The present paper explores nonnative (L2) phonological encoding of lexical entries and dissociates the difficulties associated with L2 phonological and phonolexical encoding by focusing on similarly sounding L2 words that are not differentiated by difficult phonological contrasts. We test two main claims of the fuzzy lexicon hypothesis: (1) L2 fuzzy phonolexical representations are not fully specified and lack details at both phonological and phonolexical levels of representation (Experiment 1); and (2) fuzzy phonolexical representations can lead to establishing incorrect form-to-meaning mappings (Experiment 2). The Russian-English Translation Judgment Task (Experiment 1, TJT) explores how the degree of phonolexical similarity between a word and its lexical competitor affects lexical access of Russian words. Words with smaller phonolexical distance (e.g., parent–parrot) show longer reaction times and lower accuracy compared to words with a larger phonolexical distance (e.g., parent–parchment) in lower-proficiency nonnative speakers, and, to a lesser degree, higher-proficiency speakers. This points to a lack of detail in nonnative phonolexical representations necessary for efficient lexical access. The Russian Pseudo-Semantic Priming task (Experiment 2, PSP) addresses the vulnerability of form-to-meaning mappings as a consequence of fuzzy phonolexical representations in L2. We primed the target with a word semantically related to its phonological competitor, or a potentially confusable word. The findings of Experiment 2 extend the results of Experiment 1 that, unlike native speakers, nonnative speakers do not properly encode phonolexical information. As a result, they are prone to access an incorrect lexical representation of a competitor word, as indicated by a slowdown in the judgments to confusable words. The study provides evidence that fuzzy phonolexical representations result in unfaithful form-to-meaning mappings, which lead to retrieval of incorrect semantic content. The results of the study are in line with existing research in support of less detailed L2 phonolexical representations, and extend the findings to show that the fuzziness of phonolexical representations can arise even when confusable words are not differentiated by difficult phonological contrasts.

This paper begins by discussing new trends in the use of neurostimulation techniques in cognitive science and learning research, as well as the nascent research on their application in second language learning. To illustrate this, an experiment designed to investigate the impact of transcutaneous vagus nerve stimulation (tVNS), which is delivered via earbuds, on how learners process and learn Mandarin tones is reported. Pupillometry, which is an index of cognitive effort, is explained and illustrated as one way to assess the impact of tVNS. Participants in the study were native English speakers, naïve to tone languages, pseudorandomly assigned to active or control conditions, while balancing for nonlinguistic pitch ability and musical experience. Their performance after tVNS was assessed using a range of more traditional language outcome measures, including accuracy and reaction times from lexical recognition and recall tasks and was triangulated with pupillometry during word-learning to help understand the mechanism through which tVNS operates. Findings are discussed in light of the literatures on lexical tone learning, cognitive effort, and neurostimulation, including specific benefits for learners of tone languages. Recommendations are made for future work on the increasingly popular area of neurostimulation for the field of applied linguistics in the 40th anniversary issue of ARAL.

Difficulty perceiving phonological contrasts in a second language (L2) can impede initial L2 lexical learning. Such is the case for English speakers learning tonal languages, like Mandarin Chinese. Given the hypothesized role of reduced neuroplasticity in adulthood limiting L2 phonological perception, the current study examined whether transcutaneous auricular vagus nerve stimulation (taVNS), a relatively new neuromodulatory technique, can facilitate L2 lexical learning for English speakers learning Mandarin Chinese over 2 days. Using a double-blind design, one group of participants received 10 min of continuous priming taVNS before lexical training and testing each day, a second group received 500 msec of peristimulus (peristim) taVNS preceding each to-be-learned item in the same tasks, and a third group received passive sham stimulation. Results of the lexical recognition test administered at the end of each day revealed evidence of learning for all groups, but a higher likelihood of accuracy across days for the peristim group and a greater improvement in response time between days for the priming group. Analyses of N400 ERP components elicited during the same tasks indicate behavioral advantages for both taVNS groups coincided with stronger lexico-semantic encoding for target words. Comparison of these findings to pupillometry results for the same study reported in Pandža, Phillips, Karuzis, O'Rourke, and Kuchinsky (2020) suggest that positive effects of priming taVNS (but not peristim taVNS) on lexico-semantic encoding are related to sustained attentional effort.

Word frequency has long been viewed as the best predictor of lexical access. However, recent findings have suggested that other corpus-derived metrics (i.e., contextual diversity, semantic diversity) can better explain the word frequency effect in both native speakers and in proficient bilinguals. However, little is known about the contributions of these variables to second language lexical access, where the word frequency effect is purportedly larger than in native speakers. Results from a lexical-decision task with second language learners and a comparison group of native speakers revealed that both contextual diversity and semantic diversity were just as good, if not better, at explaining variance in lexical decision latencies as word frequency. These findings are broadly consistent with that of monolinguals and proficiency bilinguals. The results also underscore the need for more theoretical and empirical focus on different corpus metrics in modelling lexical access. Public Significance StatementHow quickly monolinguals and bilinguals access words from memory has long been thought to be a function of how often we encounter that word (i.e., its frequency), but recent work suggests that monolinguals access words as a function of how often we encounter a word in semantically and contextually distinct environments (i.e., whether a word occurs only in one kind of context or multiple different contexts). This study shows similar effects in bilinguals, which underscores similarities in the mechanisms that influence word recognition in monolinguals and bilinguals. These findings also lend further support to models of language processing that place an emphasis on basic principles of learning and memory in the organization of the mental lexicon.

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