Age-related Factors in Language Development (Notes)

Introduction: Age and Language Development Context

• Narrative comparison: Lina (child) vs. Carlos (adult) learning English in the US after moving from Colombia.
  • Lina: Spanish at home, learns English at preschool; rapid acquisition, becomes fluent, code-switching between school English and home Spanish.
  • Carlos: adult; takes English classes but slower, more conscious vocabulary/grammar learning; subjects the question of why children learn more easily.
• Purpose of the chapter: explore how age influences language development across the lifespan.
  • Key aims: examine critical period hypothesis (CPH), ultimate attainment, child instructed SLA, and bilingual/multilingual development.
  • Investigate cognitive, social, and environmental factors shaping language learning at different life stages.
• Chapter structure: overview of age-related factors, followed by detailed discussions on critical age-related hypotheses and SLA research findings.

Key Concepts in Age-Related Language Development

• Critical Period Hypothesis (CPH): there is a biologically determined window during which language acquisition occurs most naturally and efficiently; after this window, learning to native-like proficiency becomes more difficult.
• Ultimate Attainment: the highest level of proficiency achievable in an additional language after extensive exposure/use; not necessarily native-like.
• Age of Acquisition (AoA): age at which a learner first acquires a particular linguistic feature or word; often linked to eventual proficiency patterns.
• Age of Onset (AO): age when regular, sustained exposure to the L2 begins (e.g., immersion in L2 environment).
• Length of Residence (LoR): duration of time spent in an L2 environment; interacts with input quality/quantity to influence attainment.
• Quality vs. Quantity of Input: not just how much exposure, but the diversity and usefulness of that exposure; higher-quality input can boost outcomes even with less time.
• Sociopsychological Variables: motivation, identity, attitudes toward the L2 culture, and social integration influence attainment.
• Instructed vs. Naturalistic SLA: differences in context (classroom instruction vs. immersion) with distinct outcomes.
• Bilingual/Multilingual Development: how learning/manage multiple languages from early life compares to acquiring languages later; includes concepts like multicompetence and dynamic systems theory.
• Translanguaging and Code-Switching: real-world language practices among bilinguals; implications for learning and classroom practices.
• The role of input, interaction, and social context: joint attention, intention reading, and other social-cognitive factors as drivers of language development.

First Language Development

• Pre-Linguistic Stage (0–12 months):
  • Vocalization and auditory perception; cooing ≈ 2 months; babbling ≈ 6–8 months.
  • Purpose: experimentation with phonemes/intonation; babies begin differentiating sounds of their first language(s).
  • Key features: cooing, babbling, phonemic awareness development.
• One-Word Stage (12–18 months): holophrastic stage; single words express whole ideas; often with gestures.
  • Example: a child saying "milk" to mean “I want milk.”
• Two-Word Stage (18–24 months): two-word combinations forming basic sentences (subject-verb or verb-object).
  • Examples: "want cookie"; "mommy go".
  • Indicates emerging rudimentary syntax.
• Telegraphic Speech Stage (24–30 months): usually 3+ words; omit nonessential words (articles, auxiliary verbs) but retain core syntax.
  • Demonstrates growing understanding of sentence structure.
• Multiword Stage (30+ months): speech becomes more complex; use function words (prepositions, conjunctions); form complex sentences; ask questions; use negatives; embedded clauses.
• Variability and timing:
  • Stages are generally consistent across languages, but exact timing varies by language and individual.
  • Language development is continuous and overlapping; not strictly sequential or universal.
  • Individual differences in timing/pace are common; input quantity/quality and social interaction are crucial.
• Neural and cognitive underpinnings:
  • Neural plasticity plays a crucial role, especially in early stages.
  • Language development intertwines with gesture and broader cognitive/motor development.
• Theories of First Language Acquisition (overview):
  • Behaviorist Theory (Skinner, 1957): language learned via habit formation and reinforcement; operant conditioning; input/reinforcement shape utterances.
  • Nativist Approach (Lenneberg, 1967; Chomsky, 1965): language acquisition is innate; Language Acquisition Device (LAD); universals/UG; innate predispositions reduce reliance on input alone.
  • Connectionist & Emergentist Approaches: language learning via neural networks and domain-general cognitive mechanisms; input-driven, distributed representations; competition model (MacWhinney, 1987, 2004) emphasizes cue competition and mapping forms to functions; Plunkett & Juola (1999) illustrate U-shaped learning in past tense acquisition; emergentist views stress processing efficiency and input-driven development (O’Grady, 2005).
  • Functional & Usage-Based Perspectives (Tomasello, 2003): language learned from real communicative experience; three core factors: input frequency, pattern extraction, social interaction; early language is item-based and gradually abstracts as patterns are detected; joint attention and intention reading are pivotal for social-cognitive grounding of language.
• Joint attention and intention reading (examples):
  • Joint attention: shared focus on an object/event; caregiver directs attention (e.g., pointing to a car while saying “Look, car!”); supports word-object mapping.
  • Intention reading: understanding others’ goals behind utterances/actions (e.g., requesting the spoon while looking at the spoon); essential for interpreting indirect speech acts and communicative intent.
  • Both processes underpin early vocabulary development and pragmatic aspects of language use; crucial for social-interaction-based learning.

