The Effect of Prosody on Distributional Learning in 12‐ to 13‐Month‐Old Infants

Distributional information is a potential cue for learning syntactic categories. Recent studies demonstrate a developmental trajectory in the level of abstraction of distributional learning in young infants. Here we investigate the effect of prosody on infants' learning of adjacent relations between words. Twelve‐ to thirteen‐month‐old infants were exposed to an artificial language comprised of 3‐word‐sentences of the form aXb and cYd, where X and Y words differed in the number of syllables. Training sentences contained a prosodic boundary between either the first and the second word or the second and the third word. Subsequently, infants were tested on novel test sentences that contained new X and Y words and also contained a flat prosody with no grouping cues. Infants successfully discriminated between novel grammatical and ungrammatical sentences, suggesting that the learned adjacent relations can be abstracted across words and prosodic conditions. Under the conditions tested, prosody may be only a weak constraint on syntactic categorization. Copyright © 2011 John Wiley & Sons, Ltd.     

Lexical decision in sentences: Effects of syntactic structure

A lexical decision paradigm was used to examine syntactic influence on word recognition in sentences. Initial fragments of sentences were presented visually (CRT display) one word at a time (at reading speeds), from left to right. The string terminated with the appearance of a lexical decision target. The grammatical structure of the incomplete sentence affected lexical decision reaction time (RT). In Experiment 1, modal verb contexts followed by main verb targets and preposition contexts followed by noun targets produced lower RTs than did the opposite pairings (i.e., modal/noun and preposition/verb). In Experiment 2, transitive verb contexts followed by noun targets and subject noun phrase contexts followed by verb targets yielded lower RTs than did the opposite pairings. Similar contrasts for adjective targets did not yield comparable effects in Experiment 2, but did when the adjective was the head of a predictable phrase (Experiment 4). In Experiment 3, noun targets yielded lower RTs than did verb targets after contexts of a transitive verb followed by a prepositional phrase. An account of these effects is offered in terms of parsing constraints on phrasal categories.     

Structural limits on verb mapping: the role of abstract structure in 2.5‐year‐olds’ interpretations of novel verbs

Two experiments showed that 2.5‐year‐olds, as well as older children, interpret new verbs in accord with their number of arguments. When interpreting new verbs describing the same motion events, children who heard transitive sentences were more likely than were children who heard intransitive sentences to assume that the verb referred to the actions of the causal agent. The sentences were designed so that only the number of noun‐phrase arguments differed across conditions (e.g. She’s pilking her over there versus She’s pilking over there). These experiments isolate number of noun‐phrase arguments (or number of nouns) as an early constraint on sentence interpretation and verb learning, and provide strong evidence that children as young as 2.5 years of age attend to a sentence’s overall structure in interpreting it.     

Utilization of Prosodic Information in Syntactic Ambiguity Resolution

Two self paced listening experiments examined the role of prosodic phrasing in syntactic ambiguity resolution. In Experiment 1, the stimuli consisted of early closure sentences (e.g., “While the parents watched, the child sang a song.”) containing transitive-biased subordinate verbs paired with plausible direct objects or intransitive-biased subordinate verbs paired with implausible direct objects. Experiment 2 also contained early closure sentences with transitively and intransitive-biased subordinate verbs, but the subordinate verbs were always followed by plausible direct objects. In both experiments, there were two prosodic conditions. In the subject-biased prosodic condition, an intonational phrase boundary marked the clausal boundary following the subordinate verb. In the object-biased prosodic condition, the clause boundary was unmarked. The results indicate that lexical and prosodic cues interact at the subordinate verb and plausibility further affects processing at the ambiguous noun. Results are discussed with respect to models of the role of prosody in sentence comprehension.     

Phonological phrase boundaries constrain the online syntactic analysis of spoken sentences

Two experiments tested whether phonological phrase boundaries constrain online syntactic analysis in French. Pairs of homophones belonging to different syntactic categories (verb and adjective) were used to create sentences with a local syntactic ambiguity (e.g., [le petit chien mort], in English, the dead little dog, vs. [le petit chien] [mord], in English, the little dog bites, where brackets indicate phonological phrase boundaries). An expert speaker recorded the sentences with either a maximally informative prosody or a minimally informative one. Participants correctly assigned the appropriate syntactic category to the target word, even without any access to the lexical disambiguating information, in both a completion task (Experiment 1) and an abstract word detection task (Experiment 2). The size of the experimental effect was modulated by the prosodic manipulation (maximally vs. minimally informative), guaranteeing that prosody played a crucial role in disambiguation. The authors discuss the implications of these results for models of online speech perception and language acquisition.     

