The ERP signature of the contextual diversity effect in visual word recognition

Tracking the brain signature of (mis)spelled logotypes via letter transpositions and replacements

All leading models of visual word recognition assume a hierarchical process that progressively converts the visual input into abstract letter and word representations. However, the results from recent behavioral studies suggest that the mental representations of words with a highly consistent visual format, such as logotypes, may comprise not only purely abstract information but also perceptual information. This hypothesis would explain why participants often misperceive transposed-letter misspellings with the original base words to a larger degree in logotypes (e.g., SASMUNG, but not SARVUNG, is perceived as SAMSUNG) than in common words. The present experiment examined the electrophysiological signature behind the identification of correctly spelled and misspelled logotypes (via letter transposition or replacement) in an ERP go/no-go semantic categorization experiment. Results showed that N400 amplitudes for transposed-letter misspelled logotypes (SASMUNG) and intact logotypes (SAMSUNG) did not differ significantly across various time windows (until 600 ms), whereas replacement-letter misspelled logotypes (SARVUNG) yielded consistently larger N400 amplitudes. These findings reveal that the mental representations of logotypes are particularly resistant to minor orthographic changes, which has important theoretical and applied (e.g., marketing) implications.

Event-related brain potentials in lexical processing with Chinese characters show effects of contextual diversity but not word frequency

The diversity of contexts in which a word occurs, operationalized as CD, is strongly correlated with response times in visual word recognition, with higher CD words being recognized faster. CD and token word frequency (WF) are highly correlated but in behavioral studies when other variables that affect word visual recognition are controlled for, the WF effect is eliminated when contextual diversity (CD) is controlled. In contrast, the only event-related potential (ERP) study to examine CD and WF Vergara-Martínez et al., Cognitive, Affective, & Behavioral Neuroscience, 17, 461-474, (2017) found effects of both WF and CD with different distributions in the 225- to 325-ms time window. We conducted an ERP study with Chinese characters to explore the neurocognitive dynamics of WF and CD. We compared three groups of characters: (1) characters high in frequency and low in CD; (2) characters low in frequency and low in CD; and (3) characters high in frequency and high in CD. Behavioral data showed significant effects of CD but not WF. Character CD, but not character frequency, modulated the late positive component (LPC): high-CD characters elicited a larger LPC, widely distributed, with largest amplitude at the posterior sites compared to low-CD characters in the 400-to 600-ms time window, consistent with earlier ERP studies of WF in Chinese, and with the hypothesis that CD affects semantic and context-based processes. No WF effect on any ERP components was observed when CD was controlled. The results are consistent with behavioral results showing CD but not WF effects, and in particular with a "context constructionist" framework.

Event-related Potential Measures of Visual Word Processing in Monolingual and Bilingual Children and Adults: A Focus on Word Frequency Effects

How does language background influence the neural correlates of visual word recognition in children? To address this question, we used an ERP lexical decision task to examine first-language (L1) and second-language (L2) visual word processing in monolingual and bilingual school-aged children and young adults (n = 123). In particular, we focused on the effects of word frequency (an index of lexical accessibility) on RTs and the N400 ERP component. Behaviorally, we found larger L1 versus L2 word frequency effects among bilingual children, driven by faster and more accurate responses to higher-frequency words (no other language or age group differences were observed). Neurophysiologically, we found larger L1 word frequency effects in bilinguals versus monolinguals (across both age groups), reflected in more negative ERP amplitudes to lower-frequency words. However, the bilingual groups processed L1 and L2 words similarly, despite lower levels of subjective and objective L2 proficiency. Taken together, our findings suggest that divided L1 experience (but not L2 experience) influences the neural correlates of visual word recognition across childhood and adulthood.

