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While late talkers (LTs) are defined by their atypically small expressive vocabularies, far less is known about their receptive vocabularies or how they acquire new words. Some LTs, at least, appear to have receptive deficits (Dale et al., 2003), and in tasks of novel noun learning, LTs are less successful than their typically developing peers (TDs: Ellis Weismer, Venker, Evans, & Moyle, 2013). This dissertation explores LTs’ receptive vocabularies and word-learning, focusing on verb vocabulary. In verb learning, children rely on the linguistic context of the verb as a cue for its meaning (e.g., Naigles, 1990), but children who cannot parse the linguistic context do not learn (He, Kon, & Arunachalam, under revision). This may be particularly challenging for LTs, who are slower lexical processors than TDs (Fernald & Marchman, 2012). The first study (Chapter 2) compares LTs and TDs’ receptive verb vocabularies as measured through eye-tracking and dynamic scene stimuli. It was hypothesized that, as compared to TDs, LTs would know fewer verbs and be slower to process them; however, results of the study do not support either hypothesis. Other group differences were noted, though: As compared to TDs, LTs took longer to demonstrate knowledge of the target vocabulary items, spent less time looking to the target scene, and had greater rates of track loss. Together, these findings indicate subtle differences between LTs and TDs. The second study (Chapter 3) explores children’s capacity to learn novel verb meanings given variable linguistic processing demands. LTs and TDs were introduced to a novel verb, surrounded either only by content nouns or by both content nouns and pronouns. Variability benefits word-learning, and content nouns and pronouns each facilitate different aspects of the acquisition process (Childers & Tomasello, 2001; Hadley, Rispoli, & Holt, 2017; Mintz, 2003). However, variability also incurs a higher processing demand, which was hypothesized to be too great for LTs. Regression analysis revealed that LTs performed significantly worse given variable input as compared to consistent input. This indicates that LTs struggle to learn verb meaning when processing demands are high. The final study (Chapter 4) compares children’s performance on the receptive verb vocabulary task with their performance on the novel verb-learning task. Children who had larger receptive verb vocabularies and faster processing were expected to have learned more verbs during the verb-learning task as compared to children with smaller receptive vocabularies and slower lexical processing. Results of correlation analyses indicate no statistically significant correlations after Bonferroni correction, contrary to prediction. However, they do suggest areas for future research with a priori hypotheses about the relationship between concurrent language abilities and word learning. Taken together, the studies from this dissertation provide new insights into LTs’ verb vocabularies. Future research should continue to explore both between- and within-group differences. This work may ultimately provide insights into why LTs have poorer outcomes as compared to TDs (e.g., Rescorla, 2002; 2005; 2009), and may help identify which LTs are at greatest risk for developmental language disorder (Paul, 1996). / 2021-06-18T00:00:00Z

Non-crying utterances of six 5- to 16-week-old infants recorded in their home environments are analyzed spectrographically for fundamental frequency (F₀) and duration. Biographical and perceptual data are used qualitatively to suggest reasons for intra- and inter-subject variability. Three major statistical analyses were performed: (1) regressions of acoustic features on age, (2) relationship of F₀ and duration, and (3) contrasts of the child's fundamental frequency in different contexts. Not all regressions of acoustic features on chronological age were significant. However, two trends were evident: (1) exponential increase of duration on age and (2) linear increase of within-utterance range on age. With chronological age as a basis for analysis, inter-subject variability was noted even for these trends. Since neither development nor environment are completely uniform within or among children, developmental and social data might provide a firmer basis for analysis in future. The result that children of the same chronological age vocalized differently simply by number of utterances further supports the need for quantitative developmental and social data as analytical criteria. Analysis of fundamental frequency by duration generally showed that frequency range was dependent on amount of fluctuation and duration of utterance. A more complex analysis of the F₀-contour than can be provided spectrographically might yield more definitive information about this relationship. The child's vocal interaction with his environment was analyzed both qualitatively and quantitatively. A frequency count of the number of utterances in different contexts revealed that most children vocalized more when alone than in the presence of an object or person. Hotelling's T² tests of fundamental frequency in different contexts showed further that children did not alter the F₀-contour or within-utterance range of their vocalizations as a response to different objects or situations. However, the fact that twenty percent of the T² tests were significant -- particularly for the most advanced subject -- demonstrates that these children are at least capable of altering their fundamental frequency according to different situations during the early weeks of life. Further research is indicated in this as well as in the other areas. All trends noted in this study will have to be reviewed in the context of the larger project from which the present sample of six subjects was drawn. / Medicine, Faculty of / Audiology and Speech Sciences, School of / Graduate

