Improvement of memory-based reading recall using transcutaneous auricular vagus nerve stimulation

Expert reading acquisition is marked by fluent, effortless decoding and adequate comprehension skills and is required for modern daily life. In spite of its importance, many individuals struggle with reading comprehension even when decoding skills are adequate. Unfortunately, effective reading comprehension interventions are limited, especially for adults. A growing body of research suggests that non-invasive transcutaneous stimulation of the auricular vagus nerve (taVNS) may drive neural plasticity for low-level reading skills such as speech sound perception and letter-sound learning, but it is unknown whether taVNS can improve higher level skills as well. Thus, the current study was designed to evaluate whether taVNS paired with passage reading can improve reading comprehension performance. Twenty-four typically developing young adults were recruited and screened for baseline reading and working memory skills. Participants received either sham or active taVNS while reading short passages out loud. Immediately following each passage, participants answered a series of test questions that required either direct recall of passage details or more complete comprehension of the passage content. While taVNS did not improve the mechanics of reading (e.g., reading rate or accuracy), there was a significant benefit of active taVNS on test questions. This effect was driven by significant improvement on accuracy for memory questions while there was no effect of taVNS on comprehension question accuracy. These findings suggest that taVNS may be beneficial for enhancing memory, but its efficacy may be limited in higher cognitive domains.

Matching the Mismatch: The interaction between perceptual and conceptual cues in bilinguals’ speech perception

Speech perception involves both conceptual cues and perceptual cues. These, individually, have been shown to guide bilinguals’ speech perception; but their potential interaction has been ignored. Explicitly, bilinguals have been given perceptual cues that could be predicted by the conceptual cues. Therefore, to target the perceptual-conceptual interaction, we created a restricted range of perceptual cues that either matched, or mismatched, bilinguals’ conceptual predictions based on the language context. Specifically, we designed an active speech perception task that concurrently collected electrophysiological data from Spanish–English bilinguals and English monolinguals to address the extent to which this cue interaction uniquely affects bilinguals’ speech sound perception and allocation of attentional resources. Bilinguals’ larger MMN-N2b in the mismatched context aligns with the Predictive Coding Hypothesis to suggest that bilinguals use their diverse perceptual routines to best allocate cognitive resources to perceive speech.

Motoric Training Alters Speech Sound Perception and Production — Active Listening Training Does Not Lead into Learning Outcomes

Accurate speech-sound perception and production are prerequisites for communication in a non-native language. Earlier research has shown that new categorization and pronunciation patterns evolve in different learning settings and that these skills can be trained with various methods. We tested the effects of two types of training protocols on the production and identification of L2 vowels embedded in a pseudo-word context. Group 1 (Producers) participated in a listen and repeat training, where they produced the target stimulus /tᵾ:ti/ and the non-target stimulus /ty:ti/ after the example in a pseudo-randomized order; Group 2 (Listeners) was instructed to count the number of targets /tᵾ:ti/ in the same stimulus train without any motoric production movements. The results showed clearly that listen and repeat training led to plastic changes both in production and in identification, while no learning effects were obtained with the listening paradigm. This suggests a significant role of motoric experience in the acquisition of speech.

Perception of height and categorization of Brazilian Portuguese front vowels

ABSTRACT Cross-linguistic typological observations and theoretical models in phonology suggest that certain speech sound distinctions are more complex then others. One such example is the opposition between mid-high and mid-low vowels, usually thought to be more complex than the opposition between high and mid vowels. The present study provides experimental evidence on speech sound perception which supports this notion. Native Brazilian Portuguese speakers performed vowel classification tasks involving either the distinction between the front high mid /e/ and the front high /i/, or the distinction between the front high mid /e/ and the front low mid /ε/ vowel. Measures of response time and discriminability (d') at the vowel category boundaries were obtained. Participants showed significantly slower responses and lower d' values in the "e-ε" as compared to the "i-e" classification task. Results indicate that perceptually distinguishing /e/ from /ı/ requires more processing time and resources, and involves more complex information than distinguishing /e/ from /i/.