Language Acquisition | Psychology for UPSC Optional (Notes) PDF Download

Introduction

Language, as understood by cognitive psychologists, serves as a means of transmitting thoughts through sounds (speech and music) or symbols (written words and gestures). It is a captivating process in which one mind influences another. This process leads to permanent changes in certain cell assemblies within the brain, generating new thoughts and transforming individuals.
While the scientific study of language and thought gained popularity in the 1950s through cognitive psychology, philosophers and metaphysicians have explored these subjects since ancient Greek times. René Descartes, for instance, famously stated, "I think, therefore I am."
Today, the advancement of tools for examining brain activity has enabled cognitive psychology to flourish as a scientific discipline. Cognitive psychologists delve into questions regarding the impact of language on thought, the potential for creating artificial intelligence capable of thinking, and the motivations behind human artistic expression.

Language and Cognition

Cognitive psychologists recognize the significance of studying human language due to the following reasons:

• Unique Abstraction: Human language development involves a distinct form of abstraction that is fundamental to cognition. Although other species (bees, birds, dolphins, dogs, etc.) possess elaborate communication systems, and apes exhibit a form of abstract language usage, humans exhibit a significantly higher degree of abstraction.
• Information Processing: Language processing plays a crucial role in information storage and processing.
  
• Thinking and Problem Solving: Human thinking and problem-solving processes can be conceptualized as involving language. Many cognitive processes occur internally, independent of external stimuli. Verbal symbolization of puzzles, for instance, provides a way to contemplate potential solutions.
  
• Communication: Language serves as the primary means of human communication, facilitating the exchange of information.
  
• Influence on Perception: Language has a profound influence on perception, a fundamental aspect of cognition. Some argue that the language we use to describe the world affects our perception of it. Simultaneously, language development is largely based on our perception of language, creating an interdependent relationship between perception and language. Language functions, such as word processing, speech, and semantics, engage specific cerebral areas, establishing a meaningful link between neuroanatomical structures and language. Additionally, the study of brain pathologies frequently reveals significant changes in language functions, such as aphasia.
  

Linguistics

Linguistics involves the formal description of language structure, encompassing speech sounds, meanings, and grammar. Linguists typically approach language from a competency-based perspective, focusing on the ideal potential of language users. In contrast, psychologists view language in terms of performance, examining how humans use language in practice. The interdisciplinary field that incorporates both approaches to language study is known as psycholinguistics.

The Structure of Language

Language is a system comprising symbols and rules used for meaningful communication. For a system to be considered a language, it must fulfill specific criteria:

• Symbolic Nature: A language employs symbols, which can be sounds, gestures, or written characters, representing objects, actions, events, and ideas. Symbols allow reference to entities and events that exist elsewhere or occurred at different times.
• Meaningfulness: Language possesses meaning, enabling comprehension among users.
  
• Generativity: A language allows the combination of symbols to generate an infinite number of messages.
  
• Rule-Governed: Languages have rules that dictate how symbols can be arranged, facilitating understanding even when encountering novel messages.
  

The Building Blocks of Language

Language is structured hierarchically, progressing from phonemes to morphemes, phrases, and sentences, conveying meaning. Key components include:

• Phonemes: These are the smallest discernible units in a language. In English, certain consonants like "t," "p," and "m" correspond to single phonemes, while others like "c" and "g" can represent multiple phonemes. Vowels typically correspond to more phonemes, as in the case of "o" in "bone" or "woman." Some phonemes combine consonants, such as "ch," "sh," and "th."
• Morphemes: Morphemes are the smallest meaningful units in a language. In English, a few single letters, like "I" and "a," function as morphemes. Morphemes are usually complete words or meaningful components of words, including prefixes, suffixes, and word stems. For example, the word "disliked" consists of three morphemes: "dis," "lik," and "ed."
  
• Syntax: Syntax comprises a set of rules governing the meaningful arrangement of words to form phrases and sentences. For instance, the rule that an article like "the" must precede a noun, as in "Read the book," rather than following it as in "Read book the."
  

