Riding the lexical speedway: a critical review on the time course of lexical selection in speech production

A mapping-knowledge-domain analysis of ERP research on language processing

The event-related potentials (ERPs) technique represents a newly developed methodology in cognitive neuroscience and has significantly extended the scope of linguistic studies, offering valuable insights into cognitive processes related to language. While extant literature reviews have addressed specific facets of ERP research on language processing, a comprehensive overview of this domain remains notably absent. This study aims to fill this gap by pioneering a mapping-knowledge-domain analysis of ERP research on language processing using Citespace, a visualized bibliometric software. The current study conducted a meticulous survey and evaluation of relevant literature extracted from the Web of Science core collection. Initially, this study outlines the spatial-temporal distribution within this domain. Subsequently, employing document co-citation analysis, keyword co-occurrence analysis, cluster analysis, and burst detection analysis, this study delved deeper into the research landscape. Findings reveal that key areas in ERP research on language processing predominantly focus on sentence comprehension, reading comprehension, and mismatch negativity, with notable emphasis on topics such as speech perception, temporal dynamics, and working memory. The current study advocates for future investigations to concentrate on larger linguistic units, explore the integration of ERP components and their functional significance, and scrutinize individual differences among participants. These directions are imperative for advancing the understanding of language processing mechanisms.

Word frequency and cognitive effort in turns-at-talk: turn structure affects processing load in natural conversation

Frequency distributions are known to widely affect psycholinguistic processes. The effects of word frequency in turns-at-talk, the nucleus of social action in conversation, have, by contrast, been largely neglected. This study probes into this gap by applying corpus-linguistic methods on the conversational component of the British National Corpus (BNC) and the Freiburg Multimodal Interaction Corpus (FreMIC). The latter includes continuous pupil size measures of participants of the recorded conversations, allowing for a systematic investigation of patterns in the contained speech and language on the one hand and their relation to concurrent processing costs they may incur in speakers and recipients on the other hand. We test a first hypothesis in this vein, analyzing whether word frequency distributions within turns-at-talk are correlated with interlocutors' processing effort during the production and reception of these turns. Turns are found to generally show a regular distribution pattern of word frequency, with highly frequent words in turn-initial positions, mid-range frequency words in turn-medial positions, and low-frequency words in turn-final positions. Speakers' pupil size is found to tend to increase during the course of a turn at talk, reaching a climax toward the turn end. Notably, the observed decrease in word frequency within turns is inversely correlated with the observed increase in pupil size in speakers, but not in recipients, with steeper decreases in word frequency going along with steeper increases in pupil size in speakers. We discuss the implications of these findings for theories of speech processing, turn structure, and information packaging. Crucially, we propose that the intensification of processing effort in speakers during a turn at talk is owed to an informational climax, which entails a progression from high-frequency, low-information words through intermediate levels to low-frequency, high-information words. At least in English conversation, interlocutors seem to make use of this pattern as one way to achieve efficiency in conversational interaction, creating a regularly recurring distribution of processing load across speaking turns, which aids smooth turn transitions, content prediction, and effective information transfer.

Overt Word Reading and Visual Object Naming in Adults with Dyslexia: Electroencephalography Study in Transparent Orthography

