9 (143) Morphological and Syntactic Development Study Guide

Developmental Vocabulary Trajectories and Change

Timeline of Word Acquisition: * By 12 Months (Concrete Stage): Vocabulary is dominated by labels for physical entities and people. Examples: "mommy," "hi," "bottle," "telephone," "cup." * By 20 Months (Concrete Relational Stage): Children begin incorporating actions and relational terms. Examples: "go," "sit," "hug," "hand," "big," "up." * By 30+ Months (Abstract and Grammatical Stage): Integration of function words and internal state terms. Examples: "by," "around," "think."
Conceptual Ordering: Nouns are generally acquired before verbs. Concrete verbs are acquired before abstract verbs, even in environments where children hear verbs more frequently.
Explaining Trajectories: * Contingent Acquisition: This theory suggests it is a logical necessity to learn concrete words first. Acquiring concrete vocabulary allows children to learn sentence structures, which they subsequently use to decode more abstract or relational meanings. * Cognitive Development: This theory posits that young children initially have a conceptual difficulty understanding abstract or relational concepts, regardless of linguistic input.
Comparative Vocabulary Studies (Adoptees vs. EFL): * Research indicates that the proportion of nouns decreases as the overall vocabulary size increases. * Comparative data between adoptees (green) and EFL (English as a Foreign Language) toddlers (blue) shows a consistent trend: as vocabulary reaches a size of $100$ to $700$ words, the proportion of nouns drops from approximately $0.6$ to $0.4$ . * A study by Naigles (1990) indicates that 2-year-olds can use syntax to learn verb meanings. In an experiment with a Transitive and Intransitive condition involving two simultaneous actions, the sentence structure biased the children’s interpretation of the verb's meaning.

Devices for Morphological Development

1. Inflectional Rules: These involve bound morphemes (affixes like "-ed" or "-ing") that create grammatical variants of the same word. They are used to mark tense, number, and other grammatical categories.
2. Derivational Rules: Bound affixes create entirely new words from existing ones, often changing the meaning or the part-of-speech. * -ness (Adjective-to-Noun): slow $ightarrow$ slowness. * -ize (Adjective-to-Verb): modern $ightarrow$ modernize. * -ish (Adjective-to-Adjective): red $ightarrow$ reddish. * -ly (Adjective-to-Adverb): personal $ightarrow$ personally. * -al (Noun-to-Adjective): recreation $ightarrow$ recreational. * -fy (Noun-to-Verb): glory $ightarrow$ glorify. * -able (Verb-to-Adjective): drink $ightarrow$ drinkable.
3. Compounding: This involves creating words composed of multiple free morphemes. * Noun-Noun: football. * Adjective-Noun: blackboard. * Verb-Noun: whirlpool. * Preposition-Noun: underworld.

Order of Morphological Acquisition in English (Brown & Cazden, 1968)

The Sequential Order: 1. Present progressive ("singing"). 2. Prepositions ("in" and "on"). 3. Plural ("books"). 4. Irregular Past Tense ("went"). 5. Possessive ("Mommy’s chair"). 6. Articles ("the" and "a"). 7. Regular past tense ("walked"). 8. Third person present ("he climbs"). 9. Auxiliary uncontractable ("She was here"). 10. Auxiliary contractable ("She’s going to school").
Predicting Factors: The order is influenced by five factors: * Number of allophones corresponding to the morpheme (e.g., $/s/$ vs. $/z/$ for plural). * Regularity of the rule. * Frequency of the pattern in the child’s input. * Semantic complexity. * Syntactic complexity.

The Controversy of Rule Learning: Regular vs. Irregular Forms

The Case Study of Past Tense Verbs: Do children learn each variant individually or apply rules? * Hypothesis 1: All Rules: Both regular (walk-ed) and irregular (ring-rang) patterns are rule-driven (e.g., the $i-a$ rule for drink-drank). However, irregular patterns contain many exceptions (e.g., think-thank is incorrect). Hypothesis 2: Words and Rules Model (Pinker, 1991): Regular inflections are derived by rule, whereas irregular inflections are memorized words stored in the lexicon.
Mechanism of Pinker's Model: * Lexicon and grammar are accessed in parallel. * If an irregular form (e.g., "held") is found in memory, it blocks the application of the general past-tense rule. * If no irregular form is found, the general "-ed" rule is applied (e.g., "walk-ed").
Empirical Evidence for the Words and Rules Model: * Frequency Dependence: The top 13 most frequent verbs in English are irregular (be, have, do, say, etc.). * Historical Regularization: Low-frequency irregular verbs are regularized over time because they are harder to retrieve from memory (e.g., "slew" $ightarrow$ "slayed," "trod" $ightarrow$ "treaded"). Liberman et al. (2007) mapped this across Old, Middle, and Modern English. * Generalization Patterns: Adults and children are more likely to extend irregular patterns based on similarity (spring $ightarrow$ splang, by analogy to ring $ightarrow$ rang), whereas regular rules do not require similarity.

