Cross-language Neighborhood Effects in Learners Indicative of an Integrated Lexicon

A predictive coding model of the N400

The N400 event-related component has been widely used to investigate the neural mechanisms underlying real-time language comprehension. However, despite decades of research, there is still no unifying theory that can explain both its temporal dynamics and functional properties. In this work, we show that predictive coding - a biologically plausible algorithm for approximating Bayesian inference - offers a promising framework for characterizing the N400. Using an implemented predictive coding computational model, we demonstrate how the N400 can be formalized as the lexico-semantic prediction error produced as the brain infers meaning from the linguistic form of incoming words. We show that the magnitude of lexico-semantic prediction error mirrors the functional sensitivity of the N400 to various lexical variables, priming, contextual effects, as well as their higher-order interactions. We further show that the dynamics of the predictive coding algorithm provides a natural explanation for the temporal dynamics of the N400, and a biologically plausible link to neural activity. Together, these findings directly situate the N400 within the broader context of predictive coding research. More generally, they raise the possibility that the brain may use the same computational mechanism for inference across linguistic and non-linguistic domains.

Language switching when writing: The role of phonological and orthographic overlap

While language switching of bilinguals has been investigated extensively in the spoken domain, there has been little research on switching while writing. The factors that impact written language switching may differ from those that impact language switching while speaking. Thus, the study's goal was to test to what extent phonological and/or orthographic overlap impacts written language switching. In four experiments (NExp.1 = 34; NExp. 2 = 57; NExp. 3 = 39; NExp. 4 = 39), German-English bilinguals completed a cued language switching task where responses had to be typed. To-be-named translation-equivalent concepts were selected to be similar phonologically, orthographically or neither. Participants switching between languages while writing was facilitated by both phonological and orthographic overlap. Maximum orthographic overlap between translation-equivalent words with dissimilar pronunciations facilitated switching to the extent that no switch costs could be observed. These results imply that overlapping orthography can strongly facilitate written language switching and that orthography's role should be considered more thoroughly in models of bilingual language production.

Eye Movement Measures of Within-Language and Cross-Language Activation During Reading in Monolingual and Bilingual Children and Adults: A Focus on Neighborhood Density Effects

We used eye movement measures of first-language (L1) and second-language (L2) paragraph reading to investigate how the activation of multiple lexical candidates, both within and across languages, influences visual word recognition in four different age and language groups: (1) monolingual children; (2) monolingual young adults; (3) bilingual children; and (4) bilingual young adults. More specifically, we focused on within-language and cross-language orthographic neighborhood density effects, while controlling for the potentially confounding effects of orthographic neighborhood frequency. We found facilitatory within-language orthographic neighborhood density effects (i.e., words were easier to process when they had many vs. few orthographic neighbors, evidenced by shorter fixation durations) across the L1 and L2, with larger effects in children vs. adults (especially the bilingual ones) during L1 reading. Similarly, we found facilitatory cross-language neighborhood density effects across the L1 and L2, with no modulatory influence of age or language group. Taken together, our findings suggest that word recognition benefits from the simultaneous activation of visually similar word forms during naturalistic reading, with some evidence of larger effects in children and particularly those whose words may have differentially lower baseline activation levels and/or weaker links between word-related information due to divided language exposure: bilinguals.

Language control in bimodal bilinguals: Evidence from ERPs

It is currently unclear to what degree language control, which minimizes non-target language interference and increases the probability of selecting target-language words, is similar for sign-speech (bimodal) bilinguals and spoken language (unimodal) bilinguals. To further investigate the nature of language control processes in bimodal bilinguals, we conducted the first event-related potential (ERP) language switching study with hearing American Sign Language (ASL)-English bilinguals. The results showed a pattern that has not been observed in any unimodal language switching study: a switch-related positivity over anterior sites and a switch-related negativity over posterior sites during ASL production in both early and late time windows. No such pattern was found during English production. We interpret these results as evidence that bimodal bilinguals uniquely engage language control at the level of output modalities.

Costs and Benefits of Native Language Similarity for Non-native Word Learning

The present study examined the costs and benefits of native language similarity for non-native vocabulary learning. Because learning a second language (L2) is difficult, many learners start with easy words that look like their native language (L1) to jumpstart their vocabulary. However, this approach may not be the most effective strategy in the long-term, compared to introducing difficult L2 vocabulary early on. We examined how L1 orthographic typicality affects pattern learning of novel vocabulary by teaching English monolinguals either Englishlike or Non-Englishlike pseudowords that contained repeated orthographic patterns. We found that overall, the first words that individuals learned during initial acquisition influenced which words they acquired later. Specifically, learning a new word in one session made it easier to acquire an orthographically similar word in the next session. Similarity among non-native words interacted with native language similarity, so that words that looked more like English were easier to learn at first, but they were less effective at influencing later word learning. This demonstrates that although native language similarity has a beneficial effect early on, it may reduce learners' ability to benefit from non-native word patterns during continued acquisition. This surprising finding demonstrates that making learning easier may not be the most effective long-term strategy. Learning difficult vocabulary teaches the learner what makes non-native words unique, and this general wordform knowledge may be more valuable than the words themselves. We conclude that native language similarity modulates new vocabulary acquisition and that difficulties during learning are not always to be avoided, as additional effort early on can pay later dividends.

