Developmental psychology - summary of chapter 10 of an Introduction to Developmental psychology by A. Slater and G. Bremner (third edition)

Developmental psychology
Chapter 10
The development of language

What is human language?

A communication system

Human language is primarily a communication system, a means for speakers of a language to communicate with one another.
This ability is not unique to the human species.
But non of the communication systems of other species have been found to possess all of he characteristics found in human communication.
Human language is a symbolic, rule-governed system that is both abstract and productive, characteristics that enable its speakers to produce and comprehend a wide range of utterances.
It evolved from multiple abilities.

A symbolic system

Words and parts of words represent meanings.
These symbols refer to things other than themselves. They are conventional because speakers of a language use the same word to express the same meanings. This makes communication possible.
Language symbols are arbitrary, there is no necessary relation between sound and meaning.

A rule-governed system

Each human language is constrained by a set of rules that reflects the regularities of the language.
The rule system is abstract, it goes beyond the simple association of individual words and instead involves the manipulation of abstract classes of words.
Articles precede nouns.
The abstract classes and rules enable a languages productivity.

Language is productive

A finite number of linguistic units and a finite number of rules are capable of yielding an infinite number of grammatical utterances.
Speakers may produce and comprehend novel utterances.
Language also makes it possible to discuss fantasies and hypothetical situations and events.

The development of the pragmatic system

Turn-taking

Conversations take place when participants take turns responding to each other’s queries or statements.

Mother-infant interactions

Turn-taking behavior makes its first appearance in the earliest interaction between mothers and infants.
Nursing sometimes involves an early non-verbal type of turn-taking.
Touching and vocalizations are two modalities in which exchanges between mothers and their infants takes turns.

Proto-conversations: interactions between adults and infants in which the adults tend to vocalize when the infants are not vocalizing, or after the infant has finished vocalizing.

Between 8 and 12 months, infants begin to take a more active role in turn-taking.
The dyadic proto-conversations evolve into triadic interactions
Proto-imperatives: when infants point to an object and then alternate their gaze between the object and the adult until they obtain the desired object.
Proto-declarative: when infants use pointing or looking to direct an adult’s attention toward an object.
These actions allow infants to communicate their intentions more clearly while also facilitating their ‘conversations’ with others.

Imitation

Turn-taking is involved in infant’s imitation of others.
Very young infants are capable of imitation. Explanation: mirror neuron.
Imitation in various play activities is an important precursor to the development of language.
Children frequently use imitation in their conversations with other children or adults. Imitation allows children to take a turn by repeating all or part of what the speaker has just said.

The average 2 year old takes only one or two turns per conversation.
3 to 5 year olds are able to engage in conversation that contain as many as 12 turns.

Imitation may be a means by which children learn to increase the number of turns that they take in a conversation.

Initiating interactions

Infants must learn to initiate interactions.
Infant’s first attempts to initiate interactions with an adult often focus on directing the adult’s attention to the infant or to an object. These are typically non-verbal. Pointing.
As children learn to respond to the points of others, they also learn to better direct the attention of others.
Between 12 and 18 months, infants learn to coordinate gestures, looks and vocalizations in order to communicate their intents and wants to others.
As children acquire language, their attempts to initiate interactions become more verbal and less gestural.
Infants incorporating gestures at earlier ages predicts future language development.

Children younger than 2 years tend to talk about things that exist in there here and now. They are most likely to refer to familiar and visible objects or people.
As their language skill increase, children come to discus a much broader range of topics.

Maintaining conversations

Turn-taking is an important aspect of conversation maintenance.
Young children are likely to interrupt others, and so disrupt the conversational flow.

Children also must learn to add relevant information to the dialogue.
Young children are likely to use their turns to refer to something completely different form the topic at hand. This is even true if children are asked questions.
Children under age 2 typically answer only a third of the questions posed to them.
By 3 years children answer more than 50 per cent of the question they are asked.
Children are more likely to respond to questions than they are to ask questions.

Young children’s conversation with peers contain high proportions of imitations, repetitions and sound play.
If the conversation topic is that is familiar to both children, even young children are able to sustain meaningful conversations.

Repairing faulty conversations

Children must learn when and how to repair conversations as mis-conversations occur.
In order to repair a miscommunication, one must both realize that a miscommunication has occurred and understand how to correct the problem.

