The thesis investigates ways in which young children acquire meanings of novel words. Various accounts of word learning postulate that the nature of the word exposure context plays a crucial role in supporting lexical acquisition (e.g. Clark. 1997; Nelson, 1988). Children are sensitive to a range of input, such as syntactic cues (Gleitman, 1990), gestures (Kobayashi, 1997) and verbal explanations of word meaning (Dickinson, 1984). The present research aimed to further our understanding of types of word exposure that help children acquire novel words, by examining the process of lexical acquisition in naturalistic contexts. The research was carried out in an educational context; the emphasis was on vocabulary acquisition in the classroom and children's acquisition of science terms, commonly encountered at school. The range of knowledge children acquired about word meanings was assessed using a variety of lexical tasks (e.g. production and comprehension tasks). The research was divided into three phases. Phase 1 focused on the measurement of lexical knowledge. It considered the ways in which drawing-based tasks tap lexical knowledge. Phase 2 evaluated the importance of the word exposure context in lexical acquisition by investigating children's learning of words that were classed as 'difficult' to learn. Finally, phase 3 explored different kinds of word introduction that help children acquire word meanings. This phase of the research was conducted in classroom settings. Drawing assessments were found to make an important contribution to the assessment of lexical knowledge. Findings from phases 2 and 3 showed that ways in which novel words are introduced plays a crucial role in supporting lexical acquisition, and also the range of vocabulary knowledge children acquire (e.g. production and comprehension). Types of exposure that help children acquire words in classroom contexts were identified. The results are discussed in relation to implications for teaching practice and an account of lexical acquisition

Infants struggle to apply earlier-demonstrated sound-discrimination abilities to later word-learning, attending to non-constrastive acoustic dimensions (e.g., Hay et al., 2015), and not always to contrastive dimensions (e.g., Stager & Werker, 1997). One hint about the nature of infants' difficulties comes from the observation that input from multiple talkers can improve word learning (Rost & McMurray, 2009). This may be because, when a single talker says both of the to-be-learned words, consistent talker's-voice characteristics make the acoustics of the two words more overlapping (Apfelbaum & McMurray, 2011). Here, we test that notion. We taught 14-month-old infants two similar-sounding words in the Switch habituation paradigm. The same amount of overall talker variability was present as in prior multiple-talker experiments, but male and female talkers said different words, creating a gender-word correlation. Under an-acoustic-similarity account, correlated talker gender should help to separate words-acoustically and facilitate learning. Instead, we found that correlated talker gender impaired learning of word-object pairings compared with uncorrelated talker gender-even when gender-word pairings were always maintained in test-casting doubt on one account of the beneficial effects of talker variability. We discuss several alternate potential explanations for this effect.

Perceptual processes take time to unfold. Whether a person is processing a visual scene, identifying the category an object belongs to, or recognizing a word, cognitive processes involving competition across time occur. These ongoing competitive processes have been ignored in studies of learning. However, some forms of learning suggest that learning could occur while competition is ongoing, resulting in the formation of mappings involving the competing representations. This dissertation uses word learning as a test case to determine whether such learning exists. In a series of five experiments, participants were taught words under different stimulus and task conditions to encourage or discourage learning during periods of lexical competition. These studies reveal a complex relationship between ongoing lexical competition processes and word learning. Specifically, in cases where learners rely on unsupervised associative learning, they present evidence of learning that is continuous in time, starting during periods of lexical competition and continuing throughout the course of its resolution. These studies offer insight into the nature of associative learning, into the forms of learning that occur when learning new words, and into the ways that task and stimulus structure impinge on how a learner forms new associations.

Word learning implies learning of both a phonological form and its referent. For nouns, the referent is typically a category of objects, with variability between objects within the category but an overlying similarity that allows them to be categorized together, to function similarly, and to be called by the same label. We hypothesized that by strengthening knowledge of the category of referents a word refers to, we could strengthen learning and use of the word. Three-year old children were provided with elaborated referent category information in the form of multiple exemplars of the referent category. In the first manipulation, children were trained on identical exemplars or variable exemplars. A second manipulation provided children with variable exemplars that had been distributed to support a prototype. Children in the third condition, who were provided with a prototype plus variants, learned words best in expressive and receptive tasks, when tested on trained and untrained items, and at two time points. In a second manipulation, we asked if simultaneous presentation of multiple exemplars leads to better learning of the object label than sequential presentation. Results indicated little difference. We conclude that 3-year-olds learn words best in the presence of variability distributed to highlight both invariant elements of the referent category and those elements that are allowed to vary.