Language Acquisition

Language acquisition is a central topic within cognitive science, eliciting significant controversy and interest. Acquiring language is a uniquely human trait, and it is closely intertwined with understanding other people's thoughts. Children effortlessly learn their first language within a few years, without formal instruction.
As language is intrinsic to human nature, extensive attention has been devoted to studying children's language acquisition. Current understanding acknowledges that language acquisition involves a natural capacity influenced by the environment.
Researchers employ the concept of innately guided learning to explore which abilities are innate and how the child's environment shapes these abilities. Past debates focused on the nature versus nurture dichotomy, but the contemporary approach recognizes the interplay between innate capacities and environmental influences.

Stages of Language Acquisition

• Around the world, individuals appear to acquire their primary language in a similar sequence and manner. Research on speech perception indicates a consistent pattern of development, progressing from general to specific abilities. Initially, infants possess the ability to discern all possible phonetic differences. 
• However, with time, they lose the ability to distinguish nonnative contrasts and instead focus on the phonetic distinctions present in their native language environment. Infants display remarkable language-learning capabilities, even from an early age. During the first few years of life, humans progress through several stages of language production. 
• These stages include cooing, which primarily consists of vowel sounds and is indistinguishable across babies and languages. Infants exhibit superior sound discrimination skills compared to adults and can discern phonetic differences that adults may overlook. As infants enter the babbling stage, they produce both consonant and vowel sounds, which may sound similar across different language groups. Deaf infants cease vocalizing during this stage, while hearing infants primarily produce phonemes characteristic of their own language. 
• Subsequently, infants progress to one-word utterances, limited in their utilization of vowels and consonants. They employ these holophrases to convey intentions, desires, and demands, typically using nouns to describe familiar objects or express wants. By around 18 months, children typically acquire a vocabulary of 3 to 100 words, although their vocabulary may not encompass everything they wish to describe, leading to overextension errors. 
• Between 1.5 and 2.5 years of age, children begin combining single words to form two-word utterances, marking the emergence of rudimentary syntax referred to as telegraphic speech. Eventually, children develop a grasp of basic adult sentence structure, expand their vocabulary significantly, and acquire the foundations of adult syntax and language structure by the age of 4. 
• By age 5, most children can comprehend and produce complex sentence constructions, and by age 10, their language is fundamentally similar to that of adults. Although the rate of language development may vary among children, the stages they progress through generally remain consistent.

Language Acquisition and Cognitive Science

• The study of language acquisition presents an opportunity to explore concrete answers to questions within cognitive science. The scientific investigation of language acquisition emerged concurrently with the inception of cognitive science in the late 1950s. Noam Chomsky's review of Skinner's Verbal Behavior played a pivotal role at that time. 
• Previously, there was a consensus in Anglo-American natural science, social science, and philosophy that viewed the mind as comprising sensorimotor abilities and simple laws of learning governing gradual changes in behavior. 
• Consequently, language was considered a learned skill, incapable of existing as a module, and thinking was considered a form of verbal behavior observable externally. Chomsky's argument, based on language acquisition, challenged these beliefs by demonstrating that children acquire languages governed by subtle and abstract principles without explicit instruction or environmental clues. 
• This suggested the existence of an innate, species-specific module distinct from general intelligence for language acquisition. Much of the subsequent debate on language acquisition has aimed to test these revolutionary and still controversial ideas, with implications extending to other aspects of human cognition.

Language and Thought

• The relationship between language and cognition raises questions about whether language is merely an overlay on cognition, allowing communicable labels for thoughts, or if learning a language involves learning to think in that language. 
• Benjamin Whorf's hypothesis posits that the categories and relationships we use to understand the world are shaped by our particular language, implying that speakers of different languages conceptualize the world differently. 
• However, modern cognitive scientists widely regard this hypothesis as false. It is established that babies can engage in thought before they can speak, and cognitive psychology has demonstrated that thinking occurs not only in words but also in images and abstract logical propositions. Language acquisition, nevertheless, contributes uniquely to this matter. 
• It is challenging to explain how children learn a language without assuming the presence of a substantial amount of nonlinguistic cognitive machinery prior to language acquisition.