SUBTLEX-CY: A new word frequency database for Welsh

We present SUBTLEX-CY, a new word frequency database created from a 32-million-word corpus of Welsh television subtitles. An experiment comprising a lexical decision task examined SUBTLEX-CY frequency estimates against words with inconsistent frequencies in a much smaller Welsh corpus that is often used by researchers, the Cronfa Electroneg o'r Gymraeg (CEG), and three other Welsh word frequency databases. Words were selected that were classified as low frequency (LF) in SUBTLEX-CY and high frequency (HF) in CEG and compared with words that were classified as medium frequency (MF) in both SUBTLEX-CY and CEG. Reaction time analyses showed that HF words in CEG were responded to more slowly compared to MF words, suggesting that SUBTLEX-CY corpus provides a more reliable estimate of Welsh word frequencies. The new Welsh word frequency database that also includes part-of-speech, contextual diversity, and other lexical information is freely available for research purposes on the Open Science Framework repository at https://osf.io/9gkqm/.

Effect of contextual diversity on word recognition in different semantic contexts

Efficient word recognition is important to facilitate reading comprehension. Two important factors influence word recognition-word frequency (WF) and contextual diversity (CD)-but studies have not reached consistent conclusions on their role. Based on previous studies, the present study strictly controlled the anticipation of sentence context on target words. In the context of the semantic incongruence of Chinese sentences-that is, when the context is equivalent and low in anticipation of the target noun-CD effects were found on late processing indicators of the eye movement data of parafoveal words, and the CD feature of parafoveal words led to a significant parafoveal-on-foveal effect. However, none of these results were found in the semantically reasonable (semantic congruence) context. The results suggested that high CD words are better at adapting to unexposed or learned contexts, which was not the case for high WF words.

Contextual dynamics in lexical encoding across the ageing spectrum: A simulation study

The field of psycholinguistics has recently questioned the primacy of word frequency (WF) in influencing word recognition and production, instead focusing on the importance of a word's contextual diversity (CD). WF is operationalised by counting the number of occurrences of a word in a corpus, while a word's CD is a count of the number of contexts that a word occurs in, with repetitions within a context being ignored. Numerous studies have converged on the conclusion that CD is a better predictor of word recognition latency and accuracy than frequency. These findings support a cognitive mechanism based on the principle of likely need over the principle of repetition in lexical organisation. In the current study, we trained the semantic distinctiveness model on communication patterns in social media platforms consisting of over 55-billion-word tokens and examined the ability of theoretically distinct models to explain word recognition latency and accuracy data from over 1 million participants from the Mandera et al. English Crowdsourding Project norms, consisting of approximately 59,000 words across six age bands ranging from ages 10 to 60 years. There was a clear quantitative trend across the age bands, where there is a shift from a social environment-based attention mechanism in the "younger" models, to a clear dominance for a discourse-based attention mechanism as models "aged." This pattern suggests that there is a dynamical interaction between the cognitive mechanisms of lexical organisation and environmental information that emerges across ageing.

Environment Context Variability and Incidental Word Learning: A Virtual Reality Study

Previous research has shown that changes in the scenarios in which something is learned and recalled, respectively, may result in a subpar performance in memory recollection. The current study aimed to evaluate how changes in the visuo-perceptual environmental learning context impact incidental vocabulary learning. To this end, a highly immersive virtual reality setting was created, and participants were required to read eight distinct stories visually presented to them. A novel word was delivered twice in every paragraph and embedded in each story. Stories could be displayed either in a high variability condition, where each paragraph was shown in a new environment context (four different classrooms) or in a low variability condition, where each paragraph was shown in the same context. The findings obtained across four assessment tasks (free recall, recognition, picture matching, and sentence completion) demonstrated that significant visuo-perceptual variability did not bring about any disadvantages in word learning. Thus, perceptual information from a physically diverse environment could provide a variety of instructional and educational beneficial possibilities in the absence of a learning disadvantage.

