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Background: Alzheimer's Research UK reports 850,000 individuals are living with dementia in the UK today and this is estimated to increase to one million by 2025. Alzheimer's Disease (AD), a type of dementia, accounts for approximately 60% of all diagnoses and as yet, there is no cure. Diagnosis rates in high income countries are below half and achieving acceptable levels of coverage and access to care is the challenge currently being faced (World Health Organization, 2015). Mild cognitive impairment (MCI) is a pre-clinical form of AD (Petersen, 2011) and is manifested by mild symptoms affecting cognitive function, without interference in daily activities. Neurodegeneration, defined by synaptic dysfunction, occurs decades prior to any symptoms emerging (Albert et al., 2011) interrupting electrical communication between neurones. Methods: A multi assessment approach using a wireless, dry-EEG system was used to explore the potential of recording brain activity outside the laboratory and in a more informal setting. Participants with MCI and neurotypical controls completed a neuropsychological assessment and computerized tasks designed to probe cognitive function where deficits are expected in MCI. Event related potential technique was applied to the EEG and features of interest were extracted for further analysis using supervised machine learning methods. Analysis and Results: Analysis was carried out on a group level and individual level. The latter involved training algorithms on a range of data models to identify patterns in the data with feature combinations predicting group membership of individuals with accuracy. Randomisation tests confirmed that there no differences found at a group level when considering the groups' performance during episodic memory, language, executive function (working memory) or attention tasks. For analysis at an individual level, improved model accuracies with the addition of ERP features to neuropsychological features were reported for the language and attention task. A combination of features, namely an ERP feature and neuropsychological feature were selected by the algorithms as features contributing to the best model. Discussion: The four EEG tasks in this study were designed to probe cognitive function known to deteriorate in individuals with MCI. Considering the trajectory of cognitive decline is essential when interpreting differences, or indeed no differences between the groups. However, a difference between the groups with respect to episodic memory would have been expected since it is the cognitive function upon which their diagnosis is based: this finding most likely points to the low power of the study. Feature selection was of interest across the tasks and provided insight into potential predictors of progression to AD relative to the cognitive function. However, due to the heterogeneity of MCI, it is with caution that these features are discussed since it is unknown who within the MCI group would progress to AD. Conclusion: The study was a proof of concept exploring cognitive function using a wireless dry-EEG headset outside a laboratory or hospital setting. The benefits of this system included a quick and easy set-up without compromising the quality of data. This approach could provide an efficient and affordable way to extend research into more accessible locations such as health centres and at home.

Despite large strides in our understanding of bilingual language processing at the lexical and syntactic level, including activation in L1/L2 and co-activation of languages (RHM, Kroll and Stewart, 1994; BIA - Dijkstra & Van Heuven & Grainger, 1998; BIA+, Dijkstra & Van Heuven, 2002), relatively little is known about the structure and activation of bilingual semantics. Current models provide at best a sketchy account of how the two languages compare and potentially interact at the level of meaning (The Sense Model, Finkbeiner et al, 2004; The distributed Feature Model, de Groot, 1992), and it is imperative that more empirical work is done to ascertain a more detailed picture of bilingual semantics (Multilink, Dijkstra et al, 2018). The empirical work presented in this thesis therefore aims to examine whether stronger conceptual links in the L1 afford less processing effort to achieve intra-sense conceptual mapping than in L2 (Part 1), and whether the bilingual inter-sense mapping includes co-activations of meaning (Part 2). Crucially, we use sentence processing throughout in a bid to provide an account of bilingual semantics beyond the lexical level.