Theories of Language Acquisition

How do we account for the process of language acquisition in children, particularly their remarkable and early proficiency? Multiple mechanisms contribute to this phenomenon. As discussed in the following section, the brain undergoes post-birth changes that may influence the onset, speed, and eventual decline of language acquisition ability.
Additionally, the child's overall information processing skills, such as attention, memory, and the ability to process auditory input and produce speech, can also play a role. Given the complexity of language acquisition, a precise framework is necessary to comprehend its various aspects. In the past five decades, several theories have emerged to explain how children learn to understand and speak a language.
These theories, summarized in the table below, have contributed to our understanding of language acquisition by emphasizing different aspects of the process. It is crucial to note that these theories should not be viewed as conflicting replacements in a sequential manner. Although Behaviorism is now considered to provide a limited explanation, each theory has added to our overall understanding by focusing on different facets.

Behavioristic Theory

The behaviorist psychologists developed their theories through experiments on animals. By employing positive reinforcement, desirable behavior was rewarded, while undesirable behavior was either punished or ignored. B. F. Skinner, a behaviorist, proposed this theory to explain language acquisition in humans. According to Skinner, children imitate the language used by their parents or caregivers, and successful attempts are reinforced through praise or receiving what they desire. Language acquisition, according to Skinner, resembles the learning process of a rat navigating a maze.

Limitations of Behaviorism Theory

• While Skinner's explanation contains some truth, several objections can be raised. Language is based on structures and rules that cannot be deduced solely by imitating individual utterances. Children's mistakes reveal that they actively work out and apply rules rather than simply imitate. 
• Furthermore, the sequence of language acquisition stages seems largely unaffected by external factors such as parental treatment or the cultural environment. Children often struggle to repeat adult speech containing structures they haven't yet acquired, and explicit grammatical correction is rare. Instead, parents tend to prioritize politeness and truthfulness. 
• The existence of a critical period for language acquisition is supported by evidence, as children who haven't acquired language by a certain age never fully catch up. Extreme cases, such as Genie's, demonstrate the limitations of language acquisition beyond a certain age.

Innateness Theory

• In 1957, Noam Chomsky criticized the behaviorist theory and proposed an alternative perspective. Chomsky argued that children receive limited language input, yet they possess an innate capacity for language learning. 
• Language acquisition is linked to the cognitive structure of the human mind, and certain aspects of language structure are preordained. This innate faculty, known as the Language Acquisition Device (LAD), enables children to discover the grammar of their language. 
• Chomsky emphasized that while specific languages differ, they share common underlying principles, and the child's task is to uncover how their particular language expresses these principles. The process is unconscious, and Chomsky's theory remains a central point in the language acquisition debate.

Evidence Supporting Innateness Theory

• Several areas of language study provide support for the notion of an innate language faculty. Human anatomy, distinct brain areas like Broca's and Wernicke's areas, and stroke victims' language impairments offer evidence of a specialized language mechanism. 
• Attempts to teach chimpanzees to communicate using symbols or gestures have been inconclusive, indicating that apes lack grammatical competence. 
• The formation of creole languages, observed in situations where diverse language groups are forced to communicate using a limited lingua franca, showcases the LAD's role. Additionally, sign languages used by the deaf have been found to be complex and grammatically complete languages, with signing creoles even emerging in certain contexts.