Children as young as 1 year sometimes appear to recognize the failure of their non-verbal communicative attempts. In such a case, the infants seems to be trying to repair the communicative failure by repeating the pointing.
Young children learn to use repetition to correct faulty communications.
As they get older, children add revisions and substitutions to their increasing repertoire of strategies for repairing and maintaining conversations.

Adults play an important role in the development of this aspect of the pragmatic system.
They often request children to repeat utterances or to clarify the portion of the conversation that they did not understand.

By 3 years, children have learned to request clarification of messages that they do not understand.
As children become more proficient users of their language, they learn to more clearly question specific aspects of other’s messages.

Children have learned many of the aspects of the pragmatic system before their fifth birthday. Pragmatic skills are based on the acquisition of other aspects of their mother tongue, including the phonological system, the syntactic system and the semantic system.

The development of the phonological system

Phonology is the aspect of language concerned with the perception and production of sounds that are used in language.

Speech perception

Speech segmentation

Deciphering the sounds of the language that they hears should be a formidable problem for infants.
They are exposed to an undifferentiated speech stream.
Children must separate the speech stream into individual sounds and sound combinations in order to learn the relevant sounds of their language.

Despite the inherent difficulty of the task, infants do learn to divide or segment the speech stream into meaningful units.
Their attempts to do so may be facilitated by the nature of the speech that adults direct to infants. It has a higher pitch, more exaggerated pitch contours, a larger pitch range and is more rhythmic.
This is infant-directed speech or motherese.
By 7 months, infants are able to recognize familiar words in an uninterrupted speech stream. They are also able to remember the words that they have segmented.
Young infants seem to use a variety of cues to determine when words begin and end in the speech stream, including strongly stressed syllables to indicate the onset of new words.
Infants prefer to listen to human speech than to other sounds in their environment, which may also facilitate the difficulty task of segmenting speech.

The ability to segment speech is a critical component in language acquisition.

Categorical perception of speech sounds

Phonemes: the smallest unit of speech that can affect meaning.
A set of sounds that are not physically identical to one another, but which speakers of a language treat as equivalent sounds.
Human languages differ in terms of the number and types of phonemes that they employ.

Infants discriminate between phonemes.

The ability of infants to discriminate phonemes has considerable implications:

• Young infants engage in the categorical perception of speech sounds
• Categorical perception may be an innate mechanism of interpreting sounds. The mechanism may rest on general auditory processing skills rather than on skills specific to human speech. Infants may be predisposed to categorize sounds which then may influence their perception of speech sounds.

Becoming a native listener

The human ability to discriminate possible phonemes diminishes with age.
At 6 months, infants are able to discriminate a wide range of phonemes. The discriminative capabilities are influenced with experience.
8 month olds will use information with which they are already familiar to help discriminate new sounds.
12 months, infants remain able to discriminate the phonemes of the language they are learning, but are unlikely to discriminate the phonemes of other languages.

Children’s acquisition of the phonemes of their native language depends on both the innate predisposition for categorical perception of sounds and experience with sounds used as phonemes in their native language.

Speech production

The ability to produce speech sounds lags behind the ability to perceive the same sounds.

Reflexive vocalizations (0-2 months)

Reflexive vocalizations: the first sounds produced by infants.
During the first month of life, infants produce more than one type of cry, raising the possibility that different infant cries might mean different things.
These cry types are characterized by different mean fundamental frequencies, durations and compositions of sounds.
If parents are asked to discriminate their young infant’s cry types, they are unable to do so if the cry is recorded and played back to them in the absence of external context.
The characteristics of cries do change in response to the experience of various emotions and context, and individuals do respond physiological to these changes.

Cooing and laughing (2-4 months)

Infants begin to laugh and to combine sounds with one another.
The coo sound emerges toward the end of the second month of life.
The reciprocal cooing between infant and parent may help the infant to learn that communication involves taking turns.

Babbling and vocal play (4-6 months)

Babbling: the first types of controlled vocalizations produced by infants typically between 4 and 6 months of age.
As they gain control over their vocal cords, lips, tongue and mouth, infants begin to produce a wide range of sounds and sound combinations.