Difficulties in speech production are often marked by disfluency; fillers, hesitations, prolongations, repetitions and repairs. In recent years a body of work has emerged that demonstrates that listeners are sensitive to disfluency, and that this affects their expectations for upcoming speech, as well as their attention to the speech stream. This thesis investigates the extent to which delay may be responsible for triggering these effects. The experiments reported in this thesis build on an Event Related Potential (ERP) paradigm developed by Corley et al., (2007), in which participants listened to sentences manipulated by both fluency and predictability. Corley et al. reported an attenuated N400 effect for words following disfluent ers, and interpreted this as indicating that the extent to which listeners made predictions was reduced following an er. In the current set of experiments, various noisy interruptions were added to Corley et al.,'s paradigm, time matched to the disfluent fillers. These manipulations allowed investigation of whether the same effects could be triggered by delay alone, in the absence of a cue indicating that the speaker was experiencing difficulty. The first experiment, which contrasted disfluent ers with artificial beeps, revealed a small but significant reduction in N400 effect amplitude for words affected by ers but not by beeps. The second experiment, in which ers were contrasted with speaker generated coughs, revealed no fluency effects on the N400 effect. A third experiment combined the designs of Experiments 1 and 2 to verify whether the difference between them could be characterised as a context effect; one potential explanation for the difference between the outcomes of Experiments 1 and 2 is that the interpretation of an er is affected by the surrounding stimuli. However, in Experiment 3, once again no effect of fluency on the magnitude of the N400 effect was found. Taken together, the results of these three studies lead to the question of whether er's attenuation effect on the N400 is robust. In a second part to each study, listeners took part in a surprise recognition memory test, comprising words which had been the critical words in the previous task intermixed with new words which had not appeared anywhere in the sentences previously heard. Participants were significantly more successful at recognising words which had been unpredictable in their contexts, and, importantly, for Experiments 1 and 2, were significantly more successful at recognising words which had featured in disfluent or interrupted sentences. There was no difference between the recognition rates of words which had been disfluent and those which were affected by a noisy interruption. Collard et al., (2008) demonstrated that disfluency could raise attention to the speech stream, and the finding that interrupted words are equally well remembered leads to the suggestion that any noisy interruption can raise attention. Overall, the finding of memory benefits in response to disfluency, in the absence of attenuated N400 effects leads to the suggestion that different elements of disfluencies may be responsible for triggering these effects. The studies in this thesis also extend previous work by being designed to yield enough trials in the memory test portion of each experiment to permit ERP analysis of the memory data. Whilst clear ERP memory effects remained elusive, important progress was made in that memory ERPs were generated from a disfluency paradigm, and this provided a testing ground on which to demonstrate the use of linear mixed-effects modelling as an alternative to ANOVA analysis for ERPs. Mixed-effects models allow the analysis of unbalanced datasets, such as those generated in many memory experiments. Additionally, we demonstrate the ability to include crossed random effects for subjects and items, and when this is applied to the ERPs from the listening section of Experiment 1, the effect of fluency on N400 amplitude is no longer significant. Taken together, the results from the studies reported in this thesis suggest that temporal delay or disruption in speech can trigger raised attention, but do not necessarily trigger changes in listeners' expectations.

This work concerns the investigation of the neuronal mechanisms at the basis of language acquisition and processing, and the complex interactions of language and attention processes in the human brain. In particular, this research was motivated by two sets of existing neurophysiological data which cannot be reconciled on the basis of current psycholinguistic accounts: on the one hand, the N400, a robust index of lexico-semantic processing which emerges at around 400ms after stimulus onset in attention demanding tasks and is larger for senseless materials (meaningless pseudowords) than for matched meaningful stimuli (words); on the other, the more recent results on the Mismatch Negativity (MMN, latency 100-250ms), an early automatic brain response elicited under distraction which is larger to words than to pseudowords. We asked what the mechanisms underlying these differential neurophysiological responses may be, and whether attention and language processes could interact so as to produce the observed brain responses, having opposite magnitude and different latencies. We also asked questions about the functional nature and anatomical characteristics of the cortical representation of linguistic elements. These questions were addressed by combining neurocomputational techniques and neuroimaging (magneto-encephalography, MEG) experimental methods. Firstly, a neurobiologically realistic neural-network model composed of neuron-like elements (graded response units) was implemented, which closely replicates the neuroanatomical and connectivity features of the main areas of the left perisylvian cortex involved in spoken language processing (i.e., the areas controlling speech output – left inferior-prefrontal cortex, including Broca’s area – and the main sensory input – auditory – areas, located in the left superior-temporal lobe, including Wernicke’s area). Secondly, the model was used to simulate early word acquisition processes by means of a Hebbian correlation learning rule (which reflects known synaptic plasticity mechanisms of the neocortex). The network was “taught” to associate pairs of auditory and articulatory activation patterns, simulating activity due to perception and production of the same speech sound: as a result, neuronal word representations distributed over the different cortical areas of the model emerged. Thirdly, the network was stimulated, in its “auditory cortex”, with either one of the words it had learned, or new, unfamiliar pseudoword patterns, while the availability of attentional resources was modulated by changing the level of non-specific, global cortical inhibition. In this way, the model was able to replicate both the MMN and N400 brain responses by means of a single set of neuroscientifically grounded principles, providing the first mechanistic account, at the cortical-circuit level, for these data. Finally, in order to verify the neurophysiological validity of the model, its crucial predictions were tested in a novel MEG experiment investigating how attention processes modulate event-related brain responses to speech stimuli. Neurophysiological responses to the same words and pseudowords were recorded while the same subjects were asked to attend to the spoken input or ignore it. The experimental results confirmed the model’s predictions; in particular, profound variability of magnetic brain responses to pseudowords but relative stability of activation to words as a function of attention emerged. While the results of the simulations demonstrated that distributed cortical representations for words can spontaneously emerge in the cortex as a result of neuroanatomical structure and synaptic plasticity, the experimental results confirm the validity of the model and provide evidence in support of the existence of such memory circuits in the brain. This work is a first step towards a mechanistic account of cognition in which the basic atoms of cognitive processing (e.g., words, objects, faces) are represented in the brain as discrete and distributed action-perception networks that behave as closed, independent systems.