Clinical and Neurological Correlations for Morphology

Alzheimer’s Disease (AD): Patients suffer medial/neocortical temporal lobe degeneration (anomia). They have more trouble inflecting irregular than regular verbs.
Parkinson’s Disease (PD): Associated with basal ganglia degeneration. PD patients (agrammatic) show the contrasting pattern: more trouble with regular rules than memorized words.
Huntington’s Disease (HD): Patients show a pattern of "disinhibition" in frontal areas, resulting in unsuppressible regular suffixation (e.g., producing errors like "walkeded" or "dugged," but not irregular errors like "keepet").
Aphasia Studies: * Agrammatic non-fluent aphasics: Better with irregular inflections ( $98\%$ correct) than regular/over-regularized inflections ( $20\%$ correct). * Anomic fluent aphasics (JLU): Better with regular inflections ( $99\%$ correct) than irregular inflections ( $90\%$ correct).

Overregularization and Creative Language Use

Overregularization Frequency: The actual rate is low, approximately $4\%$ . It is defined as: $\frac{\text{overregularizations}}{\text{overregularizations} + \text{correct past tense forms}}$ .
Theoretical Explanations: * Rule Replacement: The child learns the rule and it replaces learned irregulars until they are reacquired as exceptions. * Memory Limitations (Words and Rules): Children have the irregular form in memory but fail to retrieve it, defaulting to the rule. Even adults regularize when memory fails.
Creative Morphology (Clark, 1982): Children create new words to fill gaps. * New Compounds: "plate-egg" (fried egg), "fix-man" (mechanic). * New Nouns: "lessoner" (teacher), "driver" (car key). * New Adjectives: "toothachey." * New Verbs from Nouns: "broom it" (sweep), "scale it" (weigh it).

Introduction to Syntax and Phrase Structure

Hypothesis 1: Word-Chain Devices (Linear Strings): * Based on Transitional Probabilities (TPs) as a stimulus-response chain. * Problems: Long-distance dependencies (e.g., "Either…or"); "Daddy, what did you bring that book…up for?"; and structural ambiguity (e.g., "more intelligent leaders" can mean "more [intelligent leaders]" or "[more intelligent] leaders").
Hypothesis 2: Phrase Structure Grammar (Hierarchy): * Sentences are represented by hierarchical symbols. * Rules: $S \rightarrow NP\,VP$ , $NP \rightarrow Det\,N$ , $VP \rightarrow V\,NP$ . * Properties: 1. Productivity: New words (e.g., "dax") inherit category behavior. 2. Recursion: Rules can invoke themselves (e.g., "I know that John said that Mary believed…"). 3. Ambiguity Solution: Grouping words into phrases clarifies meaning (e.g., "The man saw the boy with the telescope" can have two tree structures depending on who has the telescope).
Phrase Anatomy: * Head: The core word that determines the phrase type and constraints (e.g., "cat" in "the cat in the hat"). * Arguments: These typically follow the head in English ( $V\,NP$ , such as "eat the cake"). * Specifiers: These qualify the head and precede it in English (e.g., determiners like "the" in "the books").

Theories of Syntax Acquisition

Nativist: Principles and Parameters (Chomsky): * Syntactic categories are universal/innate. Variations occur via parameters (e.g., Head-first vs. Head-last). * Semantic Bootstrapping (Pinker): * Step 1: Use innate linking rules (Animate = Noun, Action = Verb). * Step 2: Distributional analysis to cluster other words. * Step 3: Assign syntactic functions (Subject, Object) based on semantic roles (Agent, Patient). * Step 4: Set language-specific parameters.
Constructivist Approach: * Language begins with item-specific knowledge ("Verb Islands"). * Children build abstract rules via analogy and domain-general learning (statistical learning). * "Smart" Distributional Learning: Tracking morphological properties to form categories without innate templates.

Developmental Evidence and Studies

Valian (1986): Examined transcripts for errors of commission. Children aged 2-2.5 show high correctness with determiners, not placing them after adjectives or nouns, or in pairs.
Tomasello & Brooks (1998): Tested if 2- and 3-year-olds would use a novel intransitive verb ("tamming") transitively. Findings showed high conservativity in toddlers; they rarely generalized verbs to new constructions.
Gertner, Fisher & Eisengart (2006): Comprehension task with 21- and 25-month-olds. Children heard a novel verb ("gorping") in a transitive sentence. Results indicated toddlers look longer at the causal agent, suggesting they possess abstract knowledge of word order (Subject = Agent) earlier than production might suggest.
Conclusion: Between ages 2 and 3, children show abstract syntactic knowledge, though they still must learn specific constraints (e.g., "The ball rolled" is okay, but "*He fell the ball" is not).