The study aimed to investigate overt reading and naming processes in adult people with dyslexia (PDs) in shallow (transparent) language orthography. The results of adult PDs are compared with adult healthy controls HCs. Comparisons are made in three phases: pre-lexical (150-260 ms), lexical (280-700 ms), and post-lexical stage of processing (750-1000 ms) time window. Twelve PDs and HCs performed overt reading and naming tasks under EEG recording. The word reading and naming task consisted of sparse neighborhoods with closed phonemic onset (words/objects sharing the same onset). For the analysis of the mean ERP amplitude for pre-lexical, lexical, and post-lexical time window, a mixed design ANOVA was performed with the right (F4, FC2, FC6, C4, T8, CP2, CP6, P4) and left (F3, FC5, FC1, T7, C3, CP5, CP1, P7, P3) electrode sites, within-subject factors and group (PD vs. HC) as between-subject factor. Behavioral response latency results revealed significantly prolonged reading latency between HCs and PDs, while no difference was detected in naming response latency. ERP differences were found between PDs and HCs in the right hemisphere's pre-lexical time window (160-200 ms) for word reading aloud. For visual object naming aloud, ERP differences were found between PDs and HCs in the right hemisphere's post-lexical time window (900-1000 ms). The present study demonstrated different distributions of the electric field at the scalp in specific time windows between two groups in the right hemisphere in both word reading and visual object naming aloud, suggesting alternative processing strategies in adult PDs. These results indirectly support the view that adult PDs in shallow language orthography probably rely on the grapho-phonological route during overt word reading and have difficulties with phoneme and word retrieval during overt visual object naming in adulthood.

A neuro-cognitive model of comprehension based on prediction and unification

Most architectures and models of language processing have been built upon a restricted view of language, which is limited to sentence processing. These approaches fail to capture one primordial characteristic: efficiency. Many facilitation effects are known to be at play in natural situations such as conversation (shallow processing, no real access to the lexicon, etc.) without any impact on the comprehension. In this study, on the basis of a new model integrating into a unique architecture, we present these facilitation effects for accessing the meaning into the classical compositional architecture. This model relies on two mechanisms, prediction and unification, and provides a unique architecture for the description of language processing in its natural environment.

Tonal and syllabic encoding in overt Cantonese Chinese speech production: An ERP study

This study was conducted to investigate how syllables and lexical tones are processed in Cantonese speech production using the picture-word interference task with concurrent recording of event-related brain potentials (ERPs). Cantonese-speaking participants were asked to name aloud individually presented pictures and ignore an accompanying auditory word distractor. The target and distractor either shared the same word-initial syllable with the same tone (Tonal-Syllable related), the same word-initial syllable without the same tone (Atonal-Syllable related), the same tone only (Tone alone related), or were phonologically unrelated. Participants' naming responses were faster, relative to an unrelated control, when the target and distractor shared the same tonal- or atonal-syllable but null effect was found in the Tone alone related condition. The mean ERP amplitudes (per each 100-ms time window) were subjected to stimulus-locked (i.e., time-locked to stimulus onset) and response-locked (i.e., time-locked to response onset) analyses. Significant differences between related and unrelated ERP waves were similarly observed in both Tonal-Syllable related and Atonal-Syllable related conditions in the time window of 400-500 ms post-stimulus. However, distinct ERP effects were observed in these two phonological conditions within the 500-ms pre-response period. In addition, null effects were found in the Tone alone related condition in both stimulus-locked and response-locked analyses. These results suggest that in Cantonese spoken word production, the atonal syllable of the target is retrieved first and then associated with the target lexical tone, consistent with the view that tone has an important role to play at a late stage of phonological encoding in tonal language production.

Semantic Categorization of Naming Responses Based on Prearticulatory Electrical Brain Activity

PURPOSE

Object naming requires visual decoding, conceptualization, semantic categorization, and phonological encoding, all within 400 to 600 ms of stimulus presentation and before a word is spoken. In this study, we sought to predict semantic categories of naming responses based on prearticulatory brain activity recorded with scalp EEG in healthy individuals.

METHODS

We assessed 19 healthy individuals who completed a naming task while undergoing EEG. The naming task consisted of 120 drawings of animate/inanimate objects or abstract drawings. We applied a one-dimensional, two-layer, neural network to predict the semantic categories of naming responses based on prearticulatory brain activity.

RESULTS

Classifications of animate, inanimate, and abstract responses had an average accuracy of 80%, sensitivity of 72%, and specificity of 87% across participants. Across participants, time points with the highest average weights were between 470 and 490 milliseconds after stimulus presentation, and electrodes with the highest weights were located over the left and right frontal brain areas.