The Critical Period Hypothesis (CPH)

• Core claim: there exists a biologically determined window during which language acquisition is most efficient; outside this window, native-like attainment becomes harder.
• Origin and scope:
  • Originally proposed by Lenneberg (1967) for first language; extended to second language acquisition with a proposed sensitive/critical period for L2 too.
• Supporting evidence and observations:
  • Feral children (e.g., Victor, Genie) show severe language difficulties when language exposure is severely delayed.
  • Brain lateralization and reduced neural plasticity after puberty are linked to decreased language-learning efficiency.
  • Johnson & Newport (1989): earlier exposure to L2 correlates with higher likelihood of native-like proficiency.
  • Kuhl (2004): infants are universal listeners; early phonetic learning peaks in the first 6–12 months; neural commitment leads to native-language specialization.
  • Neuroimaging findings show young learners often display quicker, more native-like neural processing for L2 than late learners.
• Challenges and critiques:
  • Large-scale and replication-oriented criticisms; some studies show adults can reach high levels of proficiency in vocabulary, syntax, and discourse even when starting after the presumed period.
  • Hartshorne et al. (2018): large sample suggesting age effects extend into late adolescence/early adulthood for certain aspects (e.g., grammar up to around 17.4 years for grammar; vocabulary may extend even later).
  • Vanhove (2013): methodological concerns in earlier CPH studies; the age-attainment relationship may be more gradual and context-dependent than a strict cut-off.
  • Some researchers propose a sensitive period rather than a strict critical period, with multiple sensitive periods for different aspects of language (Muñoz, 2008).
  • Pfenninger & Singleton (2019): contextual factors like learning environment, parental support, and bilingualism can modulate age effects, sometimes overshadowing age alone.
• Key takeaways:
  • While younger learners often show advantages in pronunciation and certain morphosyntactic aspects, age is not the sole determinant of success.
  • The current view favors a nuanced, multi-factor perspective: input, context, motivation, aptitude, and learning strategies interact with age.
  • Emphasis on sensitivity rather than a hard cutoff; benefits of early exposure exist, but learning at older ages remains feasible with appropriate conditions.
• Additional phonetic/phonological specifics:
  • Kuhl (2004) emphasizes that early phonetic learning is peak-oriented during the first 6–12 months; later, neural commitment narrows perceptual categories to the native language(s).
  • Early phonetic sensitivity does not guarantee native-like pronunciation in all aspects; other components (syntax, lexicon) may be more amenable to late attainment.

