What is language, and how does it develop?

Introduction

Language is a system of arbitrary symbols that can be combined in conventionalized ways to express ideas, thoughts, and feelings. Language has been typically seen as uniquely human, separating the human species from other animals. Language enables people of all cultures to survive as a group and preserve their culture. The fundamental features of human language make it extremely effective and very economical. Language uses its arbitrary symbols to refer to physical things or nonphysical ideas; to a single item or a whole category; to a fixed state or to a changing process; to existent reality or to nonexistent fiction; to truths or to lies.

Language is systematic and rule-governed. Its four component subsystems are phonology, semantics, grammar, and pragmatics. The phonological system uses phonemes (the smallest speech sound units capable of differentiating meanings) as its building blocks to form syllables and words through phonemic rules. For example, /m/ and /n/ are two different phonemes because they differentiate meaning as in /mĪt/ (meat) versus /nĪt/ (neat), and “meat” has three phonemes of /m/, /Ī/, and /t/ placed in a “lawful” order in English to form one syllable. The semantic system makes language meaningful. It has two levels: Lexical semantics refers to the word meaning, and grammatical semantics to the meaning derived from the combinations of morphemes (the smallest meaning units) into words and sentences. “Beds,” for example, has two morphemes, “bed” as a free morpheme means “a piece of furniture for reclining or sleeping,” and “s” as a bound morpheme means “more than one.”

The grammatical system includes morphology and syntax. Morphology specifies rules to form words (for example, prefixes, suffixes, grammatical morphemes such as “-ed,” and rules to form compound words such as “blackboard”). Syntax deals with rules for word order in sentences (such as, “I speak English,” but not “I English speak”). Furthermore, the syntax of human language has four core elements, summarized in 1999 by Edward Kako as discrete combinatorics (each word retains its general meaning even when combined with other words), category-based rules (phrases are built around word categories), argument structure (the arguments or the participants involved in an event, labeled by verbs, are assigned to syntactic positions in a sentence), and closed-class vocabulary (the grammatical functional words, such as “the,” “on,” or “and,” are usually not open to addition of new words).

The fourth subsystem in human language is the pragmatic system. It involves rules to guide culture-based, appropriate use of language in communication. For example, people choose different styles (speech registers) that they deem appropriate when they talk to their spouses versus their children. Other examples include the use of contextual information, inferring the speaker’s illocutionary intent (intended meaning), polite expressions, conversational rules, and referential communication skills (to speak clearly and to ask clarification questions if the message is not clear).

Language is creative, generative, and productive. With a limited number of symbols and rules, any language user is able to produce and understand an unlimited number of novel utterances. Language has the characteristic of displacement; that is, it is able to refer to or describe not only items and events here and now but also items and events in other times and places.

Language Acquisition and Development

Views on language acquisition and developmentare diverse. Some tend to believe that language development follows one universal path, shows qualitatively different, stage-like shifts, proceeds as an independent language faculty, and is propelled by innate factors. Others tend to believe in options for different paths, continuous changes through learning, and cognitive prerequisites for language development.

A Universal Pathway in Language Development

Stage theories usually suggest a universal path (an invariant sequence of stages) for language development. A typical child anywhere in the world starts with cooing (playing with the vowel sounds) at two to three months of age, changes into babbling (consonant-vowel combinations) at four to six months, begins to use gestures at nine to ten months, and produces first words by the first birthday. First word combinations, known as telegraphic speech (content word combinations with functional elements left out, such as “Mommy cookie!”), normally appear when children are between 1.5 and 2.5 years. Meanwhile, rapid addition of new words results in a vocabulary spurt. Grammatical rules are being figured out, as seen in young children’s application of regular grammatical rules to irregular exceptions (called over-regularization, as in “I hurted my finger”). Later on, formal education promotes further vocabulary growth, sentence complexity, and subtle usages. Language ability continues to improve in early adulthood, then remains stable, and generally will not decline until a person reaches the late sixties.

Different Pathways in Language Development

Although the universal pattern appears true in some respects, not all children acquire language in the same way. Analyses of young children’s early words have led psychologists to an appreciation of children’s different approaches to language. In her 1995 book Individual Differences in Language Development, Cecilia Shore analyzed the different pathways of two general styles (sometimes termed analytic versus holistic)
in the four major language component areas.