CONCLUSIONS

Scalp EEG can be successfully used in predicting naming responses through prearticulatory brain activity. Interparticipant variability in feature weights suggests that individualized models are necessary for highest accuracy. Our findings may inform future applications of EEG in reconstructing speech for individuals with and without speech impairments.

Word frequency has similar effects in picture naming and gender decision: A failure to replicate Jescheniak and Levelt (1994)

Word frequency plays a key role in theories of lexical access, which assume that the word frequency effect (WFE, faster access to high-frequency than low-frequency words) occurs as a result of differences in the representation and processing of the words. In a seminal paper, Jescheniak and Levelt (1994) proposed that the WFE arises during the retrieval of word forms, rather than the retrieval of their syntactic representations (their lemmas) or articulatory commands. An important part of Jescheniak and Levelt's argument was that they found a stable WFE in a picture naming task, which requires complete lexical access, but not in a gender decision task, which only requires access to the words' lemmas and not their word forms. We report two attempts to replicate this pattern, one with new materials, and one with Jescheniak and Levelt's orginal pictures. In both studies we found a strong WFE when the pictures were shown for the first time, but much weaker effects on their second and third presentation. Importantly these patterns were seen in both the picture naming and the gender decision tasks, suggesting that either word frequency does not exclusively affect word form retrieval, or that the gender decision task does not exclusively tap lemma access.

Time-course of phonetic (motor speech) encoding in utterance production

Speaking involves the preparation of the linguistic content of an utterance and of the motor programs leading to articulation. The temporal dynamics of linguistic versus motor-speech (phonetic) encoding is highly debated: phonetic encoding has been associated either to the last quarter of an utterance preparation time (∼150ms before articulation), or to virtually the entire planning time, simultaneously with linguistic encoding. We (i) review the evidence on the time-course of motor-speech encoding based on EEG/MEG event-related (ERP) studies and (ii) strive to replicate the early effects of phonological-phonetic factors in referential word production by reanalysing a large EEG/ERP dataset. The review indicates that motor-speech encoding is engaged during at least the last 300ms preceding articulation (about half of a word planning lag). By contrast, the very early involvement of phonological-phonetic factors could be replicated only partially and is not as robust as in the second half of the utterance planning time-window.

Functional architecture of executive processes: Evidence from verbal fluency and lesion mapping in stroke patients

The functional organization and related anatomy of executive functions are still largely unknown and were examined in the present study using a verbal fluency task. The objective of this study was to determine the cognitive architecture of a fluency task and related voxelwise anatomy in the GRECogVASC cohort and fMRI based meta-analytical data. First, we proposed a model of verbal fluency in which two control processes, lexico-semantic strategic search process and attention process, interact with semantic and lexico-phonological output processes. This model was assessed by testing 404 patients and 775 controls for semantic and letter fluency, naming, and processing speed (Trail Making test part A). Regression (R² = .276 and .3, P = .0001, both) and structural equation modeling (CFI: .88, RMSEA: .2, SRMR: .1) analyses supported this model. Second, voxelwise lesion-symptom mapping and disconnectome analyses demonstrated fluency to be associated with left lesions of the pars opercularis, lenticular nucleus, insula, temporopolar region, and a large number of tracts. In addition, a single dissociation showed specific association of letter fluency with the pars triangularis of F3. Disconnectome mapping showed the additional role of disconnection of left frontal gyri and thalamus. By contrast, these analyses did not identify voxels specifically associated with lexico-phonological search processes. Third, meta-analytic fMRI data (based on 72 studies) strikingly matched all structures identified by the lesion approach. These results support our modeling of the functional architecture of verbal fluency based on two control processes (strategic search and attention) operating on semantic and lexico-phonologic output processes. Multivariate analysis supports the prominent role of the temporopolar area (BA 38) in semantic fluency and the F3 triangularis area (BA 45) in letter fluency. Finally, the lack of voxels specifically dedicated to strategic search processes could be due to a distributed organization of executive functions warranting further studies.

