Word learning: An ERP investigation of word experience effects on recognition and word processing

Learning new words by reading books: Does semantic information help?

Encountering new words during reading is a common experience of any adult reader and it constitutes an important source of word knowledge. Despite the ubiquity of this phenomenon, studies remain scarce in adults. Here, we addressed new word acquisition in adults using a natural contextual exposure, and we focused on the influence of context informativeness on orthographic learning. Indeed, previous studies suggest that the availability of semantic information plays an important role in orthographic learning in adults, but no such advantage was found in children. We hypothesised that this discrepancy comes from the fact that new word learning was examined almost only through artificial settings in adults. On the contrary, in the present study, adult participants were exposed to new words by reading a book. Half of the new words were embedded in informative contexts (easy to infer new word meaning) and the other half in less informative contexts. Both recall and recognition tasks were used to assess orthographic and semantic learning. The results showed efficient learning of the orthographic form and no reliable effect of the context informativeness. Regarding semantic learning, we found that if a word was correctly spelled, its definition was more likely to be retrieved. This shows that the orthographic and semantic dimensions of a word co-occurring in context are likely to influence each other during lexical acquisition. More generally, the present experiment showed that using an ecological learning design is essential to understand the mechanism of new word learning.

Learning to Spell Novel Words: The Relationship Between Orthographic and Semantic Representations During Incidental Learning

The current study investigated whether semantic (meaning) knowledge benefits learning orthography (spelling). Adult readers read 14 novel non-words embedded in sentences with informative or uninformative context. Orthographic and semantic posttests assessed learning. In E1, results indicated that the relationship between context and orthographic accuracy was moderated by spelling frequency. In E2, all novel words had low-frequency spelling bodies. The results did not show a main effect of access to meaning on learning spelling, but they did reveal a strong association between learning spelling and meaning. In E3, participants received fewer exposures to increase the task difficulty. There was no main effect of access to words' meaning on learning spellings, but there were strong associations between orthographic and semantic posttest accuracy. These findings indicate that teaching words' spellings and meanings independently of one another may not be the most beneficial means of learning new words.

Modeling developmental changes in print tuning in a transparent alphabetic orthography

The development of print tuning involves the increased specificity and redundancy for orthographic representations. However, it is by no means clear how decoding accuracy and efficiency are related over the years and how it affects reading disability. In the present study, we monitored the development of accuracy and efficiency of decoding in Dutch as a relatively transparent orthography as a function of orthographic complexity and lexical status throughout the primary grades. There was clear evidence that development of decoding accuracy preceded development of decoding efficiency and that a certain threshold of accuracy is needed for decoding efficiency to evolve. Furthermore, it was shown that pseudoword decoding efficiency predicted growth in word decoding efficiency, especially for the higher levels of orthographic complexity. There was also evidence that accuracy precedes efficiency across different profiles of readers and that decoding strength can be defined as a function of orthographic complexity and lexicality.

What makes somatosensory short-term memory maintenance effective? An EEG study comparing contralateral delay activity between sighted participants and participants who are blind

Somatosensory short-term memory is essential for object recognition, sensorimotor learning, and, especially, Braille reading for people who are blind. This study examined how visual sensory deprivation and a compensatory focus on somatosensory information influences memory processes in this domain. We measured slow cortical negativity developing during short-term tactile memory maintenance (tactile contralateral delay activity, tCDA) in frontal and somatosensory areas while a sample of 24 sighted participants and 22 participants who are blind completed a tactile change-detection task where varying loads of Braille pin patterns served as stimuli. Auditory cues, appearing at varying latencies between sample arrays, could be used to reduce memory demands during maintenance. Participants who are blind (trained Braille readers) outperformed sighted participants behaviorally. In addition, while task-related frontal activation featured in both groups, participants who are blind uniquely showed higher tCDA amplitudes specifically over somatosensory areas. The site specificity of this component's functional relevance in short-term memory maintenance was further supported by somatosensory tCDA amplitudes first correlating across the whole sample with behavioral performance, and secondly showing sensitivity to varying memory load. The results substantiate sensory recruitment models and provide new insights into the effects of visual sensory deprivation on tactile processing. Between-group differences in the interplay between frontal and somatosensory areas during somatosensory maintenance also suggest that efficient maintenance of complex tactile stimuli in short-term memory is primarily facilitated by lateralized activity in somatosensory cortex.

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 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.