Orthographic neighborhood density modulates the size of transposed-letter priming effects

We used transposed-letter (TL) priming to test the lexical tuning hypothesis, which states that words from high-density orthographic neighborhoods have more precise orthographic codes than words from low-density neighborhoods. Replicating standard TL priming effects, target words elicited faster lexical decision responses and smaller amplitude N250s and N400s when preceded by TL primes (e.g., leomn-LEMON) compared with substitution primes (e.g., leuzn-LEMON) overall. We expected that if high-density words have more precise orthographic representations (i.e., with each letter assigned to a specific position), then they should be relatively less activated by TL primes and should give rise to smaller TL priming effects. In line with our prediction, N250 (but not N400 or behavioral) TL priming was significantly smaller for high-density words compared with low-density words over posterior sites. Such an interaction was not observed for pseudoword targets. Consistent with the lexical tuning hypothesis then, this pattern suggests that the nature of the orthographic code used to access lexical representations differs depending on the number of neighboring words in the lexicon. We conclude by discussing how lexical tuning could be implemented in current models of orthographic processing.

Integration of newly learned L2 words into the mental lexicon is modulated by vocabulary learning method

The aim of the study was to investigate both L2 word integration and the effect of learning method on it. For this purpose, an L2 word-learning paradigm was designed with two learning methods: L2 words were paired with videos in the first one and their translation-equivalent L1 words in the second. To test L2 word integration, a lexical decision task associated with form priming was administered before and after the learning phase. The L2 words to be learned were used as primes. Forty-eight participants participated in the study. Before learning, a facilitation effect was obtained with pseudowords (not already learned L2 words) as primes and L1 words as targets. After learning, L2 words no longer facilitated L1 word recognition when learned with the video method, while they still had this effect when learned with the L1 words - L2 words method. In accordance with the prime lexicality effect (PLE), this absence of a facilitation effect indicates that L1 words and L2 words are involved in a lexical competition process common to the two languages. This result highlights swift lexicalisation and demonstrates the effect of learning method in lexicalisation.

The role of phonology during visual word learning in adults: An integrative review

Throughout their lifetime, adults learn new words in their native lannguage, and potentially also in a second language. However, they do so with variable levels of success. In the auditory word learning literature, some of this variability has been attributed to phonological skills, including decoding and phonological short-term memory. Here I examine how the relationship between phonological skills and word learning applies to the visual modality. I define the availability of phonology in terms of (1) the extent to which it is biased by the learning environment, (2) the characteristics of the words to be learned, and (3) individual differences in phonological skills. Across these three areas of research, visual word learning improves when phonology is made more available to adult learners, suggesting that phonology can facilitate learning across modalities. However, the facilitation is largely specific to alphabetic languages, which have predictable sublexical correspondences between orthography and phonology. Therefore, I propose that phonology bootstraps visual word learning by providing a secondary code that constrains and refines developing orthographic representations.

What about proactive language control?

While several reviews provide an in-depth discussion on reactive language control, which is the language control process that is initiated when the non-target language disrupts the selection of target language words, few have touched on proactive language control, which is the language control process implemented as an anticipation of any non-target language interference disrupting the selection of target language words. In the current review, three prominent markers of proactive language control are discussed (i.e., the reversed language dominance effect, language-mixing costs, and the blocked language-order effect). Based on these three markers, it appears that proactive language control can be implemented to mainly restrict interference from the first language during bilingual language production, but is typically absent during bilingual language comprehension. The literature also implies that proactive language control might be partly domain general. With respect to the underlying mechanism of proactive language control, there are some indications that proactive language control relies on inhibition, but no unequivocal evidence has been provided so far.

