experience than semantic aspects, because hearing and deaf participants (who have a different experience of language) responded in different ways to the grammatical information. After summarizing a decade of their research, Neville and Bavelier conclude that the evidence supports the hypothesis that ‘there are constraints on the organisation of the neural systems that mediate formal language ... however, it is clear that the nature and timing of sensory and language experience significantly affect the development of the language system of the brain
• Further evidence to support the hypothesis that different areas of the cortex are capable of supporting language processing comes from studies of children with localized brain damage (focal lesions) that happened either before or during birth. In a sample of children aged between 3 and 9 years, Reilly and colleagues (Reilly et al., 1998) found that the group of participants with a focal lesion performed worse on a series of language tasks than the group of typically developing control participants (see Research summary 1). However, the children with a focal lesion showed a pattern of catching up on these measures, then lagging behind at the next stage of language development, then catching up again. The crucial points here are: first, functional recovery from a focal lesion appears to be an ongoing process in childhood, and second, there is an implication that functions affected by the original damage to a localized area of the cortex were taken over in later development by undamaged areas of the cortex.
• The evidence presented in this section does not in itself rule out the proposition that the left hemisphere is innately ‘pre-wired’ for language. It only shows that other areas of the brain can ‘do’ language, if necessary. However, there is a proposition that fits the evidence a little more securely than this. This is that the architecture and connectivity of the left temporal lobe (the region most clearly related to language processing in adults) biases the system towards building neural modules that specialize in language processing in these regions. These regions may be slightly better suited to processing rapidly changing information than other areas of the cortex, and so can develop more efficient computational properties for processing language. However, the regions are not the only place where language processing can find a home. There is sufficient plasticity in the developing child’s cortex to enable other regions to take on these functions, perhaps with some loss of efficiency. ‘While regions of the left temporal lobe may be best suited to language processing, they are not critical since language can develop in a close to normal way without [them]’ (Johnson, 1997, p. 141). Overall, therefore, the evidence from developmental cognitive neuroscience supports a compromise position somewhere between equipotentiality on the one hand, and genetically predetermined language-specific cortical regions on the other.

1. Review of Innateness and Cog. neuroSc.

   Annotations:

   • Where does this leave the arguments of Chomsky, Pinker and the nativists? In some respects, the evidence from developmental cognitive neuroscience supports their position. There is clearly some kind of predisposition in human infants to develop language. Even if there is damage to some of the brain structure that typically goes on to support language in adults, the plastic, self-organizing infant brain will find another way of dealing with it. As Pinker says, children cannot help but develop language. However, the fact that early damage to structures that usually go on to develop language can be overcome suggests that there are general properties of brain structure and connectivity that are suited to processing language, without being pre-specified to do so.
   • Furthermore, if one region of the cortex always went on to support language, it could be argued that it is innately predetermined to do so. But if, as you have seen, other regions can support language when necessary, then this suggests that there is some other factor that influences the development of these brain regions, above and beyond an innate blueprint. If the fate of these regions has not been determined by a genetic blueprint, then what else is there to feed into the equation? The answer is, surely, the environment; specifically, the child’s language environment. These regions have genetic constraints on what they can and cannot do, in terms of innately pre-specified principles of neural connectivity and structure. But within these constraints the different cortical regions can selforganize through interaction with a complex environment to develop their ultimate cognitive function. All this takes us back to the argument of Section 3 in favour of the epigenetic basis for the development of specialized cognitive modules. It suggests that both in typical and atypical development, what drives the development of brain function is a potent mix of genes and environment, and that specialist cognitive modules are a product of development. This is a rather more constructivist position than the one adopted by Chomsky and Pinker.
   1. Summary

      Annotations:

      • . Pinker and Chomsky are key advocates of the nativist position on language development, which prioritizes the role of genetic determination. . In support of his case, Pinker uses arguments from (a) the development of pidgins into creoles, (b) the ‘poverty of the input’, (c) the universality of potentially arbitrary grammatical rules, and (d) neuropsychology. . Equipotentiality is an epigenetic proposition that the left and right hemispheres are equally equipped for language development at birth. . Evidence from developmental cognitive neuroscience suggests that there is sufficient plasticity in the infant’s brain to enable several regions of cortex to support language development and processing.

Annotations:

• The region of the frontal lobe in front of (‘anterior to’) the primary motor and premotor cortex, the prefrontal cortex (see Figure 1), accounts for almost onethird of the total cortical surface in humans and is considered by most investigators to be critical for many higher cognitive abilities (Milner, 1982; Goldman-Rakic, 1987; Fuster, 1989). The types of cognitive processing that have been associated with the prefrontal cortex concern the planning and execution of sequences of action, the maintenance of information over short delays in working memory, and the ability to inhibit a set of responses that are appropriate in one context but not another. Collectively these cognitive processes are known as ‘executive function’. The prefrontal cortex is the part of the brain that shows the most prolonged period of postnatal development, with changes in synaptic density detectable even into the teenage years (Huttenlocher, 1990). For this reason it has been the part of the brain most frequently associated with cognitive development.