Ultimate Attainment in Second Language Acquisition

• Definition and scope:
  • Ultimate attainment = highest level of proficiency a learner can reach after extended exposure/use of the L2; not necessarily native-like.
  • Not solely determined by AoA/AO; influenced by multiple interacting variables.
• Key influencing factors:
  • Age of Acquisition (AoA) and Age of Onset (AO): negative correlation between AO and ultimate attainment (earlier onset generally linked to higher attainment), but exceptions exist.
  • Length of Residence (LoR): longer immersion typically aids proficiency, but quality and context of interaction matter more than time alone.
  • Quality and Quantity of Input: rich, varied, meaningful exposure boosts attainment; heavy reliance on limited input (especially in instructed settings) may cap attainment.
  • Sociopsychological Variables: motivation, identity, and social integration with the L2 community strongly influence outcomes.
  • Educational setting: naturalistic vs. instructed contexts; explicit instruction can improve accuracy and enable targeted learning, especially in early stages.
• Native-like attainment vs functional proficiency:
  • Some studies report late learners achieving native-like pronunciation and grammar (e.g., Moyer 2004; Bongaerts et al. 2000), especially with high motivation and extensive exposure.
  • Other studies argue that native-like attainment as a universal benchmark is unrealistic, particularly in instructed or multilingual contexts; functional proficiency may be more meaningful for communication.
  • Neuroimaging studies show highly proficient late L2 learners can exhibit native-like brain activation patterns, suggesting brain adaptation with sufficient input and practice.
• Critical discussion of measurement benchmarks:
  • Native-like attainment as a standard is contested; some researchers advocate for functional/pragmatic proficiency as a more ecologically valid measure in diverse settings.
  • Multilingual contexts may produce repertoires qualitatively different from monolingual native speakers, yet highly effective for communication (Muñoz, 2008; Muñoz & Singleton, 2011).
• Components of AoA/AO effects and related concepts:
  • AoA vs AO: AoA is the age at which a learner acquires a specific linguistic feature; AO is the age when systematic exposure begins.
  • Negative correlation between AO and ultimate attainment suggests earlier immersion supports better outcomes, but late learners can still achieve high proficiency in various domains (grammar, vocabulary, discourse).
  • Length of residence and input quality interact with AoA/AO to shape outcomes.
• Real-world implications:
  • Instruction should consider multiple factors (input quality, social integration, motivation) rather than focusing solely on age.
  • Education should aim for high-quality, meaningful input and opportunities for authentic language use to maximize ultimate attainment across ages.
• Native-like attainment in bilingual/multilingual contexts:
  • Mixed results: some late learners reach near-native or native-like levels in certain domains (pronunciation, grammar) while others do not.
  • Brain imaging indicates possibility of adapting neural processing with sufficient exposure, but benchmarks should be context-sensitive.

Child Instructed SLA (ISLA)

• Distinction between naturalistic SLA and instructed SLA:
  • Naturalistic SLA: language acquisition through immersion and interaction with native speakers.
  • ISLA: language learning through formal instruction or immersion programs with structured pedagogy and feedback.
• Effectiveness of ISLA for children:
  • Instructed settings can accelerate language development, especially when pedagogy is developmentally appropriate.
  • Explicit instruction in grammatical structures, corrective feedback, and task-based learning can enhance accuracy and uptake.
  • Interactive activities (storytelling, songs, games) engage children and support learning; task-based learning (e.g., completing meaningful tasks) shows promise.
• Pedagogical approaches and strategies:
  • Form-Focused Instruction (FFI): directs learners’ attention to specific linguistic forms within meaningful contexts; supports accuracy (Lyster, 2015).
  • Corrective feedback and recasts: recasts (reformulations) and explicit corrections help learners notice and correct errors (Oliver & Grote, 2010).
• Strengths of ISLA by age group:
  • Younger children: high cognitive plasticity; strong imitation abilities for pronunciation; positive attitudes toward language learning; less inhibition; effective implicit learning in rich input settings.
  • Older children/adolescents: faster initial learning rates; better metalinguistic awareness; stronger literacy-related skills; more effective use of explicit learning strategies; better test-taking skills; ability to leverage prior knowledge and experiences.
• Implications for adult learners (continuity from ISLA findings):
  • Adults can still benefit from ISLA-like principles, including explicit instruction, dialogic interaction, feedback, and targeted practice.
  • Emphasize cognitive strategies and prior knowledge to support learning outcomes.
• Strengths and limitations summary:
  • Younger learners: advantages in pronunciation, social motivation, implicit learning; more responsive to naturalistic immersion.
  • Older learners: advantages in cognitive strategies, metalinguistic awareness, and formal learning contexts; can achieve strong proficiency with high-quality input and deliberate practice.