Neurophysiological Correlates of Top-Down Phonological and Semantic Influence during the Orthographic Processing of Novel Visual Word-Forms

The acquisition of new vocabulary is usually mediated by previous experience with language. In the visual domain, the representation of orthographically unfamiliar words at the phonological or conceptual levels may facilitate their orthographic learning. The neural correlates of this advantage were investigated by recording EEG activity during reading novel and familiar words across three different experiments (n = 22 each), manipulating the availability of previous knowledge on the novel written words. A different pattern of event-related potential (ERP) responses was found depending on the previous training, resembling cross-level top-down interactive effects during vocabulary acquisition. Thus, whereas previous phonological experience caused a modulation at the post-lexical stages of the visual recognition of novel written words (~520 ms), additional semantic training influenced their processing at a lexico-semantic stage (~320 ms). Moreover, early lexical differences (~180 ms) elicited in the absence of previous training did not emerge after both phonological and semantic training, reflecting similar orthographic processing and word-form access.

From Psychoacoustics to Brain Waves: A Longitudinal Approach to Novel Word Learning

Musical expertise has been shown to positively influence high-level speech abilities such as novel word learning. This study addresses the question whether low-level enhanced perceptual skills causally drives successful novel word learning. We used a longitudinal approach with psychoacoustic procedures to train 2 groups of nonmusicians either on pitch discrimination or on intensity discrimination, using harmonic complex sounds. After short (approximately 3 hr) psychoacoustic training, discrimination thresholds were lower on the specific feature (pitch or intensity) that was trained. Moreover, compared to the intensity group, participants trained on pitch were faster to categorize words varying in pitch. Finally, although the N400 components in both the word learning phase and in the semantic task were larger in the pitch group than in the intensity group, no between-group differences were found at the behavioral level in the semantic task. Thus, these results provide mixed evidence that enhanced perception of relevant features through a few hours of acoustic training with harmonic sounds causally impacts the categorization of speech sounds as well as novel word learning. These results are discussed within the framework of near and far transfer effects from music training to speech processing.

The Effect of Semantic Similarity on Learning Ambiguous Words in a Second Language: An Event-Related Potential Study

Ambiguous words have multiple meanings. How these multiple meanings interact with each other during ambiguous word learning remains unclear. The current study adopted an event-related potentials (ERPs) technique to explore whether there is an interaction between two meanings when learning second language (L2) ambiguous words and how semantic similarity affects ambiguous word learning. In order to explore this issue, Chinese-English bilinguals were asked to learn pseudowords, which were paired with either two related new meanings (polysemes), two unrelated new meanings (homonyms), or one single new meaning (monosomies) over 2 consecutive days. ERP results revealed that learning the second meaning of a homonym induced a more negative N400 than the first meaning; learning the second meaning of a polyseme tended to produce a more positive late component (LPC) than the first meaning. These results indicate that the first meaning of homonyms may interfere with learning their second meaning. However, the first meaning of polysemous words may facilitate learning their second meaning. The current findings suggest that different mechanisms might be involved in learning L2 homonyms and polysemes.

Investigating Implicit and Explicit Word Learning in School-age Children Using a Combined Behavioral-Event Related Potential (ERP) Approach

One challenge in word learning research is how to operationalize learning. We combined behavioral measures with EEG to examine implicit and explicit recognition of words previously introduced with or without meaning in an incidental learning task. Participants (8-11-year-old children) were not able to recognize previously introduced nonsense words and better performance on the learning task resulted in poorer word recognition. The N400 amplitude differed between nonsense words with meaning versus nonsense words no meaning and novel nonsense words. Results indicate that introducing a nonsense word with meaning does not aid in explicit word learning but improves implicit word learning.

No interaction between rivastigmine and citalopram on memory and novelty processing in healthy human volunteers

BACKGROUND

Animal literature suggests an interaction between acetylcholine and serotonin on cognitive functions.

AIMS

The aim of the current study was to assess whether both neurotransmitters interact during memory and novelty processing in humans.

METHODS

We tested the interaction between acetylcholine and serotonin on cognitive functions in healthy volunteers by means of treatment with rivastigmine and citalopram, respectively.

RESULTS

The main result of the study showed that during the verbal learning task participants significantly recalled fewer words after citalopram treatment than after rivastigmine or placebo during both the immediate and delayed recall tasks. Rivastigmine was not able to reverse the impairing effect of citalopram.

CONCLUSIONS

This finding is in line with previous studies in which we manipulated acetylcholine and serotonin in different manners. Taken together, these studies in humans do not support the notion from animal studies that these two neurotransmitters interact on cognitive functions.