1. Relating structural change to cognitive development

   Annotations:

   • One approach to understanding the relationship between cognitive development and structural developments in the prefrontal cortex is to chart advances in cognitive abilities at a given age, and to try to relate these advances to observed changes in the prefrontal cortex. Does the emergence of a particular ability happen at the same age as an observed change in brain structure? (Bear in mind that if a change in cognitive ability does occur at the same time as a change in brain structure, this does not necessarily mean that the two things are directly
2. The prefrontal cortex and the acquisition of new skills

   Annotations:

   • An alternative perspective on the role of the prefrontal cortex in cognitive development has been proposed by several researchers who have suggested that the region may play a role in organizing other parts of cortex (for example, Thatcher, 1992), and that it plays a critical role in the acquisition of new knowledge and skills. According to this view, regions of the prefrontal cortex play an important role in the early stages of the development of a new skill. As mastery of the skill increases, so involvement of the prefrontal cortex decreases, and other specialist areas of cortex take over. The processing resources of the prefrontal cortex are then switched to some other newly developing skill. In contrast to the perspective presented in Section 5.2 this view leads to the prediction that the involvement of the prefrontal cortex in a particular task or situation will decrease with increased experience or skill in the domain.
   • Two recent lines of evidence are consistent with the view that regions of prefrontal cortex play a key role during the earlier stages of skill acquisition during infancy. Johnson and colleagues (1998) studied infants with localized damage to parts of their cortex in a visual attention task. They found that only infants with damage in the prefrontal regions of cortex were impaired on the task. In adults one would expect those with damage to parietal regions (see Figure 1, p. 118) to show such an impairment. Similarly, a recent study involving visual attention and eye movement planning in infants showed suggestive evidence of prefrontal cortex involvement (Csibra et al., 1998). The same effect was not observed in adults.
   • The findings from the Johnson et al. (1998) study, and from Csibra et al. (1998) are consistent with the view that the cortical regions that are crucial for a particular ability change with the stage of acquisition of that ability. Perhaps there is greater prefrontal activity on visual attention tasks in infancy than in adulthood because infants are still at an early stage of developing visual attention skills. By adulthood the skills have been learned and have ‘moved’ to a different, more specialized area of the cortex.
3. A note on relating brain structure and function

   Annotations:

   • Section 5 has been about efforts to bridge the conceptual gap between brain structure (how the different regions of the brain are physically organized) and function (what these regions do). This is a major challenge for developmental cognitive neuroscience. Much is known about the brain at a structural level. Much is also known about behaviour and cognition. But there is still a great deal to learn about how structures underpin behaviours and cognitive functions, and about how behaviours and cognitive functions influence the development of structures. One tool for investigating the relationship between structure and function in this respect is connectionist computational modelling (neural networks). One aim of connectionist modelling is to see how the brain structures that we know about could possibly give rise to human behaviour and cognition.
4. SUMMARY

   Annotations:

   • . The prefrontal cortex is associated with higher cognitive functions, and because of its prolonged postnatal development, it is the area of the brain most closely associated with cognitive development. . There is evidence to suggest that developments in the prefrontal cortex are associated with the developing abilities of the infant, as measured by performance on object permanence tasks. . Alternatively, the prefrontal cortex may play a more organizing function with respect to cognitive development, and its role in the acquisition of skills may diminish as other more specialist cortical regions take over. . Linking cortical development to cognitive and behavioural development is a complex, inexact process. Connectionist computational models are one set of tools for trying to bridge the gap.
   1. Conclusion

Annotations:

• Before engaging with the question of how young children acquire grammatical understanding, it is first necessary to appreciate the complexity and the significance of spoken language as a structure. When people speak, they are producing and combining sounds to communicate their ideas. The capacity to combine sounds in different ways enables the speaker to communicate different ideas. The capacity to combine sounds in novel ways enables the language user to communicate ideas that have never been expressed before. So, the creative use of language is entirely dependent on the ability to assemble simple building blocks of sound into the complex structures we call sentences. Speakers of a language appreciate the organization of their systems of linguistic combination. They recognize when a sentence is spoken incorrectly, say by a child or a foreigner. Speakers can even classify the type of mistake in an erroneous utterance. For example, they may comment that it was not correctly pronounced, that it contained an unknown word, or that it was grammatically incorrect. See Box 1 for a reminder of some grammatical terms.