Bilingual and Multilingual Language Development

• Types of bilingualism:
  • Simultaneous bilinguals: two or more languages acquired from birth or very early infancy; typically achieve high proficiency in both languages with similar milestones.
  • Sequential bilinguals: second language introduced after establishing the first language (often after age ~3); may show initial dominance of L1 and slower L2 development.
• Cognitive advantages of bilingualism:
  • Bilinguals often outperform monolinguals on executive function tasks (flexibility, cognitive control) and metalinguistic awareness.
  • Simultaneous bilinguals tend to acquire these benefits earlier; sequential bilinguals show gains with continued exposure and use (Adesope et al., 2010; Bialystok, 2011).
• Linguistic outcomes:
  • Simultaneous bilinguals: higher likelihood of native-like pronunciation and grammatical accuracy in both languages.
  • Sequential bilinguals: may retain an accent in L2 or show initial L1 dominance; with rich input, can achieve high L2 proficiency over time (Unsworth, 2016).
• Quantity vs. quality of input in bilingual development:
  • Both exposure quantity and input quality matter; diverse vocabulary, complex syntax, and meaningful interactions promote robust development (Fibla et al., 2022; Unsworth, 2016).
• Multicompetence and Dynamic Systems Theory (DST):
  • Multicompetence (Cook, 1991; Cook & Li, 2016): view that bilinguals’ language knowledge is an integrated system, not simply two monolinguals inside one mind; languages influence one another.
  • DST (de Bot, 2007; Herdina & Jessner, 2002): language development is a dynamic, nonlinear system influenced by input, use, context, and individual differences; change is continual.
  • Both frameworks challenge the idea of a rigid critical period by emphasizing ongoing, context-sensitive development across life.
• Cross-linguistic influence and social factors:
  • Crosslinguistic influence describes how knowledge of one language affects use in another.
  • Individual differences in bilingual development arise from input context, motivation, and sociocultural factors.
• Code-switching and Translanguaging:
  • Code-switching: alternating between languages within a conversation or utterance; reflects flexible navigation of linguistic resources and can have cognitive benefits (Poplack, 2004).
  • Translanguaging: using the whole linguistic repertoire to make meaning; blending elements from multiple languages to support learning and communication (García & Wei, 2014; Creese & Blackledge, 2015).
  • Translanguaging in classrooms can enhance learning and identity affirmation, though implementation requires teacher training and systemic support to move beyond monolingual norms (García & Wei, 2014).
• Practical implications for education:
  • Recognize and value multilingual repertoires; promote translanguaging as a resource for learning across content areas.
  • Provide rich, varied input across languages; create opportunities for meaningful communication and cross-language transfer.
• Summary points on bilingual/multilingual development:
  • Bilingualism offers cognitive and linguistic advantages when input quality and opportunities for use are strong.
  • Multicompetence and DST explain why bilinguals develop unique, dynamic language systems rather than simply two separate languages.
  • Classroom practices should leverage translanguaging, code-switching strategically, and avoid rigid monolingual norms to maximize learning outcomes.

Implications for Education and Practice

• Design principles for language instruction across ages:
  • Emphasize high-quality, meaningful input and frequent opportunities for authentic language use.
  • Integrate social interaction, joint attention, and intention-reading activities to support acquisition.
  • Use targeted ISLA approaches (FFI, recasts, explicit feedback) in early schooling to accelerate grammatical accuracy and vocabulary growth.
  • Leverage task-based learning and interactive activities to promote practical usage and motivation.
• For young learners: capitalize on cognitive plasticity and positive attitudes; use pronunciation-focused activities, immersive and playful contexts; provide supportive feedback.
• For older learners and adults: utilize metalinguistic awareness, prior knowledge, and strategic learning techniques; create opportunities for intensive input and sociocultural alignment with the L2 community.
• Translanguaging and bilingual educational benefits:
  • Implement translanguaging practices to maximize comprehension and articulation across languages; support both language and content learning.
  • Address potential systemic constraints by training teachers to value multilingual repertoires and to employ inclusive evaluation methods.
• Pedagogical cautions:
  • Avoid relying solely on native-speaker norms as the sole benchmark for success in L2 attainment.
  • Consider diverse learner goals, contexts, and repertoires when measuring ultimate attainment and language proficiency.

Summary and Conclusion

• Age matters, but it is one of many interacting factors shaping language development.
  • Earlier exposure tends to facilitate certain aspects (pronunciation, morphosyntax), but late learning can achieve high proficiency with high-quality input, motivation, and effective instruction.
  • The critical period concept remains debated; current thinking favors a sensitive-period/gradual-effect view, with age interacting with input, context, and learner strategies.
• Key takeaways across the chapter:
  • First language development proceeds through identifiable stages, with significant variability and strong input/social interaction effects.
  • A range of theoretical perspectives (behaviorist, nativist, connectionist, emergentist, functional/usage-based) contribute to our understanding of language acquisition.
  • In SLA, ultimate attainment is shaped by AoA/AO, LoR, input quality/quantity, motivation, sociocultural factors, and instructional context;
    native-like attainment is possible but not guaranteed, and functional proficiency is a meaningful goal.
  • Child instructed SLA shows that well-designed instruction can accelerate language development, especially when it aligns with developmental needs; younger learners often benefit from high plasticity while older learners leverage metalinguistic skills.
  • Bilingual/multilingual development reveals advantages in executive function and metalinguistic awareness; multicompetence and dynamic systems theory highlight the integrated, evolving nature of multilingual minds; translanguaging offers practical advantages in learning contexts.
• Educational implication: ongoing research supports flexible, input-rich, socially situated, and linguistically inclusive approaches that recognize age-related strengths and the value of multilingual repertoires for teaching and learning.