Transcutaneous Auricular Vagus Nerve Stimulation Strengthens Semantic Representations of Foreign Language Tone Words during Initial Stages of Learning.

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 Pandza, N. B., Phillips, I., Karuzis, V. P., O'Rourke, P., and Kuchinsky, S. E. (Neurostimulation and pupillometry: New directions for learning and research in applied linguistics. Annual Review of Applied Linguistics, 40, 56-77, 2020) suggest that positive effects of priming taVNS (but not peristim taVNS) on lexico-semantic encoding are related to sustained attentional effort.

The cognitive underpinnings of mental model construction in L1 and L2.

This study investigates the ability to create mental models and the role of working memory in mental model ability in the first and second language with English-Spanish bilinguals using L1 and L2 versions of the Spatial Integration Task. Participants showed effects of continuity in accuracy in L1 and L2, but only in L1 did they show effects in the reading times. In L1, working memory capacity predicted identification accuracy for discontinuous descriptions in L1, as well as reading time for the critical discontinuous sentence. In L2, accuracy was predicted by L2 reading ability only and there were no significant predictors of reading times. The findings suggest that the lack of availability of working memory resources in L2 induces participants to rely primarily on verbal abilities to create mental models.

Practice makes imperfect: Working memory training can harm recognition memory performance.

There is a great deal of debate concerning the benefits of working memory (WM) training and whether that training can transfer to other tasks. Although a consistent finding is that WM training programs elicit a short-term near-transfer effect (i.e., improvement in WM skills), results are inconsistent when considering persistence of such improvement and far transfer effects. In this study, we compared three groups of participants: a group that received WM training, a group that received training on how to use a mental imagery memory strategy, and a control group that received no training. Although the WM training group improved on the trained task, their posttraining performance on nontrained WM tasks did not differ from that of the other two groups. In addition, although the imagery training group's performance on a recognition memory task increased after training, the WM training group's performance on the task decreased after training. Participants' descriptions of the strategies they used to remember the studied items indicated that WM training may lead people to adopt memory strategies that are less effective for other types of memory tasks. These results indicate that WM training may have unintended consequences for other types of memory performance.

Hemispheric alpha asymmetry and self-rated originality of ideas.

The generation of highly original ideas in divergent thinking tasks has been found to be associated with task-related changes in the alpha band. The goal of the current study was to determine if exposure to brainwave entrainment (BWE) at the alpha centre frequency before and during performance of a divergent thinking task would result in increases in task-related, event-related synchrony and the production of more highly original ideas. We found that alpha entrainment interfered with the oscillatory dynamics associated with divergent thinking such that only the control group showed greater right hemispheric engagement. Furthermore, the control group showed greater self-rated originality. These findings provide confirmation of the importance of hemispheric asymmetry in alpha power to successful divergent thinking and indicate that refinements are required in order for BWE to be used effectively to improve divergent thinking performance.

Semantic access to embedded words? Electrophysiological and behavioral evidence from Spanish and English.

Many multisyllabic words contain shorter words that are not semantic units, like the CAP in HANDICAP and the DURA (hard) in VERDURA (vegetable). The spaces between printed words identify word boundaries, but spurious identification of these embedded words is a potentially greater challenge for spoken language comprehension, a challenge that is handled by different mechanisms in different models of auditory word recognition. Subphonemic acoustic differences--subtle differences in pronunciation--often differentiate embedded words from genuine words. We examined semantic access to embedded words in two languages with different phonology by presenting carrier words followed by targets related to the embedded words and recording event-related potentials and lexical decision times in 34 Spanish/English bilinguals. No evidence of embedded word access was observed in brain activity or behavior, and this could not be attributed to subphonemic acoustic factors. The data place constraints on models of speech segmentation.

Morphological agreement at a distance: dissociation between early and late components of the event-related brain potential.

Syntactic relationships among non-adjacent words are a core aspect of sentence structure. Research on complex sentences with displaced elements has concluded that resolving long-distance dependencies can tax working memory. Here we examine a simpler relationship-morphological agreement between the elements of a noun phrase-across a gradient of distance. Participants read sentences with violations of gender agreement among Spanish nouns, determiners and adjectives. For those explicitly assigned the task of detecting errors, accuracy was uniformly high across the four levels of distance between (dis)agreeing words. A second group performed a comprehension task as ERPs were recorded. Gender agreement errors elicited a left anterior negativity (LAN) regardless of the distance between (dis)agreeing words, indicating that the errors were detected. In contrast, a temporally later component of the ERP (P600) showed decreasing amplitudes as the number of words between (dis)agreeing elements increased. Smaller P600 responses were also associated with slower responses to the comprehension questions. Given other work suggesting that the P600 indexes attempted repair of a problematic sentence structure, the results suggest that the participants became increasingly unwilling to re-visit their initial parse of a sentence as the required effort increased, despite having noted an error. The results are discussed within the context of studies showing that readers often compute inadequate structural representations of sentences. We suggest that P600 amplitude may reflect the costs versus benefits of sentence re-analysis, determined by a combination of sentence structure, task requirements, and the degree to which sentence meaning hinges on a correct structural analysis.