In early phonological development, holistic babies seem to attend to prosody or intonation. They tend to be willing to take risks to try a variety of sound chunks, thus producing larger speech units in sentence-like intonation but with blurred sounds. Analytic babies are phonemic-oriented, paying attention to distinct speech sounds. Their articulation is clearer.

In semantic development, children differ not only in their vocabulary size but also in the type of words they acquire. According to Katherine Nelson (cited in Shore’s work), who divided children’s language acquisition styles into referential versus expressive types, the majority of the referential babies’ first words were object labels (“ball,” “cat”) whereas many in the expressive children’s vocabulary were personal-social frozen phrases (“Don’t do dat”). In Shore’s opinion, the referential babies are attracted to the referential function of nouns and take in the semantic concept of object names; the expressive children attend more to the personal-social aspect of language and acquire relational words, pronouns, and undifferentiated communicative formulaic utterances.

Early grammatical development shows similar patterns. The analytical children are more likely to adopt the nominal approach and use telegraphic grammar to combine content words but ignore the grammatical inflections (such as the plural “-s”). The holistic children have a tendency to take the pronominal approach and use pivot-open grammar to have a small number of words fill in the frame slots (for instance, the structure of “allgone [ . . . ]” generates “allgone shoe,” “allgone cookie,” and so on). The units of language acquisition might be different for different children.

In the area of pragmatic development, children may differ in their understanding of the primary function of language. Nelson has argued that the referential children may appreciate the informative function of language and the expressive children may attend to the interpersonal function of language. The former are generally more object-oriented, are declarative, and display low variety in speech acts, whereas the latter are more person-oriented, are imperative, and display high variety in speech acts.

Convenient as it is to discuss individual differences in terms of the two general language acquisition styles (analytic versus holistic), it does not mean that the two are necessarily mutually exclusive—children actually use both strategies, although they might use them to different extents at different times and change reliance patterns over time.

Theories of Language Development

With an emphasis on language performance (actual language use in different situations) rather than language competence (knowledge of language rules and structure), learning theories contend that children learn their verbal behavior (a term suggested by the behaviorist B. F. Skinner in 1957 to replace the vague word of “language”) primarily through conditioning and imitation, not maturation. Classical conditioning
allows the child to make associations between verbal stimuli, internal responses, and situational contexts to understand a word’s meaning. It also enables the child to comprehend a word’s connotative meaning—whether it is associated with pleasant or unpleasant feelings. Operant conditioning shapes the child’s speech through selective reinforcement and punishment. Adults’ verbal behaviors serve as the environmental stimuli to elicit the child’s verbal responses, as models for the child to imitate, and as the shaping agent (through imitating their children’s well-formed speech and recasting or expanding their ill-formed speech).

Nevertheless, learning theories have difficulty explaining many phenomena in language development. Imitation cannot account for children’s creative yet logical sayings, such as calling a gardener “plantman,” because there are no such models in adult language. Shaping also falls short of an adequate explanation, because adults do not always correct their children’s mistakes, especially grammatical ones. Sometimes they even mimic their children’s cute mistakes. Furthermore, residential homes are not highly controlled laboratories—the stimulus-response-consequence contingencies are far from perfect.

The Nativist Perspective

The nativist perspective, turning to innate mechanisms for language development, has the following underlying assumptions: language is a human-species-specific capacity; language is “unlearnable” because it is impossible for a naïve and immature child to figure out such a complex linguistic system from an imperfect, not very consistent, highly opaque, and frequently ambiguous language environment; and there is a common structural core in all human languages. In 1965, linguist Noam Chomsky posited an innate language-acquisition device (LAD), with the universal grammar residing in it, to explain children’s rapid acquisition of any language and even multiple languages. LAD is assumed to be a part of the brain, specialized for processing language. Universal grammar is the innate knowledge of the grammatical system of principles and rules expressing the essence of all human languages. Its transformational generative grammar consists of rules to convert the deep structure (grammatical classes and their relationships) to surface structure (the actual sentences said) in the case of production, or vice versa in the case of comprehension. Equipped with this biological endowment, children need only minimal language exposure to trigger the LAD, and their innate knowledge of the universal grammar will enable them to extract the rules for the specific language(s) to which they are exposed.