Diversity matters: The sensitivity to sublexical orthographic regularities increases with contextual diversity

Readers capture statistics about letter co-occurrences very rapidly. This has been demonstrated with artificial lexicons and/or with restricted sets of orthographic regularities. The aim of the study was twofold: To examine the learning of new orthographic regularities in a more incidental exposure paradigm, and to investigate the impact of the diversity of letter contexts in which new orthographic regularities appear. For 2 months, participants played detection games for 20 min per day and were exposed to a large set of pseudowords, some of which included new bigrams (e.g., GK). Half of the new bigrams occurred in eight different items (high contextual diversity) and the other half were presented in only two items (low context diversity). At six time points, the participants performed a "wordlikeness" task in which they chose between two new pseudowords the one that was more similar to the items previously exposed (e.g., PUGKALE vs. PUGZALE). The results showed that the participants very rapidly developed a preference for items with a frequent new bigram and that this sensitivity increased steadily over the 2 months. Furthermore, the sensitivity to these new orthographic regularities was higher in cases of high letter contextual diversity. The latter result parallels what is observed at a lexical level with semantic contextual diversity.

Does narrator variability facilitate incidental word learning in the classroom?

Recent studies have revealed that presenting novel words across various contexts (i.e., contextual diversity) helps to consolidate the meaning of these words both in adults and children. This effect has been typically explained in terms of semantic distinctiveness (e.g., Semantic Distinctiveness Model, Jones et al., Canadian Journal of Experimental Psychology, 66(2), 115, 2012). However, the relative influence of other, non-semantic, elements of the context is still unclear. In this study, we examined whether incidental learning of new words in children was facilitated when the words were uttered by several individuals rather than when they were uttered by the same individual. In the learning phase, the to-be-learned words were presented through audible fables recorded either by the same voice (low diversity) or by different voices (high diversity). Subsequently, word learning was assessed through two orthographic and semantic integration tasks. Results showed that words uttered by different voices were learned better than those uttered by the same voice. Thus, the benefits of contextual diversity in word learning extend beyond semantic differences among contexts; they also benefit from perceptual differences among contexts.

The effects of contextual diversity on incidental vocabulary learning in the native and a foreign language

Vocabulary learning occurs throughout the lifespan, often implicitly. For foreign language learners, this is particularly challenging as they must acquire a large number of new words with little exposure. In the present study, we explore the effects of contextual diversity—namely, the number of texts a word appears in—on native and foreign language word learning. Participants read several texts that had novel pseudowords replacing high-frequency words. The total number of encounters with the novel words was held constant, but they appeared in 1, 2, 4, or 8 texts. In addition, some participants read the texts in Spanish (their native language) and others in English (their foreign language). We found that increasing contextual diversity improved recall and recognition of the word, as well as the ability to match the word with its meaning while keeping comprehension unimpaired. Using a foreign language only affected performance in the matching task, where participants had to quickly identify the meaning of the word. Results are discussed in the greater context of the word learning and foreign language literature as well as their importance as a teaching tool.

SUBTLEX-CAT: Subtitle word frequencies and contextual diversity for Catalan

SUBTLEX-CAT is a word frequency and contextual diversity database for Catalan, obtained from a 278-million-word corpus based on subtitles supplied from broadcast Catalan television. Like all previous SUBTLEX corpora, it comprises subtitles from films and TV series. In addition, it includes a wider range of TV shows (e.g., news, documentaries, debates, and talk shows) than has been included in most previous databases. Frequency metrics were obtained for the whole corpus, on the one hand, and only for films and fiction TV series, on the other. Two lexical decision experiments revealed that the subtitle-based metrics outperformed the previously available frequency estimates, computed from either written texts or texts from the Internet. Furthermore, the metrics obtained from the whole corpus were better predictors than the ones obtained from films and fiction TV series alone. In both experiments, the best predictor of response times and accuracy was contextual diversity.

The role of experience for abstract concepts: Expertise modulates the electrophysiological correlates of mathematical word processing

Embodied theories assign experience a crucial role in shaping conceptual representations. Supporting evidence comes mostly from studies on concrete concepts, where e.g., motor expertise facilitated action concept processing. This study examined experience-dependent effects on abstract concept processing. We asked participants with high and low mathematical expertise to perform a lexical decision task on mathematical and nonmathematical abstract words, while acquiring event-related potentials. Analyses revealed an interaction of expertise and word type on the amplitude of a fronto-central N400 and a centro-parietal late positive component (LPC). For mathematical words, we found a trend for a lower N400 and a significantly higher LPC amplitude in experts compared to nonexperts. No differences between groups were found for nonmathematical words. The results suggest that expertise affects the processing stages of semantic integration and memory retrieval specifically for expertise-related concepts. This study supports the generalization of experience-dependent conceptual processing mechanisms to the abstract domain.