Multiple functions of the angular gyrus at high temporal resolution

Here, the functions of the angular gyrus (AG) are evaluated in the light of current evidence from transcranial magnetic/electric stimulation (TMS/TES) and EEG/MEG studies. 65 TMS/TES and 52 EEG/MEG studies were examined in this review. TMS/TES literature points to a causal role in semantic processing, word and number processing, attention and visual search, self-guided movement, memory, and self-processing. EEG/MEG studies reported AG effects at latencies varying between 32 and 800 ms in a wide range of domains, with a high probability to detect an effect at 300-350 ms post-stimulus onset. A three-phase unifying model revolving around the process of sensemaking is then suggested: (1) early AG involvement in defining the current context, within the first 200 ms, with a bias toward the right hemisphere; (2) attention re-orientation and retrieval of relevant information within 200-500 ms; and (3) cross-modal integration at late latencies with a bias toward the left hemisphere. This sensemaking process can favour accuracy (e.g. for word and number processing) or plausibility (e.g. for comprehension and social cognition). Such functions of the AG depend on the status of other connected regions. The much-debated semantic role is also discussed as follows: (1) there is a strong TMS/TES evidence for a causal semantic role, (2) current EEG/MEG evidence is however weak, but (3) the existing arguments against a semantic role for the AG are not strong. Some outstanding questions for future research are proposed. This review recognizes that cracking the role(s) of the AG in cognition is possible only when its exact contributions within the default mode network are teased apart.

Visibility matters during wayfinding in the vertical

Visibility is the degree to which different parts of the environment can be observed from a given vantage point. In the absence of previous familiarity or signage, the visibility of key elements in a multilevel environment (e.g., the entrance, exit, or the destination itself) becomes a primary input to make wayfinding decisions and avoid getting lost. Previous research has focused on memory-based wayfinding and mental representation of 3D space, but few studies have investigated the direct effects of visibility on wayfinding. Moreover, to our knowledge, there are no studies that have explicitly observed the interaction between visibility and wayfinding under uncertainty in a multilevel environment. To bridge this gap, we studied how the visibility of destinations, as well as the continuity of sight-lines along the vertical dimension, affects unaided and goal-directed wayfinding behavior in a multilevel desktop Virtual Reality (VR) study. We obtained results from a total of 69 participants. Each participant performed a total of 24 wayfinding trials in a multilevel environment. Results showcase a significant and nonlinear correlation between the visibility of destinations and wayfinding behavioral characteristics. Specifically, once the destination was in sight, regardless of whether it was highly or barely visible, participants made an instantaneous decision to switch floors and move up towards the destination. In contrast, if the destination was out-of-sight, participants performed 'visual exploration', indicated by an increase in vertical head movements and greater time taken to switch floors. To demonstrate the direct applicability of this fundamental wayfinding behavioral pattern, we formalize these results by modeling a visibility-based cognitive agent. Our results show that by modeling the transition between exploration and exploitation as a function of visibility, cognitive agents were able to replicate human wayfinding patterns observed in the desktop VR study. This simple demonstration shows the potential of extending our main findings concerning the nonlinear relationship between visibility and wayfinding to inform the modeling of human cognition.

Behavioral and Brain Responses Highlight the Role of Usage in the Preparation of Multiword Utterances for Production

Usage-based theories assume that all aspects of language processing are shaped by the distributional properties of the language. The frequency not only of words but also of larger chunks plays a major role in language processing. These theories predict that the frequency of phrases influences the time needed to prepare these phrases for production and their acoustic duration. By contrast, dominant psycholinguistic models of utterance production predict no such effects. In these models, the system keeps track of the frequency of individual words but not of co-occurrences. This study investigates the extent to which the frequency of phrases impacts naming latencies and acoustic duration with a balanced design, where the same words are recombined to build high- and low-frequency phrases. The brain signal of participants is recorded so as to obtain information on the electrophysiological bases and functional locus of frequency effects. Forty-seven participants named pictures using high- and low-frequency adjective-noun phrases. Naming latencies were shorter for high-frequency than low-frequency phrases. There was no evidence that phrase frequency impacted acoustic duration. The electrophysiological signal differed between high- and low-frequency phrases in time windows that do not overlap with conceptualization or articulation processes. These findings suggest that phrase frequency influences the preparation of phrases for production, irrespective of the lexical properties of the constituents, and that this effect originates at least partly when speakers access and encode linguistic representations. Moreover, this study provides information on how the brain signal recorded during the preparation of utterances changes with the frequency of word combinations.