Semantic and phonological schema influence spoken word learning and overnight consolidation

We studied the initial acquisition and overnight consolidation of new spoken words that resemble words in the native language (L1) or in an unfamiliar, non-native language (L2). Spanish-speaking participants learned the spoken forms of novel words in their native language (Spanish) or in a different language (Hungarian), which were paired with pictures of familiar or unfamiliar objects, or no picture. We thereby assessed, in a factorial way, the impact of existing knowledge (schema) on word learning by manipulating both semantic (familiar vs unfamiliar objects) and phonological (L1- vs L2-like novel words) familiarity. Participants were trained and tested with a 12-hr intervening period that included overnight sleep or daytime awake. Our results showed (1) benefits of sleep to recognition memory that were greater for words with L2-like phonology and (2) that learned associations with familiar but not unfamiliar pictures enhanced recognition memory for novel words. Implications for complementary systems accounts of word learning are discussed.

Rapid L2 Word Learning through High Constraint Sentence Context: An Event-Related Potential Study

Previous studies have found quantity of exposure, i.e., frequency of exposure (Horst et al., 1998; Webb, 2008; Pellicer-Sánchez and Schmitt, 2010), is important for second language (L2) contextual word learning. Besides this factor, context constraint and L2 proficiency level have also been found to affect contextual word learning (Pulido, 2003; Tekmen and Daloglu, 2006; Elgort et al., 2015; Ma et al., 2015). In the present study, we adopted the event-related potential (ERP) technique and chose high constraint sentences as reading materials to further explore the effects of quantity of exposure and proficiency on L2 contextual word learning. Participants were Chinese learners of English with different English proficiency levels. For each novel word, there were four high constraint sentences with the critical word at the end of the sentence. Learners read sentences and made semantic relatedness judgment afterwards, with ERPs recorded. Results showed that in the high constraint condition where each pseudoword was embedded in four sentences with consistent meaning, N400 amplitude upon this pseudoword decreased significantly as learners read the first two sentences. High proficiency learners responded faster in the semantic relatedness judgment task. These results suggest that in high quality sentence contexts, L2 learners could rapidly acquire word meaning without multiple exposures, and L2 proficiency facilitated this learning process.

Does the late positive component reflect successful reading acquisition? A longitudinal ERP study

Developmental dyslexia is a reading disorder that is associated with deficits in phonological processing, where the exact neural basis for those processing deficits remains unclear. In particular, disagreement exists whether degraded phonological representations or an impaired access to the phonological representations causes these deficits. To investigate this question and to trace changes in neurophysiology during the process of reading acquisition, we designed a longitudinal study with event related potentials (ERPs) in children between kindergarten and second grade. We used an explicit word processing task to elicit the late positive component (LPC), which has been shown to reflect phonological processing. A brain-wide analysis of the LPC with an electrode-wise application of mixed effects models showed significantly attenuated amplitudes in the left temporo-parietal region in dyslexic children. Since these differences were only present in the word and not in the picture (i.e. control) condition, the attenuated amplitudes might reflect impaired access to the phonological representations of words. This was further confirmed by the longitudinal development, which showed a rapid increase in amplitude at the beginning of reading instruction and a decrease with continuing automatization, possibly pointing to a progression from grapheme-phoneme parsing to whole word reading. Our longitudinal study provides the first evidence that it is possible to detect neurophysiological differences in the LPC between children with dyslexia and control children in both preliterate and very early stages of reading acquisition, providing new insights about the neurophysiological development and a potential marker of later reading problems.

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First longitudinal study of the late positive component (LPC)

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Left temporo-parietal LPC differs between control and dyslexic children.

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LPC increase at reading acquisition and decrease with automatization in typical readers.

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Dyslexic children do not show this neurophysiological course of development.

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Findings might indicate an impaired access to phonological representations.

Neurophysiological evidence for the interplay of speech segmentation and word-referent mapping during novel word learning

Learning a new language requires the identification of word units from continuous speech (the speech segmentation problem) and mapping them onto conceptual representation (the word to world mapping problem). Recent behavioral studies have revealed that the statistical properties found within and across modalities can serve as cues for both processes. However, segmentation and mapping have been largely studied separately, and thus it remains unclear whether both processes can be accomplished at the same time and if they share common neurophysiological features. To address this question, we recorded EEG of 20 adult participants during both an audio alone speech segmentation task and an audiovisual word-to-picture association task. The participants were tested for both the implicit detection of online mismatches (structural auditory and visual semantic violations) as well as for the explicit recognition of words and word-to-picture associations. The ERP results from the learning phase revealed a delayed learning-related fronto-central negativity (FN400) in the audiovisual condition compared to the audio alone condition. Interestingly, while online structural auditory violations elicited clear MMN/N200 components in the audio alone condition, visual-semantic violations induced meaning-related N400 modulations in the audiovisual condition. The present results support the idea that speech segmentation and meaning mapping can take place in parallel and act in synergy to enhance novel word learning.