Children with cochlear implants (CIs) typically have smaller lexicons in relation to their same-age hearing peers. There is also evidence that children with CIs show slower rates of vocabulary growth compared to hearing children. To understand why children with CIs have smaller vocabularies, we proposed to investigate their word learning process and determine how it compares to children with normal hearing. The present study explores multiple aspects of word learning - acquisition, extension, and retention - to better inform us about the real-world process of lexical acquisition in children with CIs. We evaluated 24 children with cochlear implants, 24 children with normal hearing matched by chronological age, and 23 children with normal hearing who were matched by vocabulary size. Participants were trained and tested on a word learning task that incorporated fast mapping, word extension, and word retention over two days. We also administered a battery of tests that included measures of receptive vocabulary and speech perception skills to determine which variables might be significant predictors of fast mapping and word retention. Children with CIs performed more poorly on word learning measures compared to their age-mates, but similarly to their vocabulary-mates. These findings indicate that children with CIs experience a reduced ability to initially form word-referent pairs, as well as extend and retain these pairs over time, in relation to their same-age hearing peers. Additionally, hearing age-mates and vocabulary-mates showed enhancement in their production of novel words over time, while the CI group maintained performance. Thus, children with CIs may not take the same route in learning new words as typically-developing children. These results could help explain, in part, why this population consistently demonstrates slower rates of vocabulary learning over time. Furthermore, we expected that speech perception and vocabulary size would relate to variations in fast mapping, as well as word retention. Neither of these variables proved to be significant predictors of fast mapping, but they were highly significant for word retention. Based on these findings, we may conclude that the factors that account for acquiring that first link between a word and its referent are not the same as those that are important for storing in a word in long-term memory.

Purpose: Between 13% and 20% of two year olds are late to talk; of those, up to 25% are at risk of persistent language impairment. This highly exploratory study examined whether a dynamic assessment (DA) of single word learning could be used to predict medium term development trajectory and thus provide better information regarding which late talkers were most at risk of continued language delay. Method: Six novel non-words were taught within a scripted play activity, which controlled for number of exposures. Retention and recall of each novel word was tested following both 3 and10 exposures using a predetermined hierarchy of prompts. Participants were 20 typically developing children and 20 late talkers aged 24-29 months. The late talking group (mean age 26 months) was tracked for 8 to 9 months with re-administration of the DA task 3 months after the initial testing. The task employed a graduated prompting framework because it is highly scripted and can be completed within a single brief session; advantageous for screening purposes. Results: Findings indicated that the DA scores for single word learning were associated with change over an 8 to 9 month period. The association between the task and standardised assessment (PLS) change scores was observed to increase over a 3 month period, when the average age of the late talking participants was 29 months. At this time, participants achieving DA scores more closely approximating those of typically developing children were operating within the normal range on standardised testing (PLS) 5 to 6 months later. Conclusions: More accurate differentiation of children who were late blooming versus those likely to be language impaired was achieved closer to 2 ½ years of age. Implications for service provision in terms of directing input to where it is most needed and also in identifying most optimal timing for input are discussed.

Attention impairments are well documented in children with autism spectrum disorders (ASD). Under associative accounts of early word learning, the attention impairments in children with ASD preclude them from developing effective learning strategies. In this study we examined whether children with ASD utilize the same attention cues for learning as their unaffected receptive-vocabulary mates. In a word-learning task, we asked: 1) whether hearing novel and attention-grabbing words cued children to shift their attention to the speaker, and 2) whether the children followed the gaze of the speaker to determine the speaker's focus of attention. We taught novel words in two conditions. One condition provided maximal social-attention scaffolding; the examiner followed the focus of the child's attention. The other was less scaffolded; the examiner directed the child's attention to the target using eye gaze. We manipulated the number of objects present during teaching, two versus four, to examine the effect of non-social attention scaffolding with scaffolding here defined as a reduction in distractions. Fifteen-children with ASD (ages 36-91 months) were matched to fifteen unaffected children (ages 16-92 months) on the basis of receptive vocabulary (RVM group). The ASD group's performance differed from the RVM group's performance on one measure: shifting attention to the speaker upon hearing a novel or attention-grabbing word on the initial trial. On all other measures, the ASD group's performance did not significantly differ from the RVM group's performance. Although there was not a significant effect of condition, closer analysis revealed that in the RVM and ASD groups, only the consistent-gaze followers' performed better than chance on the word-learning tasks. We hypothesize that, when all else is equal, providing a label does not make the target distinct enough to support word-referent pairings for children who are not consistently attending to the speaker. Overall, the ASD group demonstrated greater within group variability in their attention than the RVM group. Gaze following was variable across (and within) the ASD group. The within subject variability suggests some children with ASD are slow to appreciate eye gaze cues in unfamiliar contexts.