Lexical category acquisition is facilitated by uncertainty in distributional co-occurrences

This paper analyzes distributional properties that facilitate the categorization of words into lexical categories. First, word-context co-occurrence counts were collected using corpora of transcribed English child-directed speech. Then, an unsupervised k-nearest neighbor algorithm was used to categorize words into lexical categories. The categorization outcome was regressed over three main distributional predictors computed for each word, including frequency, contextual diversity, and average conditional probability given all the co-occurring contexts. Results show that both contextual diversity and frequency have a positive effect while the average conditional probability has a negative effect. This indicates that words are easier to categorize in the face of uncertainty: categorization works best for words which are frequent, diverse, and hard to predict given the co-occurring contexts. This shows how, in order for the learner to see an opportunity to form a category, there needs to be a certain degree of uncertainty in the co-occurrence pattern.

Early use of phonological codes in deaf readers: An ERP study

Previous studies suggest that deaf readers use phonological information of words when it is explicitly demanded by the task itself. However, whether phonological encoding is automatic remains controversial. The present experiment examined whether adult congenitally deaf readers show evidence of automatic use of phonological information during visual word recognition. In an ERP masked priming lexical decision experiment, deaf participants responded to target words preceded by a pseudohomophone (koral - CORAL) or an orthographic control prime (toral - CORAL). Responses were faster for the pseudohomophone than for the orthographic control condition. The N250 and N400 amplitudes were reduced for the pseudohomophone when compared to the orthographic control condition. Furthermore, the magnitude of both the behavioral and the ERP pseudohomophone effects in deaf readers was similar to that of a group of well-matched hearing controls. These findings reveal that phonological encoding is available to deaf readers from the early stages of visual word recognition. Finally, the pattern of correlations of phonological priming with reading ability suggested that the amount of sub-lexical use of phonological information could be a main contributor to reading ability for hearing but not for deaf readers.

Contextual diversity facilitates learning new words in the classroom

In the field of word recognition and reading, it is commonly assumed that frequently repeated words create more accessible memory traces than infrequently repeated words, thus capturing the word-frequency effect. Nevertheless, recent research has shown that a seemingly related factor, contextual diversity (defined as the number of different contexts [e.g., films] in which a word appears), is a better predictor than word-frequency in word recognition and sentence reading experiments. Recent research has shown that contextual diversity plays an important role when learning new words in a laboratory setting with adult readers. In the current experiment, we directly manipulated contextual diversity in a very ecological scenario: at school, when Grade 3 children were learning words in the classroom. The new words appeared in different contexts/topics (high-contextual diversity) or only in one of them (low-contextual diversity). Results showed that words encountered in different contexts were learned and remembered more effectively than those presented in redundant contexts. We discuss the practical (educational [e.g., curriculum design]) and theoretical (models of word recognition) implications of these findings.

The effect of character contextual diversity on eye movements in Chinese sentence reading

Chen, Huang, et al. (Psychonomic Bulletin & Review, 2017) found that when reading two-character Chinese words embedded in sentence contexts, contextual diversity (CD), a measure of the proportion of texts in which a word appears, affected fixation times to words. When CD is controlled, however, frequency did not affect reading times. Two experiments used the same experimental designs to examine whether there are frequency effects of the first character of two-character words when CD is controlled. In Experiment 1, yoked triples of characters from a control group, a group matched for character CD that is lower in frequency, and a group matched in frequency with the control group, but higher in character CD, were rotated through the same sentence frame. In Experiment 2 each character from a larger set was embedded in a separate sentence frame, allowing for a larger difference in log frequency compared to Experiment 1 (0.8 and 0.4, respectively). In both experiments, early and later eye movement measures were significantly shorter for characters with higher CD than for characters with lower CD, with no effects of character frequency. These results place constraints on models of visual word recognition and suggest ways in which Chinese can be used to tease apart the nature of context effects in word recognition and language processing in general.