The Same Ultra-Rapid Parallel Brain Dynamics Underpin the Production and Perception of Speech

The temporal dynamics by which linguistic information becomes available is one of the key properties to understand how language is organized in the brain. An unresolved debate between different brain language models is whether words, the building blocks of language, are activated in a sequential or parallel manner. In this study, we approached this issue from a novel perspective by directly comparing the time course of word component activation in speech production versus perception. In an overt object naming task and a passive listening task, we analyzed with mixed linear models at the single-trial level the event-related brain potentials elicited by the same lexico-semantic and phonological word knowledge in the two language modalities. Results revealed that both word components manifested simultaneously as early as 75 ms after stimulus onset in production and perception; differences between the language modalities only became apparent after 300 ms of processing. The data provide evidence for ultra-rapid parallel dynamics of language processing and are interpreted within a neural assembly framework where words recruit the same integrated cell assemblies across production and perception. These word assemblies ignite early on in parallel and only later on reverberate in a behavior-specific manner.

The Role of Processing Speed and Cognitive Control on Word Retrieval in Aging and Aphasia

Purpose When speakers retrieve words, they do so extremely quickly and accurately-both speed and accuracy of word retrieval are compromised in persons with aphasia (PWA). This study examined the contribution of two domain-general mechanisms: processing speed and cognitive control on word retrieval in PWA. Method Three groups of participants, neurologically healthy young and older adults and PWA (n = 15 in each group), performed processing speed, cognitive control, lexical decision, and word retrieval tasks on a computer. The relationship between word retrieval speed and other tasks was examined for each group. Results Both aging and aphasia resulted in slower processing speed but did not affect cognitive control. Word retrieval response time delays in PWA were eliminated when processing speed was accounted for. Word retrieval speed was predicted by individual differences in cognitive control in young and older adults and additionally by processing speed in older adults. In PWA, word retrieval speed was predicted by severity of language deficit and cognitive control. Conclusions This study shows that processing speed is compromised in aphasia and could account for their slowed response times. Individual differences in cognitive control predicted word retrieval speed in healthy adults and PWA. These findings highlight the need to include nonlinguistic cognitive mechanisms in future models of word retrieval in healthy adults and word retrieval deficits in aphasia.

Morphological facilitation and semantic interference in compound production: An ERP study

This study investigates the production of nominal compounds (Experiment 1) and simple nouns (Experiment 2) in a picture-word interference (PWI) paradigm to test models of morpho-lexical representation and processing. The continuous electroencephalogram (EEG) was registered and event-related brain potentials [ERPs] were analyzed in addition to picture-naming latencies. Experiment 1 used morphologically and semantically related distractor words to tap into different pre-articulatory planning stages during compound production. Relative to unrelated distractors, naming was speeded when distractors corresponded to morphemes of the compound (sun or flower for the target sunflower), but slowed when distractors were from the same semantic category as the compound (tulip ➔ sunflower). Distractors from the same category as the compound's first constituent (moon ➔ sunflower) had no influence. The diverging effects for semantic and morphological distractors replicate results from earlier studies. ERPs revealed different effects of morphological and semantic distractors with an interesting time course: morphological effects had an earlier onset. Comparable to the naming latencies, no ERP effects were obtained for distractors from the same semantic category as the compound's first constituent. Experiment 2 investigated the effectiveness of the latter distractors, presenting them with pictures of the compounds' first constituents (e.g., moon ➔ sun). Interference was confirmed both behaviorally and in the ERPs, showing that the absence of an effect in Experiment 1 was not due to the materials used. Considering current models of speech production, the data are best explained by a cascading flow of activation throughout semantic, lexical and morpho-phonological steps of speech planning.