1. Phonology The structure of speech sounds

   Annotations:

   • Phonology and phonotactics are terms that are used to refer to the knowledge that a speaker possesses about the sound patterns of his or her native language. For example, in English, speakers readily distinguish sounds like [b] as in ‘bat’ from sounds like [p] as in ‘pat’, whereas Arabic speakers ignore this distinction.
   • Likewise, there are combinations of sounds that English speakers would regard as ‘foreign’. For example, the /p/ sound cannot be followed by the /s/ sound at the beginning of a word in English but it is permitted in French. So, in the English word ‘psychology’, the letter ‘p’ is silent, but in the French word ‘psychologie’ the /p/ and the /s/ sounds are both pronounced. Speakers who are not careful in articulating these subtle cues, or listeners who do not pay attention to them, are likely to be misunderstood or to misunderstand the communications of others. Indeed, as you saw in Chapter 2, much of language development during the first year of life is concerned with mastering the mechanics of speech production, or deciphering the sound patterns of the language that dominate the infant’s acoustic environment.
2. Morphology The structure of words

   Annotations:

   • Morphology is the term used to refer to the knowledge a speaker possesses regarding the manner in which new words can be created from existing words or other meaningful units of language. There are many aspects to morphology, so we will introduce you to just two here for the purposes of illustration. The first of these is known as compounding. This is the combinatorial capacity in a language whereby two existing words are glued together to form a new word. For example, in English the nouns ‘lady’ and ‘bird’ can be combined to form the new word ‘ladybird’. Sometimes, as with this example, the meaning of the new word is not predictable from its origins. In other cases, the meaning of the newly created word is more transparent, like ‘lighthouse’.
   • Young children frequently demonstrate sensitivity to morphology in the way that they invent their own compound words that are meaningful to them. For example, one child that we know spontaneously invented the noun ‘moregranny’ to refer to one of her grandmothers, and to differentiate her from her other ‘granny’. The logic of ‘granny’ and ‘moregranny’ is undeniable and appealing, and all the more remarkable because this shows us that children are not merely imitating what they hear adults saying: they are generating their own ideas about the rules that govern how language is constructed.
3. Syntax The structure of sentences

   Annotations:

   • Syntax is the term used to refer to the knowledge that a speaker possesses regarding the manner in which words can be combined to form sentences. In English, syntax provides the information needed to determine who did what to whom. For example, English speakers have no difficulty distinguishing the meanings of the two sentences:
4. Grammatical morpheme

   Annotations:

   • Language users exploit another combinatorial device in which existing words are joined together with other sounds that do not have meaning in-and-of themselves. These other sounds, referred to as grammatical morphemes, modify the meaning of the words with which they combine: the morpheme /s/ in the word ‘boys’ indicates plurality (more than one boy); the morpheme /ed/ in the word ‘kicked ’ indicates that the action was performed in the past. The use of grammatical morphemes such as word endings in this way is known as inflection.
5. CHOMSKY & PINKER ON LANG.

   Annotations:

   • An alternative solution is that young children already ‘know’ that languages can be syntactically or morphologically oriented. That is, they are born with an implicit understanding that languages can signal who did what to whom through syntactic or morphological devices. In Chapter 3 you were introduced to the idea of language development being underpinned by an innate predisposition to acquire it; a position advocated by the work of Noam Chomsky, and further developed by Steven Pinker. With respect to acquiring grammatical understanding, Chomsky (1965) argued that humans have an innate knowledge of potential language structures, which he refers to as Universal Grammar. Universal Grammar contains a set of constraints on language processing that can be switched on or off through exposure to spoken language. Languages which exploit morphological cues ‘switch on’ the morphological constraints, whilst those which exploit syntactic cues switch on the syntactic constraints.
   • Chomsky argued that this kind of innate knowledge is necessary because children are rarely presented with coherent, grammatically complete speech that maps directly onto things happening in their immediate environment. For example, speakers might say a variety of different things in the context of such as ‘Look’ or ‘Not him again’, or the conversation may be about something that happened in the past that the child knows nothing about. How are children to know which are the important parts of language to focus on? Chomsky’s answer to this question is that it is Universal Grammar that directs the child’s linguistic attention to the right kind of information.
6. SUMMARY

   Annotations:

   • . Phonology refers to the knowledge that a speaker possesses about the sound patterns of his or her language. . Morphology refers to the knowledge a speaker has about the manner in which new words can be created from meaningful units of language, such as words, and grammatical morphemes. . Syntax refers to the knowledge a speaker has about the ways in which words may be combined to form sentences. . Languages differ in the extent to which they rely on either morphology or syntax to indicate who did what to whom. . English speaking children pass through a U-shaped pattern of development in their understanding of morphology. This is where they 　 initially produce grammatically perfect utterances, and then pass through a period of making errors, before eventually regaining high levels of accurate language production. . Universal Grammar refers to the idea that children may have an innate cognitive mechanism that represents ‘knowledge’ of how languages can be constructed. Through linguistic exposure, constraints that relate to their language are ‘switched on’ and others that do not apply are ‘switched off’.