Fifteen predominantly English-speaking, and nine predominantly French-speaking kindergarten and grade one children served as subjects in an experiment designed to investigate discrimination learning of distinctive features. Stimuli were presented aurally and consisted of (a)meaningful non-linguistic sounds, (b)four Non-Nasalized Vowels, (c)Nasalized equivalents of the Non-Nasalized Vowels. Subjects were required to press one of four response buttons on each trial. Feedback was provided. Testing continued until all subjects had achieved asymptote across all Tasks. Mean probability of a correct response by session was compared for (a) linguistic versus non-linguistic Tasks, (b)Non-Nasalized versus Nasalized Vowels, and (c)the distinctive features characterizing the vowels. Confusion matrices were obtained for inter-vowel confusions. Results shewed that: (a)linguistic stimuli were not as well learned as non-linguistic stimuli, (b)Nasalized Vowels were learned significantly less well than their Non-Nasalized equivalents, and (c)only the distinctive feature ±nasal appeared to correlate with discrimination learning scores. The other features,±round and ±back , did not appear to operate independently in vowel perception. No evidence was obtained to support the hypothesis that one feature is more easily learned than other features within a discrimination learning task, or that a hierarchy governing the perception of distinctive features exists. The youngest children, however, were observed to perform linguistic tasks significantly less well than the older children. The mains effect for linguistic background of subjects was not significant, although significant interactions between this variable and particular tasks were obtained. Vowels best learned by the children were found to be those that elicited the largest number of verbally mediated responses; these were usually onomatopoeic in nature. Analysis of the discrimination learning results was found to be more amenable to interpretation in terms of traditional parameters of the vocal tract than in terms of distinctive features. No one theoretical framework, however, served consistently to explain the perceptual results obtained. / Medicine, Faculty of / Audiology and Speech Sciences, School of / Graduate

Spontaneous production. Imitation, and Comprehension procedures were used to (a) investigate the acquisition of the adjectival relative clause and descriptive adjective, and (b) to examine the predictive adequacy of two performance models, the Yngve Depth Hypothesis and Transformation Hypothesis. Average mean depth and number of transformational operations were used as predictive indices. Subjects were 20 nursery school children, divided into two groups of 10 each, Group 2-3 (mean age 3.6 years) and Group 4-5 (mean age 5.0 years). Subjects were individually tested in three to five sessions on all three procedures and on two tasks within each procedure. Stimuli consisted of two sets of sentences and pictures, Task 1 and Task 2. Task 1 consisted of 36 sentences which varied according to three criteria: Syntax (relative or simple); Embeddedness [end-(2 levels) or self-embedded]; and Pronoun Use (subject, object or object of preposition). Task 2 consisted of 96 sentences which varied according to three criteria: Syntax (adjective, relative or simple); Type of adjective (base or derived); and Embeddedness [end-(3 levels) or self-embedded]. Corresponding to each sentence content was a set of four pictures (Task 1) or pairs of pictures (Task 2) which served as response alternatives during the Comprehension Procedure. Sixty of the pictures were also used as stimulus materials for Spontaneous Production. Dependent measures were number correct (Imitation and Comprehension), latency (Comprehension), number of responses in three error categories (Task 1 Comprehension), and percentage of responses in 12 error categories (Imitation). Spontaneous production results were presented by examples. Age was found to be a highly significant factor in all analyses of number correct for both tasks and procedures, Group 2-3 performing poorer than Group 4-5. On Tasks 1 and 2, Syntax and Embeddedness were significant factors for Imitation but not Comprehension (number correct). On the Task 1 Imitation Procedure, a Simple > Relative ordering of Syntax means was obtained which was consistent with predictions from both models. On Task 2, however, the obtained Adjective > Simple > Relative ordering of Syntax means was consistent with the predictions made from the Depth Hypothesis but not those made from the Transformation Hypothesis. Adjective sentences were expected to be more difficult than Relative according to the latter hypothesis. The finding of poorer performance on self-embedded Relative sentences than on end-embedded or control Simple sentences on Tasks 1 and 2 for Imitation was also consistent with only the Depth Hypothesis, the Transformation Hypothesis predicting no differences since the sentences did not differ in type or number of transformations. Results of the Comprehension and Imitation Procedures allowed for ordering of means according to difficulty but revealed little about the early form of knowledge of single- or multiple-word modifiers. Qualitative analysis of imitation errors and spontaneous production data proved more fruitful. It was found that (1) the Noun Phrase + with + Noun Phrase and Noun Phrase + participle phrase were earlier occurring forms of multiple- word noun modification than the relative clause; (2) the relative clause did not precede the descriptive adjective in production as would be expected on the basis of the Transformation Hypothesis; (3) even the oldest Ss showed little differentiation of the relative pronoun in imitation or spontaneous production; and (4) self-embedded relative clause sentences never occurred in the spontaneous production protocols. Few errors were made in imitation of Adjective sentences or in spontaneous production; all Ss used adjectives in the nominal productively. It was concluded that neither performance model allowed for adequate description or prediction of performance. The Yngve model ignores the relationship between sentences of differing structure and the Transformation model fails to take into account the sequential nature of production and comprehension. Features of a more adequate model were discussed. / Arts, Faculty of / Psychology, Department of / Graduate