The N400 and P600 components of cognitive evoked potentials or event-related potentials (ERP) are context related and usually recordable after a priming stimulus or context consisting of words or any meaningful stimuli. All studies previous to this one used a sequential presentation of stimuli to elicit the ERPs. In this study, however, the picture and word stimuli were presented simultaneously. ERPs were recorded from 79 neurologically normal subjects including 62 right-handed, 10 left-handed and 7 subjects who were suffering from temporal lobe brain damage. Subjects were either asked to respond as to whether the stimuli were congruent, incongruent or non-sensical (semantic incongruency) or as to whether they were 'new' or 'old' (recognition memory). The number of correct responses and the reaction time were both measured. ERPs were recorded using an electrode cap which consisted of 16-channel scalp electrode montage (an enhanced international 10/20 electrode placement system) with linked mastoids as reference electrodes. Data was acquired and analysed using Neuroscan signal averaging and mapping software. In all the experimental conditions studied the tasks were performed accurately but reaction time was significantly longer for the incongruent stimuli. The same occurred for 'new' items as opposed to 'old' items. In the ERP recordings the N400 and P600 components were independent. The N400 peak was recorded maximally over the frontal locations while the P600 was mainly a parietal component. Differences were observed in their latency, amplitude and spatial distribution within the various test conditions.

Across cognitive systems, world knowledge allows individuals to organize raw sensation into meaningful experiences. Language processing is no exception—words cue world knowledge which can be rapidly brought to mind in real time. It stands to reason that how much and how well individuals know things will impact what each individual brings to mind during real-time comprehension; yet to date, models of real-time language processing have not taken this variability into account. We addressed this issue by studying a linguistically rich, yet constrained, popular domain—the fictional world of Harry Potter (HP), by J.K. Rowling. In a series of three studies, we recorded event-related brain potentials (ERPs) while young adults who varied in their knowledge of HP read sentences about HP “facts” and/or sentences describing general topics. As a measure of real-time knowledge retrieval, we focused on N400 amplitude, a brain potential with a centro-parietal maximum occurring ~250-500 ms post stimulus onset that is sensitive to factors impacting the ease of retrieval from semantic memory, with larger reductions in N400 (i.e., more positive-going N400 potentials) associated with greater ease of retrieval.Across all three studies, we found that individuals’ domain knowledge of HP (assessed via an offline multiple-choice trivia quiz) was moderately-to-strongly correlated with average N400 brain potentials to contextually supported (i.e., accurate) words completing sentences about HP, but not to unsupported (inaccurate) endings, nor to N400 effects (i.e., difference ERPs) of more vs. less supported endings to sentences describing general topics (Experiments 1 and 3). Single-trial regression analyses pitting domain knowledge against participants’ reports of knowledge about each HP “fact” (i.e., whether or not they had known each fact ahead of reading it) revealed trial-level knowledge was a strong, but not the sole, predictor of N400 amplitudes to supported words (Experiment 2). Rather, even after accounting for trial-level knowledge reports, and especially when retrieval conditions were presumably more difficult (i.e., for trials reported as unknown by an individual or those generally less likely to be known across participants), N400 amplitudes were modulated by individuals’ domain knowledge of HP. We hypothesized that degree of domain knowledge might modulate real-time semantic retrieval by virtue of the differential organization of that information in semantic memory—for example, functionally organized around events and categories, as has been proposed more generally in the literature on expert knowledge.In Experiment 3, we therefore manipulated the relationship between the final (critical) words of HP sentences and their sentence contexts according to these organizational structures. Critical words (each of which appeared across conditions) were supported continuations, unsupported/unrelated continuations, or unsupported continuations that were related via an HP-specific category to the supported ending or to the event/episode being described by the sentence context. Individuals with greater HP domain knowledge showed reduced N400 amplitudes not only to supported words, but also to unsupported but contextually related words (for both types of relationships), compared to the unsupported unrelated words. That is, domain knowledge systematically influenced the quick availability of functionally (categorically, event-based) related knowledge during written sentence comprehension.Our results provide the first empirical demonstration that real-time retrieval of knowledge during reading is determined by how much information is known and which facts are readily available to an individual comprehender. Domain knowledge seems to influence implicit retrieval of (perhaps) partial information (Experiment 2) and the availability of relevant/related information (Experiment 3)—the very information that is needed to make sense of words in real time. We hypothesize that variation in domain knowledge leads to systematic variation in hallmark organizational structures of semantic memory, including organization of categories and events, which in turn influence the degree to which relevant information can be (pre-)activated in order to make sense of words in real time.