Young children's use of prosody in sentence parsing

Korean children's ability to use prosodic phrasing in sentence comprehension was studied using two types of ambiguity. First, we examined a word-segmentation ambiguity in which placement of the phrasal boundary leads to different interpretations of a sentence. Next, we examined a syntactic ambiguity in which the same words were differently grouped into syntactic phrases by prosodic demarcation. Children aged 3 or 4 years showed that they could use prosodic information to segment utterances and to derive the meaning of ambiguous sentences when the sentences only contained a word-segmentation ambiguity. However, even 5- to 6-year-old children were not able to reliably resolve the second type of ambiguity, an ambiguity of phrasal grouping, by using prosodic information. The results demonstrate that children's difficulties in dealing with structural ambiguity are not due to their inability to use prosodic information.     

Two-year-olds compute syntactic structure on-line

Syntax allows human beings to build an infinite number of new sentences from a finite stock of words. Because toddlers typically utter only one or two words at a time, they have been thought to have no syntax. Using event-related potentials (ERPs), we demonstrated that 2-year-olds do compute syntactic structure when listening to spoken sentences. We observed an early left-lateralized brain response when an expected verb was incorrectly replaced by a noun (or vice versa). Thus, toddlers build on-line expectations as to the syntactic category of the next word in a sentence. In addition, the response topography was different for nouns and verbs, suggesting that different neural networks already underlie noun and verb processing in toddlers, as they do in adults.     

Context effects in visual word recognition: Lexical relatedness and syntactic context

In three experiments, we investigated how associative word-word priming effects in German depend on different types of syntactic context in which the related words are embedded. The associative relation always concerned a verb as prime and a noun as target. Prime word and target word were embedded in visually presented strings of words that formed either a correct sentence, a scrambled list of words, or a sentence in which the target noun and the preceding definite article disagreed in syntactic gender. In contrast to previous studies (O’Seaghdha, 1989; Simpson, Peterson, Casteel, & Burgess, 1989), associative priming effects were not only obtained in correct sentences but also in scrambled word lists. Associative priming, however, was not obtained when the definite article and the target noun disagreed in syntactic gender. The latter finding suggests that a rather local violation of syntactic coherence reduces or eliminates word-word priming effects. The results are discussed in the context of related work on the effect of gender dis-/agreement between a syntactic context and a target noun.     

Knowing what a novel word is not: Two-year-olds 'listen through' ambiguous adjectives in fluent speech

Three studies investigated how 24-month-olds and adults resolve temporary ambiguity in fluent speech when encountering prenominal adjectives potentially interpretable as nouns. Children were tested in a looking-while-listening procedure to monitor the time course of speech processing. In Experiment 1, the familiar and unfamiliar adjectives preceding familiar target nouns were accented or deaccented. Target word recognition was disrupted only when lexically ambiguous adjectives were accented like nouns. Experiment 2 measured the extent of interference experienced by children when interpreting prenominal words as nouns. In Experiment 3, adults used prosodic cues to identify the form class of adjective/noun homophones in string-identical sentences before the ambiguous words were fully spoken. Results show that children and adults use prosody in conjunction with lexical and distributional cues to ‘listen through’ prenominal adjectives, avoiding costly misinterpretation.     

Effects and Limitations of Prosodic and Semantic Biases on Syntactic Disambiguation

This paper examined the effects of prosody on the syntactic ambiguity resolution of Japanese sentences, especially with reference to the interaction with semantic bias. Syntactically ambiguous sentences with different types of semantic bias were constructed. The degree of bias in each sentence was evaluated through visual presentation experiments. Three types of sentences were selected based on the results of visual presentation experiments, were recorded with prosody maximally favoring each possible interpretation of the sentences, and were used as the stimuli for the auditory presentation experiments. The results showed that prosodic cues can influence the interpretation of a sentence even when the sentence is strongly semantically biased. The results also showed a limitation to prosodic cues. The prosodic biases alone were not sufficient to fully determine the interpretation of the sentences even when the sentences were neutrally biased semantically.     

Prosody and parsing in coordination structures

The effect of prosodic boundary cues on the off-line disambiguation and on-line parsing of coordination structures was examined. It was found that relative clauses were attached to coordinated object noun phrases in preference to second conjuncts in sentences like: The lawyer greeted the powerful barrister and the wise judge who was/were walking to the courtroom. Naive speakers signalled the syntactic contrast between the two structures by a prosodic break between the conjuncts when the relative clause was attached to the second conjunct. Listeners were able to use this prosodic information in both off-line syntactic disambiguation and on-line syntactic parsing. The findings are compatible with a model in which prosody has a strong immediate effect on parsing. It is argued that the current experimental design has avoided confounds present in earlier studies on the on-line integration of prosodic and syntactic information.     