Word frequency effect in written production: Evidence from ERPs and neural oscillations

It has been widely documented that word frequency (WF) modulates language processing in various input and output modalities. WF effect has also been reported in the domain of written production; however, how WF affects written production is a controversial issue. The present study attempts to investigate the time course of and neural oscillation underlying the WF effect in handwritten production. Participants were asked to handwrite pictures names of high versus low WF, while concurrently recording EEG. EEG trials were extracted time-locked to picture onsets and then submitted to event-related potential analysis and time-frequency analysis. WF affected ERPs in the time windows of around 98-160 and 282-360 ms after picture onsets. More importantly, WF modulated the evoked and induced theta-band (4-8 Hz) neural oscillations in the time window of around 36-240 and 244-472 ms, respectively. Considering the time course of language production and the role of theta-band oscillation in long-term memory retrieval, we suggest that the two stages of the WF effect, respectively, reflect conceptual preparation and retrieval of orthographic word-forms in written production.

Parallel Processing of Semantics and Phonology in Spoken Production: Evidence from Blocked Cyclic Picture Naming and EEG

Spoken language production involves lexical-semantic access and phonological encoding. A theoretically important question concerns the relative time course of these two cognitive processes. The predominant view has been that semantic and phonological codes are accessed in successive stages. However, recent evidence seems difficult to reconcile with a sequential view but rather suggests that both types of codes are accessed in parallel. Here, we used ERPs combined with the "blocked cyclic naming paradigm" in which items overlapped either semantically or phonologically. Behaviorally, both semantic and phonological overlap caused interference relative to unrelated baseline conditions. Crucially, ERP data demonstrated that the semantic and phonological effects emerged at a similar latency (∼180 msec after picture onset) and within a similar time window (180-380 msec). These findings suggest that access to phonological information takes place at a relatively early stage during spoken planning, largely in parallel with semantic processing.

ERP indexes of number attraction and word order during correct verb agreement production

Successful subject-verb agreement production requires retrieving the verbal forms that agree with the features of the subject head noun and not of other nouns in the sentence. We investigate, for the first time, the electrophysiological indexes of number attraction and word order during agreement production. Twenty-four Basque native speakers were tested while producing auxiliary verbs during sentence completion of transitive sentence preambles involving singular subjects and singular or plural objects in canonical (SOV) and non-canonical (OSV) structures. ERP results yielded a larger production P2 (pP2) amplitude for mismatching than matching objects in SOV sentences, and larger negativity for OSV than SOV in number matching condition. We explain these results in terms of distinct contributions of number and word order during correct agreement production, with the pP2 indexing morphosyntactic retrieval difficulty of agreement-inflection, and the frontal negativity reflecting word order effects during monitoring the correctness of the selected verbal form.

Do bilingual children lag behind? A study of morphological encoding using ERPs

The current study investigates how bilingual children encode and produce morphologically complex words. We employed a silent-production-plus-delayed-vocalization paradigm in which event-related brain potentials (ERPs) were recorded during silent encoding of inflected words which were subsequently cued to be overtly produced. The bilingual children's spoken responses and their ERPs were compared to previous datasets from monolingual children on the same task. We found an enhanced negativity for regular relative to irregular forms during silent production in both bilingual children's languages, replicating the ERP effect previously obtained from monolingual children. Nevertheless, the bilingual children produced more morphological errors (viz. over-regularizations) than monolingual children. We conclude that mechanisms of morphological encoding (as measured by ERPs) are parallel for bilingual and monolingual children, and that the increased over-regularization rates are due to their reduced exposure to each of the two languages (relative to monolingual children).