Languages can be divided into two types based on how they express motion events. Some languages, like English, tend to express manner of motion in the verb and path of motion outside the verb. Other languages, like Spanish, tend to express path of motion in the verb and only express manner rarely in subordinated or separate clauses. Behavioral research has examined whether these differences in expression lead to crosslinguistic differences in the sensitivity to manner versus path information in cognition; however, these studies have led to inconclusive results. To date, no study has examined the neural correlates associated with either the lexicalization of motion information nor to the sensitivity of motion information processing. As such, the current study examines the event-related potentials (ERPs) associated with the processing of grammatical but atypical patterns of lexicalization and sensitivity to violations of expectancy for motion expression (congruency with a preceding animation) in adult native speakers of English and Spanish by examining the N400 (marker of semantic expectancy) and the P600 (marker of syntactic congruity that has recently been implicated in certain semantic errors). I predicted that atypical lexicalization patterns would produce larger ERP effects compared to typical patterns, and ERP effects would be larger for motion information to which speakers were more sensitive. Rather than the traditionally predicted N400 effects to atypical lexicalizations, the results showed greater P600 effects. Similarly, analyses of sensitivity to motion expression violations revealed greater P600—as opposed to N400—amplitudes in response to incongruent compared to congruent motion verbs in both languages as well as both an N400 and P600 effect in path prepositions in English. In contrast, manner expressed outside the verb (gerunds) in both languages and path expressed outside the verb in Spanish (prepositions, adverbs) produced the traditional N400 effect for incongruent compared to congruent expressions. While these results do not provide support for the idea that habitual expression increases sensitivity to that type of information, it does suggest that speakers are sensitive to those lexical patterns. More interestingly, it suggests that the P600 may be sensitive to a broader range of stimuli than previously predicted.

Two studies were performed to investigate the temporal structure and organization of the language processing system during the comprehension of coherent contextually ambiguous narrative discourses. In Study 1, participants read short discourses that were contextually ambiguous if read without a descriptive title (Untitled group) or unambiguous with the title (Titled group). Participants identified the title of the discourses after reading 1-3 sentences. Given the unfinished next sentence, they performed a cloze procedure on the sentence-final word. For the Titled Group, cloze probability was greater to the last word of sentence 3 (Critical Word 3) than sentences 2 (Critical Word 2) and 1 (Critical Word 1). For the Untitled group, title identification accuracy was greater after reading the first two sentences than the first sentence and even more so after reading the full three-sentence discourses than the first two sentences alone. This study established 25 discourses in which the contexts were initially ambiguous but became increasingly clearer after reading Critical Word 2 and Critical Word 3. In Study 2, a different sample of participants read the discourses with (Titled Discourse group) or without (Untitled Discourse group) a descriptive title while undergoing high-density event-related potential (ERP) recording. For the Untitled Discourse group, N400 amplitudes became less negative from Critical Word 1 to Critical Word 2 and again to Critical Word 3, suggesting greater ease of lexical-semantic retrieval as the discourses unfolded. For this group, P600 amplitudes were larger to Critical Word 3 than Critical Word 2. Unexpectedly, a Late Sustained Frontal Positivity (SFP) ERP component occurred to both Critical Word 2 and Critical Word 3 for the Untitled Discourse group only. SFP results corresponded to the title identification findings from Study 1. Thus, it is proposed that the SFP reflects the resolution or revision of contextual ambiguity during discourse comprehension. Alternatively, the P600 is proposed to reflect the updating of the existing context of a discourse when an context is available or after the resolution of contextual ambiguity. Advisors: Dennis L. Molfese and Art C. Maerlender