This investigation was concerned with reduction in duration of consonants in clusters relative to duration in unclustered contexts. Specifically, the investigation was designed: (a) to determine whether certain consonants' durations were significantly reduced in consonant clusters in adult speech, (b) to determine whether differences in the amount of such reduction existed between age groups, and (c) to determine whether a linear, trend correlating age with amount of consonant reduction existed. Five age groups with five subjects in each group repeated words with initial consonants /s/, /f/, /l/, /w/, /sl/, /fl/, and /sw/. The age groups tested included five-year-olds, seven-year-olds, nine-year-olds, and eleven-year-olds, and an adult control group. Subjects' utterances were recorded and oscillograms of the recordings were measured for consonant duration. Analysis of durations indicated that /s/ and /f/ durations were significantly reduced, in clusters by all age groups but no significant differences between groups existed in amount of reduction of these consonants. Duration of /w/ was not significantly reduced by any age group duration of /l/ was significantly changed by the five-year-old group only. This group lengthened duration of /l/ in clusters. A trend analysis of age correlated with reduction of /l/ demonstrated that amount of reduction of duration of /!/ increases linearly with age between five and eleven years. Consonant reduction was discussed in terms of speech timing programmes. Differences between age groups in consonant duration reduction were discussed in terms of processes observed in children's acquisition of consonant clusters, and possible differences in speech timing programmes used by children and adults. / Medicine, Faculty of / Audiology and Speech Sciences, School of / Graduate

Previous investigations have shown that children between the ages of three and five years give consistently correct responses to requests for one of a pair of quantities which has more elements and incorrect responses to requests for the one containing less. On such a basis it has been hypothesized that the word more is properly understood before the word less and, at some point in the acquisition of these terms, less is understood to have the meaning of more. However, such a response bias is not demonstrable in all of the studies which have required children to deal with the terms more and less. As a consequence, the various experimental methodologies are examined for differences which may have accounted for the disparity of results, i.e., for the presence or absence of the response bias described. The present study investigates the performance of thirty children between the ages of 2; 6 and 4;6 on comparisons which involve the terms more/less and longer/shorter. Two types of comparison were made: (1) the choice of one stimulus in response to the words more and less and longer and shorter, and (2) the choice of one of the terms in the comparison of one stimulus with a given standard. Very few of the children tested demonstrated a response bias in favour of the positive terms, more and longer, and their scores on the comprehension of more and less were found to be highly dependent on the design of the task. The 'Semantic Feature Hypothesis' proposed by E. Clark (1973) suggests that the confusion of polar opposites (i.e., opposing comparative adjectives along the same dimension) is part of a more general principle of semantic development and that all children go through a stage in which the same meaning is attributed to more and less, longer and shorter. The present findings, on the other hand, reveal that almost all the children tested give either consistently correct responses to both terms or inconsistent responses, that children rarely respond consistently incorrectly to either member of the pairs, and that when they do, their performance on a production task indicates either comprehension of both words or non-comprehension of both, but does not support the suggestion that the two words are treated as synonyms. The inadequacy of the tasks used as a measure of comprehension of comparative adjectives constitutes a major difficulty for the 'Semantic Feature Hypothesis', insofar as its formulation was dependent on the assumption that the performance of children in such situations was a valid indication of their understanding of the words in question. The results of the present investigation suggest that such a claim is untenable and that careful control of experimental design is particularly important in the adequate assessment of cognitive-linguistic capabilities. / Medicine, Faculty of / Audiology and Speech Sciences, School of / Graduate