Why are some verbs learned before other verbs? Effects of input frequency and structure on children's early verb use.

This study investigated the extent to which the nature of verb input accounts for the order in which children acquire verbs. We assessed the nature of verb input using a combined sample of the speech of 57 mothers addressing their Stage I children. We assessed the order of verb acquisition using as our database a combined sample of those children's speech 10 weeks later and using as our measure of order of acquisition the frequency of verb occurrence. The first set of analyses established the validity of this measure of acquisition order by comparing it with order of acquisition data obtained from checklist and diary data. The second set of analyses revealed that three properties of the input were significant predictors of the order of acquisition of the 25 verbs that were the focus of this study. The predictive properties of input were the total frequency, final position frequency, and diversity of syntactic environments in which the verbs appeared. These findings suggest that the way verbs appear in input influences their ease of acquisition. More specifically, the effect of syntactic diversity in input provides support for the syntactic bootstrapping account of how children use structural information to learn the meaning of new verbs.

Caregiver speech and children's use of nouns versus verbs: a comparison of English, Italian, and Mandarin.

This paper examines naturalistic samples of adult-to-child speech to determine if variations in the input are consistent with reported variations in the proportions of nouns and verbs in children's early vocabularies. It contrasts two PRO-DROP languages, Italian and Mandarin, with English. Naturalistic speech samples from six 2:0 English-, six 1:11 Italian-, and ten 1:10 Mandarin-speaking children and their caregivers were examined. Adult-to-child speech was coded for the type frequency, token frequency, utterance position, and morphological variation of nouns and verbs as well as the types and placements of syntactic subjects and the pragmatic focus of adult questions. Children's spontaneous productions of nouns and verbs and their responses to adult questions were also examined. The results suggest a pattern consistent with the children's spontaneous production data. Namely, the speech of English-speaking caregivers emphasized nouns over verbs, whereas that of Mandarin-speaking caregivers emphasized verbs over nouns. The data from the Italian-speaking caregivers were more equivocal, though still noun-oriented, across these various input measures.

The use of multiple frames in verb learning via syntactic bootstrapping.

Following the original Syntactic Bootstrapping proposal of Landau and Gleitman (1985), this study investigated whether young 2-year-old children (mean age = 28 months) can use multiple syntactic frames, in addition to the extralinguistic scene, to help focus on the meaning of a novel verb. The multiple frames tested were combinations of transitive and intransitive frames in two alternation patterns, Causative and Omitted Object. By hypothesis, the Causative alternation would be more predictive of actions involving physical causation and the Omitted Object alternation more predictive of actions involving repeated physical contact without causation. Subjects were presented with videos depicting both actions, together with a novel verb. The actions were subsequently separated, and the children were asked to select which action was the referent of the novel verb. The novel verb was presented either in transitive and intransitive frames in the Causative alternation (CS: The duck is sebbing the frog, the frog is sebbing) or the Omitted Object alternation (OO: The duck is sebbing the frog, the duck is sebbing), or in intransitive frames only (IO: The duck is sebbing), or without a frame (FF: Sebbing!). In the CS, IO, and FF conditions, children preferred the causative action as the referent of the verb. However, the girls in the OO condition showed a significantly different preference, and looked more toward the contact actions than their peers in the other conditions did. This study thus provides the first experimental evidence that young 2-year-old children can use multiple syntactic frames to help determine the meaning of a novel verb.

Overextensions in comprehension and production revisited: preferential-looking in a study of dog, cat, and cow.

This study investigated overextensions in comprehension and production using a new method (the preferential-looking paradigm) in which children (N = 99, mean age (younger) = 1;9, mean age (older) = 2;3) were asked to find the referent that matched the label they were given. Both Real Referent (in which there was a match) and Anomalous (in which there was no match) trials were included, as well as nonverbal control trials. During the Real Referent trials, all children significantly preferred the matching puppet. During the Anomalous trials, children showed no preference with two of the labels (dog and cat); however, they did show a preference when 'cow' was requested but not available. There were no differences based on prior overextension performance in production. It is concluded that overextensions in production are not diagnostic of children's underlying semantic representations, and that anomalous trials in comprehension provide useful information concerning young children's lexical entries.

First contact in verb acquisition: defining a role for syntax.

The goal of this research was to address 2 questions regarding children's use of syntactic information in acquiring verbs: First, what are children's biases for actions in the absence of syntactic information; and second, how specific is the meaning derived for verbs when syntactic information is present? In 3 experiments we presented nonsense verbs either in syntactic isolation (e.g., "Look! Sebbing!") or embedded within a transitive syntactic frame (e.g., "The frog is sebbing the duck"). These actions were then separated, and the children (mean age = 2 years, 3 months) were asked to select the action which was the referent of the verb. In Experiment 1, Causative actions (in which 1 character forces another to move in some way) were paired with Synchronous actions (in which both characters move simultaneously). In Experiment 2, the same Synchronous actions were now paired with Contact actions (in which 1 character merely touches the other). In Experiment 3, the Contact actions were paired with Causative ones. 2 results emerged: (1) Children have identifiable action biases in the absence of syntactic information and (2) these biases can be shifted by the addition of a transitive syntactic frame. We conclude that the meaning derived from the transitive frame is not specifically Causative or Contact but, more generally, a sense that 1 character is affecting another.

Children use syntax to learn verb meanings.

Verb learning is clearly a function of observation of real-world contingencies; however, it is argued that such observational information is insufficient to account fully for vocabulary acquisition. This paper provides an experimental validation of Landau & Gleitman's (1985) syntactic bootstrapping procedure; namely, that children may use syntactic information to learn new verbs. Pairs of actions were presented simultaneously with a nonsense verb in one of two syntactic structures. The actions were subsequently separated, and the children (MA = 2;1) were asked to select which action was the referent for the verb. The children's choice of referent was found to be a function of the syntactic structure in which the verb had appeared.