At 11 months,prosody still outranks statistics

English‐learning 7.5‐month‐olds are heavily biased to perceive stressed syllables as word onsets. By 11 months, however, infants begin segmenting non‐initially stressed words from speech. Using the same artificial language methodology as Johnson and Jusczyk (2001 ), we explored the possibility that the emergence of this ability is linked to a decreased reliance on prosodic cues to word boundaries accompanied by an increased reliance on syllable distribution cues. In a baseline study, where only statistical cues to word boundaries were present, infants exhibited a familiarity preference for statistical words. When conflicting stress cues were added to the speech stream, infants exhibited a familiarity preference for stress as opposed to statistical words. This was interpreted as evidence that 11‐month‐olds weight stress cues to word boundaries more heavily than statistical cues. Experiment 2 further investigated these results with a language containing convergent cues to word boundaries. The results of Experiment 2 were not conclusive. A third experiment using new stimuli and a different experimental design supported the conclusion that 11‐month‐olds rely more heavily on prosodic than statistical cues to word boundaries. We conclude that the emergence of the ability to segment non‐initially stressed words from speech is not likely to be tied to an increased reliance on syllable distribution cues relative to stress cues, but instead may emerge due to an increased reliance on and integration of a broad array of segmentation cues.     

Young Mandarin learners use function words to distinguish between nouns and verbs

Mandarin requires neither determiners nor morphological inflections, which casts doubt on Mandarin‐speaking children's ability to use function words as a syntactic bootstrapping tool to identify the form class of a new word. This study examined 3‐ and 5‐year‐old Mandarin learners' ability to use function words to interpret new words as either nouns or verbs in the absence of the requirement for determiners and inflections in the ambient language. In Experiment 1, 3‐, and 5‐year‐old Mandarin‐speaking children were exposed to eight novel words embedded in sentence frames differing only in the form class markers used. The 5‐year‐olds interpreted the novel words as either nouns or verbs depending on the form class markers they heard, while the 3‐year‐olds learned only the nouns. Experiment 2 confirmed that the 5‐year‐olds understood the function of the verb‐marker. Thus, Mandarin‐speaking children can use function words to distinguish nouns versus verbs, and this ability appears between three and five years of age.     

The Understanding of Word Definitions in School-Age Children

This study investigated children’s understanding of unfamiliar noun and verb definitions in tasks that were manipulated for syntactic and semantic properties of definitions. The study was also designed to examine the relation between understanding word definitions and the skills of syntactic awareness and making inferences. A total of 117 children over three upper elementary grades (3, 4, 5) participated in the study. The definitional tasks were presented in multiple choice format, with each definition followed by four context sentences. In the syntactic/semantic condition, which included nouns and verbs, the context sentences were manipulated for syntactic and semantic properties. In the semantic condition, which included only nouns, the context sentences were manipulated only for semantics. All children also completed a syntactic awareness task and a making inferences task. Results indicated that children did not make significant grade improvements in the semantic task, but did so in the syntactic/semantic task, suggesting the dependence of syntactic cues on definitional understanding. Findings further suggested that inferencing and syntactic awareness are important to children’s ability in understanding a definition for an unfamiliar word and to integrating that meaning into a context sentence.     

Familiar words can serve as a semantic seed for syntactic bootstrapping

Young children can exploit the syntactic context of a novel word to narrow down its probable meaning. But how do they learn which contexts are linked to which semantic features in the first place? We investigate if 3‐ to 4‐year‐old children (n = 60) can learn about a syntactic context from tracking its use with only a few familiar words. After watching a 5‐min training video in which a novel function word (i.e., ‘ko’) replaced either personal pronouns or articles, children were able to infer semantic properties for novel words co‐occurring with the newly learned function word (i.e., objects vs. actions). These findings implicate a mechanism by which a distributional analysis, associated with a small vocabulary of known words, could be sufficient to identify some properties associated with specific syntactic contexts.     

Human Learning on a Four-Section,Elevated, Finger Maze

Forty Ss learned 10 sentences composed of adjective, noun, verb, and adverb and were subsequently tested for their recall of the sentences and their ability to generate new sentences based on an association rule for words within the sentences. The rule could be discovered from the sentences learned and was comparable to grammatical rules for sentence structure. Subjects also rated the meaning of the words from the sentences before and after learning. Eight Ss were in each of five experimental conditions, which differed in terms of the degree to which the words in the 10 sentences were in a natural language order. The five orders were natural, reversed, 20% random, 50% random, and 100% random orders.

The results showed that the closer the sentence order was to natural language order, the more Ss recalled the sentences they learned and the more accurately they generated unlearned sentences, apparently as a result of discovering and using the association rule. Another finding was that the rated evaluative meaning of words changed in a predictable direction, toward the mean rating of the words associated with each word. Such meaning conditioning appears to be an automatic process comparable to classical conditioning in that it is unaffected by the order of words within sentences and occurs for different word forms.     