Evidence for the nativist perspective can be discussed at two levels: the linguistic level (language rules and structure) and the biological level. At the linguistic level, people are sensitive to grammatical rules and linguistic structural elements. For example, sentences in the active voice are processed more quickly than sentences in the passive voice, because the former type is closer to the deep structure and needs fewer transformation steps than the latter type. Click insertion studies (which insert a click at different places in a sentence) and interrupted tape studies (which interrupt a tape with recorded messages at different points) have shown a consistent bias for people to recall the click or interruption position as being at linguistic constituent boundaries, such as the end of a clause. After a sentence has been processed, what remains in memory is the meaning or the gist of the sentence, not its word-for-word surface structure, suggesting the transformation from the surface structure to the deep structure.

Around the world, the structure of creolized languages (invented languages), including the sign languages invented by deaf children who have not been exposed to any language, is similar and resembles early child language. Young children’s early language data have also rendered support. In phonology, habituation studies show that newborns can distinguish between phonemes such as /p/ and /b/. Most amazingly, they perceive variations of a sound as the same if they come from the same phoneme, but different if they cross the boundary into a different phoneme (categorical speech perception). In semantics, babies seem to know that object labels refer to whole objects and that a new word must mean the name of a new object. If the new word is related to an old object whose name the child already knows, the word must mean either a part or a property of that object (the mutual exclusivity hypothesis). In the domain of grammar, Dan Isaac Slobin’s 1985 cross-cultural data have shown that young children pay particular attention to the ends of words and use subject-object word order, probably as a function of their innate operating principles. By semantic bootstrapping, young children know that object names are nouns and that action words are verbs. By syntactic bootstrapping, they understand a word’s grammatical class membership according to its position in a sentence. Even young children’s mistaken over-regularization of grammatical rules to exceptions demonstrates their success in rule extraction, since such mistaken behavior is not modeled by adults.

The Neural Storehouse

At the biological level, human babies seem to be prepared for language: They prefer the human voice to other sounds and the human face to other figures. Some aspects of the language developmental sequence appear to be universal—even deaf children, despite their lack of language input, start to coo and babble at about the same ages as hearing children and later develop sign combinations that are very similar to telegraphic speech. Children’s language environment is indeed quite chaotic, yet it takes them only four to five years to speak their mother tongue like an adult without systematic, overt teaching. Furthermore, a critical or sensitive period seems to exist for language acquisition. Young children are able to pick up any language or a second language effortlessly, with no accent or grammatical mistakes. After puberty, people generally have to exert great efforts to learn another language, and their pronunciation as well as grammar typically suffers. Reinforced language teaching in postcritical years was not successful in the cases of “Victor” (a boy who had been deserted in the wild) and “Genie” (a girl who had been confined in a basement). Kako’s 1999 study—a careful analysis of the linguistic behavior of a parrot, two dolphins, and a bonobo—led him to conclude that no nonhuman animals, including the language-trained ones, show all the properties of human language in their communication, although he respectfully acknowledges all the achievements in animal language training. Language is unique to human beings.

Although the neural storehouse for the universal grammar has not been pinpointed yet, cognitive neuroscience has delivered some supportive evidence. Infants’ brains respond asymmetrically to language sounds versus nonlanguage sounds. Event-related potentials (ERPs) have indicated localized brain regions for different word categories in native English speakers. Research suggests possible specific brain structures that had registered a detailed index for nouns. Brain studies have confirmed the left hemisphere’s language specialization relative to the right hemisphere, even among very young infants. Broca’s area and Wernicke’s area are housed in the left hemisphere. Damage to Broca’s area results in Broca’s aphasia, with a consequence of producing grammatically defective, halting, telegram-like speech. When Wernicke’s area is damaged, speech fluency and grammatical structure are spared but semantics is impaired. This linguistic lateralization pattern and the linguistic consequences of brain injuries are also true of normal and aphasic American Sign Language users.

However, the nativist perspective is not immune to criticism. The universal grammar cannot adequately explain the grammatical diversity in all human languages. The growth spurts in brain development do not correspond to language development in a synchronized manner. The importance of social interaction, contextual factors, and formal education for knowledge and pragmatic usage of complex rules, subtle expressions, speech acts, and styles has been neglected in nativist theories.