Abstract: Background. Context use in sentence comprehension is fairly resistant to age-related cognitive decline; however, event-related potentials (ERPs) studies have shown age effects in neural activity associated with sentence comprehension, specifically when contextual information is manipulated. One well-documented ERP component, N400, may reflect the use of context to predict upcoming words. Older adults have smaller and later N400 responses than younger adults for unexpected sentence-endings (Federmeier et al., 2002), suggesting age-related differences in how adults use context. As well, there is the post-N400 positivity (PNP) – both at the frontal and parietal regions - that may index attempted re-analysis of incongruent sentences, or reflect predictive processing, which is also influenced by age (Van Petten & Luka, 2012). The purpose of the present study is to determine whether there are age-related differences in reading comprehension of sentences with varying semantic anomalies, using electroencephalography methods. Methods. Experiment 1 was designed as a pilot study, to investigate whether a passive reading paradigm would elicit the anticipated ERP responses. In Experiment 1, neurologically healthy young adults (n = 34; age range 18 – 30 years, M = 23.8, SD = 3.05) passively read pairs of sentences while wearing an electroencephalography cap. In Experiment 2, EEG was recorded while young (n = 22; age range 18 – 27 years, M = 21.1, SD = 2.62) and older (n = 21; age range 50 to 84 years, M = 62.0, SD = 8.98) adults read the same pairs of sentences as in Experiment 1, followed by a recognition memory task where they had to identify the presented sentence-ending word in order to elicit active processing of the stimuli. In both experiments, the reading task consisted of the presentation of two sentences. The first sentence established the context. The second sentence ended with a target word that was either 1) expected, 2) unexpected but semantically related, or 3) unexpected and unrelated to the context. The amplitude and latency of the N400 and PNP were measured using electroencephalography for the final target word, in each experiment. Reading time and recognition memory accuracy (Experiment 2) was also measured. Results. In Experiment 1, there was no significant N400 effect for the three sentence ending conditions. However, we detected a parietal PNP response in terms of mean amplitude. In Experiment 2, there were no significant differences in the behavioural measures between young and older adults (reading time and memory performance), as anticipated. Younger and older adults demonstrated maximal N400 responses for unexpected-unrelated words and minimal N400 responses for expected words. The latency of the N400 response was different between the groups, in which older adults had delayed processing in the earlier time window. Both groups of adults also demonstrated parietal post-N400 positivity (PNP) responses, contrary to previous literature. Discussion. Younger and older adults performed similarly on behavioural measures and the N400 results indicated that older adults are able to use their semantic memory to assess the stimuli features similar to young adults. However, there was evidence for age-related differences in the N400 latency. The parietal PNP responses also showed differences in the processing of the stimuli between young and older adults. Overall, our findings are important for understanding the neural correlates underlying age effects on context use in sentence comprehension. As reading plays a vital role in our society, understanding how aging affects this ability will provide new insights into the corresponding neural mechanisms, with possible implications for clinical populations with reading impairments.

Abstract: Background. According to dual-route models of reading, there are two pathways with which words can be read: an orthographic-lexical pathway used to read familiar regular words and exception (EXC) words, and a grapheme-to-phoneme-conversion (GPC)-sublexical pathway used to read unfamiliar regular words, pseudohomophones (PHs), and nonwords. A recent debate in the reading literature has centered on whether individuals access lexical and semantic representations of letter strings similarly depending on which reading pathway is used. This has been explored via the Stroop paradigm (Stroop, 1935/1992), in which participants name the font colours of words while ignoring what the words say (i.e., reading without intention). We extend previous research by measuring an event-related potential (ERP), the N400, a brain waveform that has been suggested to be involved in the processing of semantic information. Method. The present study explored lexical-semantic access while participants read without intention, using four different types of stimuli that forced readers to use the orthographic-lexical or GPC-sublexical pathways. The experiment examined twenty-four neurologically normal individuals. The amplitude and latency of the N400 were measured using electroencephalography (EEG), and response time and error rate were also measured behaviourally. Results. In the behavioural data, evidence was found of a significant Stroop effect whereby readers were faster to identify the colour of congruent letter strings compared to incongruent letter strings. In the ERP data, the N400 was found as hypothesized. However, contrary to previous findings in the N400 literature, congruent trials exhibited greater negative peak amplitudes then incongruent trials in several different time windows. Conclusions: Both the behavioural data and the finding of an N400 suggest that individuals access lexical and semantic representations without intention regardless of the reading pathway being used. As literacy and the ability to read play a large role in Western society, the results of the current study have important implications as they provide new information on how orthographic-lexical and GPC-sublexical reading processes operate in skilled readers, with possible ramifications for individuals with reading impairments. Thus, the results have theoretical implications not only for cognitive models of reading, but also for improving our understanding of how to help people with developmental and acquired reading disorders.