The Role of Orthotactics in Language Switching: An ERP Investigation Using Masked Language Priming

It is commonly accepted that bilinguals access lexical representations from their two languages during language comprehension, even when they operate in a single language context. Language detection mechanisms are, thus, hypothesized to operate after the stage of lexical access during visual word recognition. However, recent studies showed reduced cross-language activation when sub-lexical properties of words are specific to one of the bilingual's two languages, hinting at the fact that language selection may start before the stage of lexical access. Here, we tested highly fluent Spanish-Basque and Spanish-English bilinguals in a masked language priming paradigm in which first language (L1) target words are primed by unconsciously perceived L1 or second language (L2) words. Critically, L2 primes were either orthotactically legal or illegal in L1. Results showed automatic language detection effects only for orthotactically marked L2 primes and within the timeframe of the N250, an index of sub-lexical-to-lexical integration. Marked L2 primes also affected the processing of L1 targets at the stage of conceptual processing, but only in bilinguals whose languages are transparent. We conclude that automatic and unconscious language detection mechanisms can operate at sub-lexical levels of processing. In the absence of sub-lexical language cues, unconsciously perceived primes in the irrelevant language might not automatically trigger post-lexical language identification, thereby resulting in the lack of observable language switching effects.

Task modulates ERP effects of orthographic neighborhood for pseudowords but not words

Words and pseudowords from high-density orthographic neighborhoods elicit larger amplitude N400s than similar items from low-density orthographic neighborhoods in the lexical decision task. This pattern could be interpreted as an increase in the amount of lexico-semantic information to be processed or as an increase in difficulty identifying a word (or rejecting a pseudoword) amongst many co-activated alternatives. In order to dissociate between these mechanisms, we compared neighborhood effects between a lexical decision task (LDT) and a letter search task (LST). Behaviorally, we found the standard neighborhood and lexicality effects in the LDT, but no significant effects in the LST. Thus, behavioral responses were sensitive to the decisions required by the respective tasks. Electrophysiologically, we found similar N400 neighborhood effects between tasks for words, but the N400 neighborhood effect for pseudowords was only present in the LDT. Moreover, the effect of neighborhood in the LDT occurred earlier for words than for pseudowords. These nuanced differences in the time course and automaticity of word and pseudoword neighborhood effects lend insight into the processes that underlie N400 effects of orthographic neighborhood and how they unfold over time. We propose that the early neighborhood effects for words across tasks were driven by highly automatized word identification processes that were sensitive to the lateral inhibition generated by orthographic neighbors. In contrast, the later neighborhood effects for pseudowords in the LDT could have been driven by task-specific processes tied to how global lexical activity is used to make a lexical decision.

An ERP Investigation of L2–L1 Translation Priming in Adult Learners

A longstanding debate centers around how beginning adult bilinguals process words in their second language (L2). Do they access the meaning of the L2 words directly or do they first activate the native language (L1) translation equivalents in order to access meaning? To address this question, we used ERPs to investigate how newly learned L2 words influence processing of their L1 translation equivalents. We taught participants the meanings of 80 novel L2 (pseudo)words by presenting them with pictures of familiar objects. After 3 days of learning, participants were tested in a backward translation priming paradigm with a short (140 ms) stimulus onset asynchrony. L1 targets preceded by their L2 translations elicited faster responses and smaller amplitude negativities than the same L1 targets preceded by unrelated L2 words. The bulk of the ERP translation priming effect occurred within the N400 window (350–550 ms), suggesting that the new L2 words were automatically activating their semantic representations. A weaker priming effect in the preceding window (200–350 ms) was found at anterior sites, providing some evidence that the forms of the L1 translation equivalents had also been activated. These results have implications for models of L2 processing at the earliest stages of learning.

From sublexical facilitation to lexical competition: ERP effects of masked neighbor priming

Interactive-activation models posit that visual word recognition involves co-activation of orthographic neighbors (e.g., note, node) and competition among them via lateral inhibitory connections. Behavioral evidence of this lexical competition comes from masked priming paradigms, in which target words elicit slower responses when preceded by a neighbor (e.g., note-NODE) than when preceded by an unrelated word (e.g., kiss-NODE). In the present study, we used ERPs to investigate how masked high frequency word primes influence processing of low frequency word and pseudoword targets. Word targets preceded by a neighbor prime elicited larger negativities within the N400 window than those preceded by an unrelated prime across bilateral anterior sites, which we call a reversed N400 priming effect. Consistent with the behavioral literature, the size of the reversed N400 priming effect was larger for targets from high-density orthographic neighborhoods and for participants who scored higher on a behavioral measure of spelling recognition. Indeed, the opposite effect (i.e., smaller negativities within the N400 window for word targets preceded by a neighbor) was observed for words from low-density orthographic neighborhoods and for less-skilled spellers. Traditional priming was also observed within the N250 window for word targets and within both the N250 or N400 windows for pseudoword targets. The specificity of the reversed N400 priming effect to situations in which both words have precise lexical representations suggests that it, like the behavioral interference effect, indexes lexical competition during visual word recognition.