This study investigates the role of emotional linguistic input in learning novel words with abstract and concrete denotations. It is widely accepted that concrete concepts are processed more easily than abstract ones. Several theories of vocabulary acquisition additionally propose that learning of concrete concepts puts greater weight on sensorimotor information while abstract concepts put greater weight on emotional information. In this study, proficient adult speakers of English read novel words denoting concrete and abstract concepts (e.g., boat vs religion) embedded in informative passages with different emotional valence (positive, neutral and negative). After five exposures to each novel word in an emotionally consistent context, participants were tested on orthographic and semantic vocabulary learning and provided valence judgments of these novel words. Readers successfully learned orthographic form and meaning of novel words, with a concreteness advantage seen in both tasks measuring semantic learning. Critically, valence of linguistic contexts was more influential for novel words with concrete denotations. In line with previous reports, the transfer of context emotionality to novel words (i.e., semantic prosody) took place in concrete stimuli and not abstract stimuli, even though they were both embedded in emotional contexts. An equal advantage was seen for semantic learning of novel words with both concrete and abstract denotations seen in positive contexts. These findings provide counter-evidence to theories advocating greater reliance of abstract concept learning on emotional information. / Thesis / Master of Science (MSc) / “The girl walked her plurk down the street.” Did you think of a dog? Adults are constantly learning new words by inferring the meaning through context. By making small changes to word and sentence stimuli we can study how semantic properties such as emotion (positive, neutral, or negative) and concreteness (e.g., "lamp" is a physical object that can be touched, making it high in concreteness, while "hope" cannot be touched and is therefore low in concreteness, or abstract) interact. In the current study, we manipulate contexts to vary in emotionality and words to vary in concreteness. Participants read short passages containing new words and were given a surprise test after that measured how well they learned the emotionality, forms, and meanings of the new words. This study presents new insight for theories of how new words are learned and stored in the brain and have implications for language learning materials.

The aim of this study was to examine how providing functional information affects three year olds’ word learning. Previous work has demonstrated that children use perceptual or functional information about an object to aid in word learning. That is, they tend to base word meaning on the shape of the item (e.g., Jones, Smith, & Landau, 1991) or on its function (e.g., Kemler-Nelson et al, 2000). The authors asked whether there were additive effects of functional and perceptual cues on word learning and generalization,either immediately after training, or one to two days later. Thirteen typically developing children were taught four novel words in a play paradigm. They were provided with functional and perceptual information for two of the objects, and given perceptual information only for the other two. The children were exposed to multiple exemplars of each object taught, and allowed to manipulate the items. The children were tested for receptive and expressive knowledge of the words seven to eleven minutes after teaching, and one to two days later.Children did not perform better than chance levels on receptive tasks in any condition, nor did they perform above floor levels on expressive tasks. It is concluded that additional functional information does not enhance word learning for young children in this paradigm.

One goal of applied linguistics is to learn languages better and faster. Second language (L2) learners need to acquire large vocabularies to approach native-like proficiency in their targeted language. A number of studies have explored the factors that facilitate and hinder word learning using highly controlled experiments, however, these lack ecological validity and the findings may not generalize to real-world learning. The studies in this thesis respond to this gap in the literature. The studies leverage big data from a popular language learning app called Lingvist to explore how understudied semantic factors such as valence (positivity/negativity) and concreteness impact adult L2 word learning. Chapter 2 explores the shape of valence effects on learning, the interaction between the semantics of the target word and the linguistic context in which the word is learned, and how these effects unfold over multiple exposures to the target word. Users learn both positive and negative words better than neutral ones, and learning improves by 7% when target words appear in emotionally congruent contexts (i.e., positive words in positive sentences, negative words in negative sentences). These effects are strongest on the learner’s second encounter with the word and diminish over subsequent encounters. Chapter 3 examines the interaction between target word valence and concreteness. Increased positivity increased accuracy for concrete words by up to 13%, but had little impact on learning abstract words. On the theoretical front, findings provide support for embodied cognition, the lexical quality hypothesis, and the multimodal induction hypothesis. On the applied front, they indicate that context valence can be manipulated to facilitate learning and identify which words will be most difficult to learn. / Thesis / Master of Science (MSc) / Language learners need to know tens of thousands of words to communicate fluently in a language. These studies use data from a popular language learning app called Lingvist to understand how the emotionality of words and the sentences we see them in impact learning. Negative words (e.g., murder) and positive words (e.g., vaccation) were learned better than neutral words. Positive words were learned better when they are part of a positive sentence and negative words are learned better in more negative sentences. The second study found that concrete words like brick or table are easier to learn when they are positive, but emotions have little impact on learning abstract words like hope. These findings help researchers understand how words are represented in the mind and point to ways to make language learning faster and easier.