In the present study, we conducted an event-related potentials (ERP) study to examine episodic and semantic memory. We focused on two well-known patterns: the semantic N400 and the old/new fN400. Some researchers have argued that they reflect the same neuropsychological response (Voss & Federmeier, 2011). Others have suggested that they have distinct spatial-temporal signatures and reflect different psychological processes (Bridger, Bader, Kriukova, Unger, & Mecklinger, 2012). In the present study, we analyzed data using the basic N400/fN400 paradigm. We expect to find similar results to Bridger et al. (2012) in that the N400 and fN400 to be reliably different in topography and function.

The present study utilized a cross-modal priming paradigm to investigate dimensional information processing in speech. Primes were facial expressions that varied in two dimensions: affect (happy, neutral, or angry) and mouth shape (corresponding to either /a/ or /i/ vowels). Targets were CVC words that varied by prosody and vowel identity. In both the phonetic and prosodic conditions, adult participants responded to congruence or incongruence of the visual-auditory stimuli. Behavioral results showed a congruency effect in percent correct and reaction time measures. Two ERP responses, the N400 and late positive response, were identified for the effect with systematic between-condition differences. Localization and time-frequency analyses indicated different cortical networks for selective processing of phonetic and emotional information in the words. Overall, the results suggest that cortical processing of phonetic and emotional information involves distinct neural systems, which has important implications for further investigation of language processing deficits in clinical populations.

We describe a statistical language model having components that are inspired by electrophysiological activities in the brain. These components correspond to important language-relevant event-related potentials measured using electroencephalography. We relate neural signals involved in local- and long-distance grammatical processing, as well as local- and long-distance lexical processing to statistical language models that are scalable, cross-linguistic, and incremental. We develop a novel language model component that unifies n-gram, skip, and trigger language models into a generalized model inspired by the long-distance lexical event-related potential (N400). We evaluate this model in textual and speech recognition experiments, showing consistent improvements over 4-gram modified Kneser-Ney language models for large-scale textual datasets in English, Arabic, Croatian, and Hungarian.

Previous research has indicated the important role of visual information in the speech perception process. These studies have elucidated the areas of the brain involved in the processing of audiovisual stimuli. The McGurk effect, an audiovisual illusion, has been demonstrated to be a useful tool in the study of audiovisual integration. Brain imaging research suggests that the McGurk effect is modulated by brain structures in the Superior Temporal Gyrus, Supplemental Temporal Cortex and Broadman area 41. Electrophysiological studies suggest that the McGurk effect generates a different brainwave than the standard audiovisual congruent condition in frontal, central and parietal regions among N1, P2, N300 and later ERP components. The magnitude of the McGurk effect is influenced by lexical information, cultural difference and language experience, although these effects have not been investigated by electrophysiological methods. The current study compares three experimental groups, native Chinese speakers who had less than three years of residency in the United States; native Chinese speakers with more than three years of residency in the United States; and native English speakers. A high density (256 channels) hydrocel system was used to collect the ERP data from the participants in three experiments. The main effect of McGurk was studied in Experiment 1, by dubbing an audio /ba/ onto a video /ga/. The behavioral responses and the characteristic brainwave of the McGurk effect were examined. The semantic and culturally related McGurk effects were investigated in Experiment 2 and 3. The three groups were contrasted in each of the experiments. The results showed brainwave differences for the McGurk and the standard audiovisual congruent condition in the left hemisphere. These results also revealed a word/nonword separation in the McGurk effect, which provides electrophysiological evidence for an interaction of the McGurk condition and semantic/cognitive processing. Contrary to hypothesis, significant group differences were not found between the two Chinese groups. Limitations and implications of this study are discussed.