This thesis suggests that the range of vocabulary in an individual’s lexicon has an influence on in their assessment of nonword wordlikeness. The study included thirteen Spanish-English bilinguals who participated in a language dominance questionnaire, standardized assessments of Spanish and English vocabulary knowledge, and Spanish and English wordlikeness judgment tasks. Resulting data demonstrated moderate correlations between vocabulary knowledge and performance on nonword wordlikeness judgement tasks in Spanish and English. Participants with larger lexicons appeared more tolerant of less probable nonwords, those with low phonotactic probability, while those with smaller lexicons were less accepting of nonwords with low phonotactic probability. The results suggest that an individual’s processing of low probability phonological constituents is influenced by the diversity and complexity of their linguistic knowledge and specifically, their vocabulary acquisition.

The current research examined whether nonword repetition (NWR) tasks, designed to measure phonological short-term memory, are also influenced by familiarity with lexical representation of a given language. In Study 1, children with and without exposure to Hebrew were administered a NWR task based on the Hebrew language structure (HNWR). On the HNWR, participants with Hebrew exposure significantly outperformed participants who had no familiarity with any Semitic language. This indicates that long-term phonological and lexical knowledge can be used to aid NWR performance. Study 2 investigated whether a NWR task based on a foreign language could minimize the lexicality effect. English speaking undergraduate students rated the less familiar HNWR task to be lower in wordlikeness than English-like NWR tasks. These findings demonstrate that regardless of language background a NWR task based on an unfamiliar language structure is a more valid measure of the phonological processing skills required for vocabulary acquisition.

The current research examined whether nonword repetition (NWR) tasks, designed to measure phonological short-term memory, are also influenced by familiarity with lexical representation of a given language. In Study 1, children with and without exposure to Hebrew were administered a NWR task based on the Hebrew language structure (HNWR). On the HNWR, participants with Hebrew exposure significantly outperformed participants who had no familiarity with any Semitic language. This indicates that long-term phonological and lexical knowledge can be used to aid NWR performance. Study 2 investigated whether a NWR task based on a foreign language could minimize the lexicality effect. English speaking undergraduate students rated the less familiar HNWR task to be lower in wordlikeness than English-like NWR tasks. These findings demonstrate that regardless of language background a NWR task based on an unfamiliar language structure is a more valid measure of the phonological processing skills required for vocabulary acquisition.

Phonotactic processing is foundational to the word processing task in both monolingual and bilingual children (Li & Farkas, 2002; Pierrehumbert, 2001; Shook & Marian, 2013; Storkel & Morrisette, 2002). While the use of phonotactic information in word processing in monolingual children is relatively well documented, it is less well understood in bilingual children. The purpose of this study was to investigate how bilingual kindergartners process the phonotactic probabilities of their two languages. A set of nonwords was developed that manipulated the strength of phonotactic probability across both Spanish and English while also controlling the language environment of the experimental task (i.e., whether children were tested in Spanish or English). Hence, this study allowed for a unique investigation into how bilingual children process two languages and their associated phonotactic probabilities. Specifically, this study provided answers to: whether or not bilingual children benefitted from a high probability processing advantage, if the phoneme systems of two languages were stored as one unit or separate units, and if there was an effect of language environment (i.e., an assimilation effect, Burki-Cohen et al., 1989). By varying the phonotactic probabilities of nonwords and the language environment), the answers to several research questions were sought. First, language exclusive nonwords (nonwords that had phonotactic probabilities unique to English or Spanish) were used to investigate the presence of a high phonotactic probability processing advantage in bilingual children. Second, high/low nonwords (nonwords with a high phonotactic probability in one language and a low phonotactic probability in the other language) were compared with the language exclusive nonwords to determine if the phonotactic systems of a bilingual child's two languages are stored together such that they interact during word processing. Finally, ambiguous nonwords (those with equal phonotactic probability in both languages) were used to investigate the influence of language environment on phonotactic processing. The nonwords were created by manipulating phonotactic probabilities in each language, recorded by two bilingual speakers, standardized for fundamental frequency and synthesized to become phonetically and acoustically ambiguous. Wordlikeness judgments in each language were obtained from monolingual English and bilingual Spanish-English adults. These results determined that adults were processing the varying phonotactic probabilities of the nonwords as designed and the words were appropriate stimuli for use in a word sorting task with bilingual children. In an attempt to replicate aspects of a natural language environment, the current study first divided children into two bilingual testing groups: one where mostly English was spoken and another where mostly Spanish was spoken. Children watched cartoons illustrating the need for sorting nonwords into two languages before completing the word sorting tasks. The experiment was presented using MouseTracker (Freeman, 2011), which recorded the participant's response and mouse cursor movement (as a measure of decision complexity) as the child selected either Spanish or English. Mixed level modeling results indicated significant differences in language choice but not decision complexity across the nonword types. First, bilingual children sorted language exclusive nonwords by focusing on whether the word was more probable in English or Spanish than whether the nonword had high or low probability within a language. Hence, these participants did not appear to benefit from a high phonotactic processing advantage. When children were sorting the high/low nonwords, they tended to ignore the fact that the nonwords had phonotactic probability in both languages, and treated them as belonging to the language in which they had the highest phonotactic probability. This finding would suggest that bilingual children do not appear to store the phonotactic systems of two languages together. Finally, results showed no effect of language environment when children were sorting the ambiguous nonwords. Overall, it appears that bilingual children focus on the overall phonotactic probability of a nonword (i.e., whether it is more probable in Spanish or English) during processing, while ignoring any dual phonotactic probabilities from two languages. These results are incorporated within a proposed model of bilingual word processing and a brief discussion of how these findings can be expanded to explain bilingual word learning is provided.

Nonword repetition tasks were originally devised to assess the efficiency of the phonological loop (Baddeley & Hitch, 1974), a component of the working memory system, where verbal information is temporarily stored and translated to support activities like phonological processing during early word-recognition (Snowling, 1981; Wagner et al., 2003), speech production (McCarthy & Warrington, 1984), and articulation (Watkins, Dronkers, & Vargha-Khadem, 2002; Yoss & Darley, 1974). From a practical perspective, there is a significant need for a systematically-designed Spanish nonword repetition measure that is equivalent to currently-available English measures. For this study, a database of nonwords that considered phonotactic and phonological properties of Spanish was devised. In a preliminary study, Spanish-speaking adults provided wordlikeness judgments about a large set of candidate nonwords. A subset of the rated nonwords was used in the development of a Spanish nonword repetition measure. The aim of the main experiment was to explore the contributions of participant factors (age, gender, and vocabulary knowledge) and item factors (word length, stress pattern, and wordlikeness) to Spanish repetition performance in this group of Spanish speaking, English language learning children. From a theoretical perspective, this investigation allowed a first observation of how experience with listening to and producing Spanish words influences the acquisition of Spanish-specific phonological patterns. A total of 68 children, ages four to six years with varying degrees of Spanish language knowledge participated in this study. Results revealed significant age and word length effects. However, stress pattern did not exert significant effects on repetition performance, which is not completely consistent with previous literature. That is, participants repeated nonwords from both the more frequent and the less frequent stress pattern with similar accuracy. Wordlikeness, a previously uninvestigated variable in nonword repetition was found to affect repetition accuracy. For all participants, nonwords rated as high in wordlikeness were more accurately repeated than were nonwords with low wordlikeness ratings. Findings of the study are discussed in terms of how they relate to working memory and usage-based models of phonological learning. Finally, the clinical relevance of nonword repetition in the assessment of coarse- and fine-grained mappings of phonological knowledge is suggested.