Canonical babbling (6-10 months)

Canonical: the usual, normal, or natural state of things. Canonical babbling is babbling sounds made by the infant around 6-10 months, when vowels and consonants are combined in such a way that they sound like words.
There is no evidence that infants actually attach meaning to these sound combinations.
During this period, infants continue their experimentation and play with sounds.
Babbling is a universal phenomenon that seems to be genetically determined.
Infants tend to babble during the same age period and to produce a similar range of sounds during early babbling.
Neither hearing human speech nor having others respond to infant vocalizations are necessary for early babbling to occur.

Vocal babbling is rare in deaf infants older than 7 months, suggesting that hearing speech sounds play in an important role in the continuation of babbling past its early stages.

Manual babbling: the manual equivalent of vocal babbling which is found in deaf children and hearing children learning to sign.
Proposition: a manual communication system may have evolved before our vocal-based system.
Gestures are critical to language development, which may also be related to the development of motor abilities.

Some form of interaction is important for maintaining the infant’s efforts to produce language sounds or gestures.

Modulated babbling (10 months on)

The final period of babbling and language play.
Characterized by a variety of sound combinations, stress and intonation patterns, and overlaps with the beginning of meaningful speech.
May play an important role in the acquisition of the intonation patterns that are important for the infant’s native language.

The development of articulation

Children are more likely to use words that they can pronounce.
As children learn to produce correct pronunciations, they may produce phonological distinctions that adults cannot perceive.
Children are aware that their incorrect pronunciations differ from those of adults, and at least some children’s pronunciations that are viewed as equivalent by adults may be functionally distinct for children.
We do not know if children are aware of how their pronunciations differ from those of adults, nor do we know the manner in which children’s and adult’s representations of pronunciations are related.

The development of the syntactic system

Syntax: the manner in which words and parts of words are related to one another to produce grammatical sentences: the production of sentences is governed by grammatical structures and rules.

S-structure: the syntax of a sentence. One s-structure can have more than one meaning. In order to understand the intended meaning of a sentence, one must examine the d-structure.

D-structure: the abstract representation of a sentence, or the actual meaning that the sentence is trying to convey.

The one-word period

Children’s acquisition of syntax follows a relatively predictable pattern during the first two years of life.
Between 10 and 18 months, children begin to produce single word utterances. First words generally include people-based terms, followed by nouns.

What’s in a word?

Most adults interpret children’s single-word utterances as if they mean more than the literal single word. Those are assumptions.
The implication of the one-word period for syntactic development is unclear.
Children comprehend more than they can produce. They understand at least some aspects of word order.

The two-word period

18-24 months, most children begin to produce two words at a time.
These words are not chosen randomly. Children consistently use the words that convey the most meaning.
Children’s language environment increases the likelihood that they first learn and use high meaning words. Such words are more likely to be stressed in adult speech, and so are perceptually salient compared to other words.
Children are also more likely to verbally produce words that they have initially produced as gestures and are faster in producing two-word combinations if they had previously combined a gesture with a word.

Word order

Children’s knowledge of language and their use of this knowledge are limited during the two-word period.
Children’s use of consistent word order seems to reflect limited knowledge rather than general rules.
The manner in which speech in the two-word period is related to later syntactic development is a matter of considerable debate.

Later syntactic development

Children’s syntactic knowledge increases dramatically following the two-word period, resulting in rapidly improving language skills.
The child’s utterances are longer (the average number of morphenes) and more complex words are used.
Children learn to use a variety of linguistic forms and structures relatively quickly in the months following the two-word period.

The significance of overregularization errors and creative generalizations

Overregularization: when a previously learned rule is applied in the wrong situation.
Children are using the rules of the language they are learning to produce novel words.
The extend to which children generalize the rules that they are learning depends on the ease of the language they are learning.

Plurals

Soon after children begin to produce correct regular plural forms (like dogs) they also begin to produce overregularised forms (like foots or mans).
These errors demonstrate that children have acquired a regular plural rule, but have not learned all the exceptions to the rule.
Children can distinguish nouns that refer to countable objects from nouns that refer to entities that cannot be counted.

Past tense

Children overregularise their use of -ed.

Creative overgeneralisations

Children (and adults) occasionally create new verbs by treating a noun as if it were a verb.

How can syntactic development be explained?

Innate knowledge?