Inefficient stimulus processing at encoding affects formation of high-order general representation: A study on cross-modal word-stem completion task

Priming is an implicit memory effect in which previous exposure to one stimulus influences the response to another stimulus. The main characteristic of priming is that it occurs without awareness. Priming takes place also when the physical attributes of previously studied and test stimuli do not match; in fact, it greatly refers to a general stimulus representation activated at encoding independently of the sensory modality engaged. Our aim was to evaluate whether, in a cross-modal word-stem completion task, negative priming scores could depend on inefficient word processing at study and therefore on an altered stimulus representation. Words were presented in the auditory modality, and word-stems to be completed in the visual modality. At study, we recorded auditory ERPs, and compared the P300 (attention/memory) and N400 (meaning processing) of individuals with positive and negative priming. Besides classical averaging-based ERPs analysis, we used an ICA-based method (ErpICASSO) to separate the potentials related to different processes contributing to ERPs. Classical analysis yielded significant difference between the two waves across the whole scalp. ErpICASSO allowed separating the novelty-related P3a and the top-down control-related P3b sub-components of P300. Specifically, in the component C3, the positive deflection identifiable as P3b, was significantly greater in the positive than in the negative priming group, while the late negative deflection corresponding to the parietal N400, was reduced in the positive priming group. In conclusion, inadequacy of specific processes at encoding, such as attention and/or meaning retrieval, could generate weak semantic representations, making words less accessible in subsequent implicit retrieval.

Proficiency and sentence constraint effects on second language word learning

This paper presents an experiment that investigated the effects of L2 proficiency and sentence constraint on semantic processing of unknown L2 words (pseudowords). All participants were Chinese native speakers who learned English as a second language. In the experiment, we used a whole sentence presentation paradigm with a delayed semantic relatedness judgment task. Both higher and lower-proficiency L2 learners could make use of the high-constraint sentence context to judge the meaning of novel pseudowords, and higher-proficiency L2 learners outperformed lower-proficiency L2 learners in all conditions. These results demonstrate that both L2 proficiency and sentence constraint affect subsequent word learning among second language learners. We extended L2 word learning into a sentence context, replicated the sentence constraint effects previously found among native speakers, and found proficiency effects in L2 word learning.

Contextual learning of L2 word meanings: Second language proficiency modulates behavioural and ERP indicators of learning

New word learning occurs incidentally through exposure to language. Hypothesizing that effectiveness of contextual word learning in a second language (L2) depends on the quality of existing lexical semantic knowledge, we tested more and less proficient adult bilinguals in an incidental word learning task. One day after being exposed to rare words in an L2 (English) reading task, the bilinguals read sentences with the newly-learned words in the sentence-final position, followed by related or unrelated meaning probes. Both proficiency groups showed some learning through faster responses on related trials and a frontal N400 effect observed during probe word reading. However, word learning was more robust for the higher-proficiency group, who showed a larger semantic relatedness effect in unfamiliar contexts and a canonical N400 (central-parietal). The results suggest that the ability to learn the meanings of new words from context depends on the L2 lexical semantic knowledge of the reader.

Learning word meanings: overnight integration and study modality effects

According to the complementary learning systems (CLS) account of word learning, novel words are rapidly acquired (learning system 1), but slowly integrated into the mental lexicon (learning system 2). This two-step learning process has been shown to apply to novel word forms. In this study, we investigated whether novel word meanings are also gradually integrated after acquisition by measuring the extent to which newly learned words were able to prime semantically related words at two different time points. In addition, we investigated whether modality at study modulates this integration process. Sixty-four adult participants studied novel words together with written or spoken definitions. These words did not prime semantically related words directly following study, but did so after a 24-hour delay. This significant increase in the magnitude of the priming effect suggests that semantic integration occurs over time. Overall, words that were studied with a written definition showed larger priming effects, suggesting greater integration for the written study modality. Although the process of integration, reflected as an increase in the priming effect over time, did not significantly differ between study modalities, words studied with a written definition showed the most prominent positive effect after a 24-hour delay. Our data suggest that semantic integration requires time, and that studying in written format benefits semantic integration more than studying in spoken format. These findings are discussed in light of the CLS theory of word learning.