Limitations of Chomsky’s Theory

• Chomsky's linguistic theory primarily focused on grammar and provided intricate explanations of grammatical rules. However, it had certain limitations. Firstly, Chomsky did not conduct studies on real children to validate his theory. 
• He disregarded the interaction between children and their caretakers, which plays a crucial role in language acquisition. Moreover, his theory did not consider the functions of language or the reasons why a child desires to communicate. 
• A study conducted by Bard and Sachs in 1977, examining a child named Jim, revealed that simply being exposed to language through television and radio was insufficient for language development. It was only when a speech therapist engaged with Jim that he made significant progress, highlighting the importance of interactive language experiences. Subsequent theories placed greater emphasis on how children develop language to fulfill their needs and interact with their environment and others.

Cognitive Theory

• Jean Piaget, a Swiss psychologist, proposed the cognitive theory, which contextualizes language acquisition within a child's cognitive development. According to Piaget, a child must comprehend a concept before acquiring the language structures to express it. Cognitive theory views language acquisition as part of a child's broader intellectual growth. 
• Piaget outlined four distinct stages that children universally progress through in a fixed order. These stages differ in the amount and quality of knowledge acquired at each stage. Piaget asserted that a child transitions from one stage to the next when they reach a suitable level of maturation and encounter relevant experiences. 
• Piaget's stages are sensorimotor, preoperational, concrete operational, and formal operational. In the sensorimotor stage (from birth to around two years), a child has limited abilities to represent the environment using symbols or language. Object permanence, the understanding that objects exist even when not visible, is absent during this stage. 
• The preoperational stage (from two to seven years) is marked by the development of language and the ability to mentally represent the world. However, thinking remains egocentric, and children struggle with conservation, understanding that changes in appearance do not alter quantity. The concrete operational stage (from seven to twelve years) is characterized by logical thinking, overcoming egocentrism, and the mastery of concepts like reversibility. 
• Children also develop a better understanding of time and space. The formal operational stage (from twelve into adulthood) introduces abstract, formal, and logical thinking. However, not all individuals fully achieve this stage. Piaget's theory has influenced educational curricula by emphasizing the role of cognitive readiness and experiential learning in cognitive performance.

Limitations of Cognitive Theories

• While cognitive theories explain the cognitive development underlying language acquisition, they do not address why language emerges initially. Apes undergo similar cognitive development in their early years as young children but do not naturally acquire language. 
• Bees, for example, develop cognitive abilities to perceive various shades of color but do not develop communication signals based on color. As children continue to develop, it becomes challenging to establish clear links between language and intellect. 
• Some studies have observed children with abnormal mental development who still acquire fluent speech, indicating that syntax, in particular, does not depend on general intellectual growth.

Input or Integrationist Theories

• Contrary to Chomsky's work, more recent theorists have emphasized the significance of language input from caregivers in children's language acquisition. These interactionists, including Jerome Bruner, propose that adults adapt their language behavior when communicating with children, known as child-directed speech (CDS), to support the language learning process. 
• This support, often referred to as scaffolding, assists children in acquiring language. Bruner introduced the term Language Acquisition Support System (LASS) as an alternative to Chomsky's Language Acquisition Device (LAD). The turn-taking structure of conversation, developed through games and non-verbal communication, precedes verbal utterances in children. 
• Language input theories suggest that children receive sentences in a contextual framework, along with a representation of their meaning inferred from the context and the child's existing knowledge of word meanings.

Limitations of Input Theories

• Input theories offer valuable insights challenging Chomsky's early stance, suggesting that frequent interaction accelerates language learning. 
• However, it is important to note that children across different cultures pass through the same stages of language acquisition. Additionally, there are cultures where adults do not employ specialized forms of speech when addressing children, implying that child-directed speech may be helpful but not essential. 
• It is crucial to understand that these various theories should not be seen as exclusive alternatives but rather as complementary explanations that provide partial understanding of the language acquisition process.

The Biology of Language Acquisition

Language acquisition in humans is facilitated by specific adaptations in the human mind and body that emerged through the process of human evolution. Children utilize these adaptations to acquire their native language. 