Dissatisfied with this nature-nurture dichotomy, interactionist theories try to bring the two together. They recognize the reciprocal influences, facilitating or constraining, dependent or modifying, among multiple factors from the biological, cognitive, linguistic, and social domains. For instance, the typical prenatal and postnatal mother-tongue environment will eventually wean the infants’ initial ability to differentiate the speech sounds of any language and, at the same time, sharpen their sensitivity to their native language. Deaf children’s babbling does not develop into words as does that of hearing children. Babies deprived of the opportunity of social interaction, as seen in the cases of “Victor” and “Genie,” will not automatically develop a proper language. It is in the dynamic child-environment system that a child acquires language.

Language and Cognition

Cognitive Development and Language Acquisition

Cognitive theorists generally believe that language is contingent on cognitive development. The referential power in the arbitrary symbols assumes the cognitive prerequisite of understanding the concepts they signify. As a cognitive interactionist, Jean Piaget believed that action-based interaction with the world gave rise to the formation of object concepts, separation of self from the external world, and mental representation of reality by mental images, signs, and symbols (language). Language reflects the degree of cognitive maturity. For example, young children’s immature egocentric thought (unable to understand others’ perspectives) is revealed in their egocentric speech (talking to self)—children seem to show no realization of the need to connect with others’ comments or to ascertain whether one is being understood. Older children’s cognitive achievements of logical thinking and perspective-taking lead to the disappearance of egocentric speech and their use of socialized speech for genuine social interaction. Although language as a verbal tool facilitates children’s interaction with the world, it is the interaction that contributes to cognitive development. Piaget gave credit to language only in the later development of abstract reasoning by adolescents.

In L. S. Vygotsky’s social-functional interactionist view, language and cognition develop independently at first, as a result of their different origins in the course of evolution. Infants use practical/instrumental intelligence (intelligence without speech), such as smiling, gazing, grasping, or reaching, to act on or respond to the social world. Meanwhile, the infants’ cries and vocalizations, though they do not initially have true communicative intent (speech without thinking), function well in bringing about adults’ responses. Adults attribute meaning to infants’ vocalizations and thus include the babies in the active communicative system, fostering joint attention and intersubjectivity (understanding each other’s intention). Such social interactions help the infants eventually complete the transition from nonintentional to intentional behavior and to discover the referential power of symbols, thus moving on to verbal thinking and later to meaningful speech. Externalized speech (egocentric speech) is a means for the child to monitor and guide his or her own thoughts and problem-solving actions. This externalized functional “conversation with oneself” (egocentric speech) does not disappear but is internalized over time and becomes inner speech, a tool for private thinking. Thus, in Vygotsky’s theory, language first develops independently of cognition, then intersects with cognition, and contributes significantly to cognitive development thereafter. Language development proceeds from a global, social functional use (externalized speech) to a mature, internalized mastery (inner speech), opposite to what Piaget suggested.

Linguistic Relativity

Linguistic relativity refers to the notion that the symbolic structure and use of a language will shape its users’ way of thinking. The Sapir-Whorf hypothesis, also known as linguistic determinism, is a strong version. According to anthropologist John Lucy, writing in 1997, all the variations of linguistic relativity, weak or strong, share the assumption that “certain properties of a given language have consequences for patterns of thought about reality. . . . Language embodies an interpretation of reality and language can influence thought about that reality.” Many researchers have tested these claims. Lera Boroditsky, for example, in a 2001 study, examined the relationship between spatial terms used to talk about time and the way Mandarin Chinese speakers (using vertical spatial metaphors) and English speakers (using horizontal spatial metaphors) think about time. The findings suggested that abstract conceptions, such as time, might indeed be subject to the influence from specific languages. On the other hand, the influence between language and thought might be more likely bidirectional than unidirectional. Many examples from the civil rights movement or the feminist movement, such as the thought of equality and bias-free linguistic expressions, can be cited to illustrate the reciprocal relationships between the two.

Language Faculty as a Module

There have been debates over whether language is a separate faculty or a part of general cognition. Traditional learning theories are firm in the belief that language is a learned verbal behavior shaped by the environment. In other words, language is not unique in its own right. By contrast, nativist theorists insist on language being an independent, innate faculty. Chomsky even advocates that, being one of the clearest and most important separate modules in the individual brain, language should be viewed internally from the individual and therefore be called internal language or “I-language,” distinct from “E-language” or the external and social use of language. Nativists also insist on language being unique to humans, because even higher-order apes, though they have intelligence (such as tool using, problem solving, insights) and live a social life, do not possess a true language.