Low working memory capacity is only spuriously related to poor reading comprehension

Accounts of comprehension failure, whether in the case of readers with poor skill or when syntactic complexity is high, have overwhelmingly implicated working memory capacity as the key causal factor. However, extant research suggests that this position is not well supported by evidence on the span of active memory during online sentence processing, nor is it well motivated by models that make explicit claims about the memory mechanisms that support language processing. The current study suggests that sensitivity to interference from similar items in memory may provide a better explanation of comprehension failure. Through administration of a comprehensive skill battery, we found that the previously observed association of working memory with comprehension is likely due to the collinearity of working memory with many other reading-related skills, especially IQ. In analyses which removed variance shared with IQ, we found that receptive vocabulary knowledge was the only significant predictor of comprehension performance in our task out of a battery of 24 skill measures. In addition, receptive vocabulary and non-verbal memory for serial order-but not simple verbal memory or working memory-were the only predictors of reading times in the region where interference had its primary affect. We interpret these results in light of a model that emphasizes retrieval interference and the quality of lexical representations as key determinants of successful comprehension.

Using semantics to enhance new word learning: an ERP investigation

This study aimed to investigate whether the addition of meaning (semantics) would enhance new word learning for novel objects, and whether it would influence the neurophysiological response to new words. Twenty-five young healthy adults underwent 4 days of training to learn the names of 80 novel objects. Half of the items were learnt under a 'semantic' condition, whereby the name consisted of a legal nonword and two adjectives denoting semantic attributes. The remaining items were learnt under a 'name' condition, whereby the name consisted of a legal nonword and two proper names. Participants demonstrated superior recognition of names in the semantic condition compared to the name condition during training sessions 1-3. On the 5th day, following training, ERPs were recorded whilst participants performed a picture-word judgement task including familiar items. Analysis of the results revealed an N400 for incongruent items in the semantic condition, whilst no ERP component was observed for the name condition. These findings suggest that items learnt with semantic information form stronger associations than those trained without semantics.

The time course of reading processes in children with and without dyslexia: an ERP study

The main diagnostic criterion for developmental dyslexia (DD) in transparent orthographies is a remarkable reading speed deficit, which is often accompanied by spelling difficulties. These deficits have been traced back to both deficits in orthographic and phonological processing. For a better understanding of the reading speed deficit in DD it is necessary to clarify which processing steps are degraded in children with DD during reading. In order to address this question the present study used EEG to investigate three reading related ERPs: the N170, N400 and LPC. Twenty-nine children without DD and 52 children with DD performed a phonological lexical decision (PLD)-task, which tapped both orthographic and phonological processing. Children were presented with words, pseudohomophones, pseudowords and false fonts and had to decide whether the presented stimulus sounded like an existing German word or not. Compared to control children, children with DD showed deficits in all the investigated ERPs. Firstly, a diminished mean area under the curve for the word material-false font contrasts in the time window of the N170 was observed, indicating a reduced degree of print sensitivity; secondly, N400 amplitudes, as suggested to reflect the access to the orthographic lexicon and grapheme-phoneme conversion, were attenuated; and lastly, phonological access as indexed by the LPC was degraded in children with DD. Processing differences dependent on the linguistic material in children without DD were observed only in the LPC, suggesting that similar reading processes were adopted independent of orthographic familiarity. The results of this study suggest that effective treatment should include both orthographic and phonological training. Furthermore, more longitudinal studies utilizing the same task and stimuli are needed to clarify how these processing steps and their time course change during reading development.

Concreteness effects in single-meaning, multi-meaning and newly acquired words

This study examined the extent to which concreteness influences the acquisition and subsequent processing of novel (low frequency) concepts. Participants were trained on 70 rare English words (35 concrete, 35 abstract) paired with definitions. ERPs were then recorded while participants performed a semantic categorisation (concrete vs. abstract) and a lexical decision task on single-meaning, multi-meaning and the newly acquired words. During training there was a significant effect of concreteness, in that participants were more successful at acquiring concrete concepts. In both the semantic categorisation and the lexical decision task, concreteness effects were evident in the behavioural and in the ERP data for all word types, with concrete words eliciting more negative waveforms than abstract words in the N400 time window. Behaviourally, participants experienced greater difficulty in judging the concreteness of multi-meaning words, yet concreteness effects in the N400 were equally strong for all three word types across both tasks. These findings indicate that concreteness represents a fundamental distinction in the way that items are represented in memory, which is independent of the participant's perceived judgement. They further demonstrate that novel concepts can be acquired rapidly after minimal training, and that the neurophysiological correlates associated with processing novel words are modulated by the specific nature of the conceptual characteristics assigned to the word.