• One notable adaptation is the shape of the human vocal tract, which appears to have evolved to meet the demands of speech. Humans have a low larynx and a vocal tract with a sharp right angle bend, allowing for the production of a wide range of vowel sounds through independently modifiable resonant cavities, namely the mouth and the pharynx or throat.
• While it may be tempting to find precursors of language in our closest relatives, the chimpanzees, research has shown that artificial chimp signaling systems, although sharing some similarities to human language in terms of communication and signal combinations, are not homologous. 
• Chimpanzees require extensive and structured teaching sequences devised by humans to acquire limited language abilities, mainly focused on simple requests or actions. In contrast, human children spontaneously acquire thousands of words, combine them in structured sequences, adhere to word order rules, and use sentences for various purposes.
• This lack of homology between human language and chimpanzee communication does not challenge the gradualist Darwinian account of language evolution. Humans and chimpanzees share a common ancestor, but language likely evolved in the human lineage due to the development of technology, knowledge of the environment, and extensive reciprocal cooperation. These factors allowed for the sharing and exchange of valuable knowledge among individuals.

Maturational Changes in Brain

• The maturation of language circuits during early childhood plays a crucial role in language acquisition. As the brain develops, various changes contribute to the acquisition process. Before birth, all neurons are formed and migrate to their appropriate brain locations. 
• However, head size, brain weight, and the thickness of the cerebral cortex, where mental computations occur, continue to increase rapidly during the first year after birth. Long-distance connections in the brain are not fully established until around nine months, and their myelin insulation, which enhances their speed, continues to develop throughout childhood.
• Synapses, the junctions between neurons, continue to develop and reach their peak in number between nine months and two years, at which point a child has significantly more synapses than an adult. Metabolic activity in the brain reaches adult levels around nine to ten months and then surpasses it, peaking at approximately four years of age.
• From the age of two onward, synapses begin to wither, and this process continues throughout childhood and into adolescence, when the brain's metabolic rate returns to adult levels.
  
• It is plausible that linguistic milestones, such as babbling, first words, and grammar, require specific levels of brain size, long-distance connections, or additional synapses, particularly in the language centers of the brain. Similarly, these maturational changes may account for the decline in language learning ability as individuals age. 
• The brain's language learning circuitry is more plastic in childhood, as evidenced by children's ability to learn or recover language even when the left hemisphere of the brain is damaged or surgically removed. In contrast, comparable damage in adults typically leads to permanent language impairment.
  
• Research indicates that age plays a crucial role in language acquisition. Children can typically acquire language successfully until around the age of six, with guaranteed language acquisition up to the age of four. However, language acquisition becomes progressively compromised from that point until shortly after puberty and becomes rare thereafter. 
• Maturational changes in the brain, such as the decline in metabolic rate and the number of neurons during the early school-age years, as well as the stabilization of synapse numbers and metabolic rate around puberty, may contribute to this phenomenon. Thus, there may be a neurologically determined "critical period" for successful language acquisition, similar to critical periods observed in visual development in mammals and the acquisition of songs in certain bird species.
  

Dissociations Between Language and General Intelligence

• Human brains have evolved specific circuitry, primarily in the left hemisphere surrounding the sylvian fissure, that appears to be dedicated to language processing. However, the exact mechanisms by which this internal wiring gives rise to language rules remain unknown. 
• Strokes often result in severe language impairments in adults while leaving other aspects of intelligence, such as those measured in nonverbal parts of IQ tests, relatively unaffected. Conversely, there are syndromes in which individuals exhibit intact language abilities despite significant cognitive impairments.
• One example is Williams Syndrome, an inherited condition characterized by physical abnormalities, significant cognitive retardation (with an average IQ of approximately 50), difficulties in performing everyday tasks, social warmth and gregariousness, and surprisingly, fluent and articulate language skills.

Neural Networks

Certain cognitive neuroscientists have developed neural networks or computer models that can acquire certain aspects of language without being preprogrammed with specific rules. These neural networks are exposed to numerous examples of a language, allowing them to learn the language's statistical structure and accurately generate past tense verb forms. It is speculated that children may acquire language in a similar manner, through exposure to multiple examples.