Chomsky
Arguments:

• Language requires the ability to relate d-structures to s-structures
• The environment only provides children with information about s-structures.
• The sentences that children hear are complex and often ungrammatical
• Children receive little feedback about the grammatical correctness of their utterances.
• Children acquire their first language relatively quickly and easily.

Do parents correct their child’s language?

Parents are unlikely to correct their children’s ungrammatical utterances. They may actually reinforce ungrammatical utterances.
Parents sometimes correct grammatical sentences because the meaning of the sentence is incorrect even thought the syntax is perfect.
Even when parents make a conscious effort to correct their child’s ungrammatical constructions, they often encounter a resistant child.

Children imitate some of the speech that they hear.
The parent’s role in providing models is an important one.

The language input to the child.

Parents do a much better job of providing children with good examples of grammatical sentences than Chomsky supported.
Mothers produced ungrammatical sentences less than one-tenth of 1 per cent of the time that they spoke to their young children.
Parents usually speak to young children in short grammatical sentences. Even 4 year olds simplify the speech they direct to children younger than themselves.

No matter how simple the language input to the child is, it consists of s-structures. D-structures must be innate (Chomsky). The role of experience is to provide information about s-structures. This information will be combined with the child’s innate knowledge of language to yield the particular grammatical rules for the language the child is learning.

Children are born with a very string predisposition to learn a language, this does not mean that children are born with innate knowledge of a language.
The speed and accuracy with which children acquire and produce various utterances suggests that some innate component must be present.

Acquisition of word meaning

Comprehension: in language development, the language children can understand, distinguished from production.
Comprehension almost always exceeds production.

Young infants are learning the meaning of at least some of the words in their environment.
Before their fourth birthday, children will learn to use words to represent and refer to real, possible and imaginary aspects of their world.

Guessing a word’s meaning

The child’s interpretation and memory of the situation in which the word was first encountered determined the child’s initial guess about the word’s meaning.
The manner in which a child interprets a recently discovered word depends on the child’s existing semantic system, their knowledge of the world, the level of their cognitive skills and their ability to selectively attend to other’s cues.

Initially, children build their vocabulary by focusing on one-to-one correspondences between words and things. But there are many possible interpretations for every situation.

Overextension: extending the meaning of a word too broadly.

Underextension: extending the meaning of a word to too few instances.

The complexity of the task.

Children make relatively few mistakes attaching meaning to words, given the complexity of the task.

• Words occur in situations that may be interpreted in numerous ways
• Many things may be referred to with a variety of words and linguistic forms
• Some categories are part of larger categories
• Many words have more than one meaning

Children construct a vocabulary of approximately 14000 words by the time they are 6 years old.

As children gain additional experience with a word and its uses, they must compare recently acquired information with what they have already stored in their semantic system.

Is children’s acquisition of word meaning constrained?

Constraints that influence word meaning development:

• Whole object constraint:
  Assumes that children believe that words refer to whole objects rather than to parts of objects.
• Mutual exclusivity constraint:
  Assumes that children believe that there is a one-to-one correspondence between meanings and words.

But there is little evidence.
It also may not be language specific, but more related to attention and learning mechanisms.

The importance of semantic relations

Children construct a semantic system rather than a list of independent words, because words are related to one another.
The development of he semantic system is facilitated by children’s acquisition of semantic relations.
Children must learn that objects can be referred to by more than one word. The child must determine how words relate to one another.

Semantic dimensions

The end points of semantic dimensions seem to be more salient to young children than are points between the two extremes.
As children discover the semantic relations that are necessary to structure their semantic system, they are better able to organize their growing vocabulary.

The interaction of language and cognitive development

Before children begin to acquire words, they have formed concepts of the world.
Children’s first words are most likely to be those that express these early concepts because children search for ways to communicate what they know.
Even the early development of the semantic system results in change in children’s concepts.

Two strategies when faced with gaps in the semantic and/or conceptual system:

• Acquiring a new word:
  When acquiring a new word, search known concepts in case the word denotes a previously acquired concept. In no existing concept seems appropriate, attempt to construct a new one.
• Acquiring a new concept
  When acquiring a new concept, attempt to attach a known word to it. If no word seems appropriate, look for one.

The development of the semantic system influences conceptual development by virtue of the manner in which language dissects and organizes the world.