The view of language as an independent faculty has received support from works in cognitive neuroscience, speech-processing studies, data associated with aphasia (language impairment due to brain damage), and unique case studies. Specific word and grammatical categories seem to be registered in localized regions of the brain. Some empirical studies have suggested that lexical access and word-meaning activation appear to be autonomic (modular). As noted, Broca’s aphasia and Wernicke’s aphasia display different language deficit symptoms. In 1991, Jeni Yamada reported the case of Laura, a person with an IQ score of just 41 when she was in her twenties. Her level of cognitive problem-solving skill was comparable to that of a preschooler, yet she was able to produce a variety of grammatically sophisticated sentences, such as “He was saying that I lost my battery-powered watch that I loved; I just loved that watch.” Interestingly, Laura’s normal development in phonology, vocabulary, and grammar did not protect her from impairment in pragmatics. In responding to the question, “How do you earn your money?,” Laura answered, “Well, we were taking a walk, my mom, and there was this giant, like, my mother threw a stick.” It seems that some components of language, such as vocabulary and grammar, may function in a somewhat autonomic manner, whereas other parts, such as pragmatics, require some general cognitive capabilities and social learning experiences.

Cognitive psychologists hold that language is not a separate module but a facet of general cognition. They caution people against hasty acceptance of brain localization as evidence for a language faculty. Arshavir Blackwell and Elizabeth Bates (1995) have suggested an alternative explanation for the agrammaticality in Broca’s aphasia: grammatical deficits might be the result of a global cognitive resource diminution, rather than just the damaged Broca’s area. In 1994, Michael Maratsos and Laura Matheny criticized the inadequate explanatory power of the language-as-a-faculty theory pertaining to the following phenomena: comprehension difficulties in Broca’s aphasia in addition to grammatical impairment; semantically related word substitutions in Wernicke’s aphasia; the brain’s plasticity or elasticity (the flexibility of other parts of the brain adapting to pick up some of the functions of the damaged parts); and the practical inseparability of phonology, semantics, syntax, and pragmatics from one another.

Some information-processing models, such as connectionist models, have provided another way to discuss language, not in the traditional terms of symbols, rules, or cognitive capacity, but in terms of the strengths of the connections in the neural network. Using computer modeling, J. L. McClelland explains that knowledge is stored in the weights of the parameter connections, which connect the hidden layers of units to the input units that process task-related information and the output units that generate responses (performance). Just like neurons at work, parallel-distributed processing, or many simultaneous operations by the computer processor, will result in self-regulated strength adjustments of the connections. Over extensive trials, the “learner” will go through an initial error period (the self-adjusting, learning period), but the incremental, continual change in the connection weights will give rise to stage-like progressions. Eventually, the machine gives rule-like performance, even if the initial input was random, without the rules having ever been programmed into the system. These artificial neural networks have successfully demonstrated developmental changes or stages in language acquisition (similar to children’s), such as learning the past tense of English verbs.

As a product of the neural network’s experience-driven adjustment of its connection weights, language does not need cognitive prerequisites or a specific language faculty in the architecture (the brain). Although emphasizing learning, these models are not to prove the tabula rasa (blank slate) assumption of traditional behaviorism, either, because even small variations in the initial artificial brain structure can make qualitative differences in language acquisition. The interaction between the neural structure and environment (input cues and feedback patterns) is further elaborated in dynamic systems models. For example, Paul van Geert’s dynamic system, proposed in 1991, is an ecosystem with heuristic principles modeled after the biological system in general and the evolutionary system in particular. The system space consists of multiple growers or “species” (such as vocabulary and grammatical rules) in interrelated connections. Developmental outcome depends on the changes of the components in their mutual dependency as well as competition for the limited internal and external resources available to them.

Conclusion

As Thomas M. Holtgraves said in 2002, “It is hard to think of a topic that has been of interest to more academic disciplines than language.” Language can be analyzed at its pure, abstract, and symbolic structural level, but it should also be studied at biological, psychological, and social levels in interconnected dynamic systems. Continued endeavors in interdisciplinary investigations using multiple approaches will surely lead to further understanding of language.

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