Planning at the Phonological Level during Sentence Production

In two picture–word interference experiments we examined whether phrase boundaries affected how far in advance speakers plan the sounds of words during sentence production. Participants produced sentences of varying lengths (short determiner + noun + verb or long determiner + adjective + noun + verb) while ignoring phonologically related and unrelated words to the verb of the sentence. Response times to begin producing both types of sentences were faster in the presence of a related versus unrelated distractor. The results suggest that the activation of phonological properties of words outside the first phrase and first and second phonological word affect onset of articulation during sentence production. The results are discussed in the light of previous evidence of phonological planning during multi-word production. Implications for the phonological facilitation effect in the picture–word interference paradigm are also discussed.The research reported in this article served as partial fulfillment of the requirements for the PhD degree at Harvard University for Tatiana T. Schnur     

The influence of prosodic structure on the resolution of temporary syntactic closure ambiguities

This paper investigates the influence of prosodic structure on the process of sentence comprehension, with a specific focus on the relative contributions of syntactic and prosodic information to the resolution of temporary syntactic closure ambiguities. We argue that prosodic structure provides an initial memory representation for spoken sentences, and that information from this prosodic representation is available to inform syntactic parsing decisions. This view makes three predictions for the processing of temporary syntactic ambiguity: 1. When prosodic and syntactic boundaries coincide, syntactic processing should be facilitated. 2. When prosodic boundaries are placed at misleading points in syntactic structure, syntactic processing should show interference effects. 3. The processing difficulties that have been reliably demonstrated in reading experiments for syntactically complex sentences should disappear when those sentences are presented with a felicitous prosodic structure in listening experiments. These predictions were confirmed by series of experiments measuring end-of-sentence comprehension time and cross-modal naming time for sentences with temporary syntactic closure ambiguities. Sentences with coinciding or conflicting prosodic and syntactic boundaries were compared to a prosodic baseline condition.This research was supported in part by NIMH grant R29 MH51768 to the first author and NIMH grant T32 MH19729 to the Northeastern University Psychology Department.     

The role of grammatical class on word recognition

The double dissociation between noun and verb processing, well documented in the neuropsychological literature, has not been supported in imaging studies. Recent imaging studies, in fact, suggest that once confounding with semantics is eliminated, grammatical class effects only emerge as a consequence of building frames. Here we assess this hypothesis behaviorally in two visual word recognition experiments. In Experiment 1, participants made lexical decisions on verb targets. We manipulated the grammatical class of the prime words (either nouns or verbs and always introduced in a minimal phrasal context, i.e., “the + N” or “to + V”), and their semantic similarity to a target (related vs. unrelated). We found reliable effects of grammatical class, and no interaction with semantic similarity. Experiment 2 further explored this grammatical class effect, using verb targets preceded by semantically unrelated verb vs. noun primes. In one condition, prime words were presented as bare words; in the other, they were presented in the minimal phrasal context used in Experiment 1. Grammatical class effects only arose in the latter but not in the former condition thus providing evidence that word recognition does not recruit grammatical class information unless it is provided to the system.     

The minimal unit of phonological encoding: prosodic or lexical word

Wheeldon and Lahiri (Journal of Memory and Language 37 (1997) 356) used a prepared speech production task (Sternberg, S., Monsell, S., Knoll, R. L., & Wright, C. E. (1978). The latency and duration of rapid movement sequences: comparisons of speech and typewriting. In G. E. Stelmach (Ed.), Information processing in motor control and learning (pp. 117-152). New York: Academic Press; Sternberg, S., Wright, C. E., Knoll, R. L., & Monsell, S. (1980). Motor programs in rapid speech: additional evidence. In R. A. Cole (Ed.), The perception and production of fluent speech (pp. 507-534). Hillsdale, NJ: Erlbaum) to demonstrate that the latency to articulate a sentence is a function of the number of phonological words it comprises. Latencies for the sentence [Ik zoek het] [water] 'I seek the water' were shorter than latencies for sentences like [Ik zoek] [vers] [water] 'I seek fresh water'. We extend this research by examining the prepared production of utterances containing phonological words that are less than a lexical word in length. Dutch compounds (e.g. ooglid 'eyelid') form a single morphosyntactic word and a phonological word, which in turn includes two phonological words. We compare their prepared production latencies to those syntactic phrases consisting of an adjective and a noun (e.g. oud lid 'old member') which comprise two morphosyntactic and two phonological words, and to morphologically simple words (e.g. orgel 'organ') which comprise one morphosyntactic and one phonological word. Our findings demonstrate that the effect is limited to phrasal level phonological words, suggesting that production models need to make a distinction between lexical and phrasal phonology.