Cortical Dynamics of Semantic Priming and Interference during Word Production: An Intracerebral Study

Language production requires that semantic representations are mapped to lexical representations on the basis of the ongoing context to select the appropriate words. This mapping is thought to generate two opposing phenomena, “semantic priming,” where multiple word candidates are activated, and “interference,” where these word activities are differentiated to make a goal-relevant selection. In previous neuroimaging and neurophysiological research, priming and interference have been associated to activity in regions of a left frontotemporal network. Most of such studies relied on recordings that either have high temporal or high spatial resolution, but not both. Here, we employed intracerebral EEG techniques to explore with both high resolutions, the neural activity associated with these phenomena. The data came from nine epileptic patients who were stereotactically implanted for presurgical diagnostics. They performed a cyclic picture-naming task contrasting semantically homogeneous and heterogeneous contexts. Of the 84 brain regions sampled, 39 showed task-evoked activity that was significant and consistent across two patients or more. In nine of these regions, activity was significantly modulated by the semantic manipulation. It was reduced for semantically homogeneous contexts (i.e., priming) in eight of these regions, located in the temporal ventral pathway as well as frontal areas. Conversely, it was increased only in the pre-SMA, notably at an early poststimulus temporal window (200–300 msec) and a preresponse temporal window (700–800 msec). These temporal effects respectively suggest the pre-SMA's role in initial conflict detection (e.g., increased response caution) and in preresponse control. Such roles of the pre-SMA are traditional from a history of neural evidence in simple perceptual tasks, yet are also consistent with recent cognitive lexicosemantic theories that highlight top–down processes in language production. Finally, although no significant semantic modulation was found in the ACC, future intracerebral EEG work should continue to inspect ACC with the pre-SMA.

Time is of the Essence: A Review of Electroencephalography (EEG) and Event-Related Brain Potentials (ERPs) in Language Research

The discovery of electroencephalography (EEG) over a century ago has changed the way we understand brain structure and function, in terms of both clinical and research applications. This paper starts with a short description of EEG and then focuses on the event-related brain potentials (ERPs), and their use in experimental settings. It describes the typical set-up of an ERP experiment. A description of a number of ERP components typically involved in language research is presented. Finally, the advantages and disadvantages of using ERPs in language research are discussed. EEG has an extensive use in today’s world, including medical, psychology, or linguistic research. The excellent temporal resolution of EEG information allows one to track a brain response in milliseconds and therefore makes it uniquely suited to research concerning language processing.

Electrophysiological characterization of facilitation and interference in the picture-word interference paradigm

The picture-word interference paradigm is often used to investigate the processes underlying word production. In this paradigm, participants name pictures while ignoring distractor words. The aim of this study is to investigate the processes underlying this task and how/when they differ from those involved in simple picture naming. It examines the electrophysiological signature of general interference (longer response times with than without distractors) and facilitation (shorter response times for distractor-word stimuli overlapping in phonemes/orthography) effects. Mass univariate analyses are used to determine the temporal boundaries and spatial distribution of these effects without a priori restrictions in the time/space dimensions. Topographic pattern analyses complement this information by indicating whether (and when) the neural networks differ across conditions. Results suggest that the general interference effect has two loci, the grammatical encoding and the phonological encoding of the target word, with different neural networks involved in the two tasks during part of the grammatical encoding process. Furthermore, the electrophysiological signature of interference and facilitation effects in the time window of phonological encoding is highly similar, suggesting that the two effects could result from the same underlying mechanism. These findings are discussed in the light of existing accounts of interference and facilitation effects.

The Timing of Utterance Planning in Task-Oriented Dialogue: Evidence from a Novel List-Completion Paradigm

In conversation, interlocutors rarely leave long gaps between turns, suggesting that next speakers begin to plan their turns while listening to the previous speaker. The present experiment used analyses of speech onset latencies and eye-movements in a task-oriented dialogue paradigm to investigate when speakers start planning their responses. German speakers heard a confederate describe sets of objects in utterances that either ended in a noun [e.g., Ich habe eine Tür und ein Fahrrad ("I have a door and a bicycle")] or a verb form [e.g., Ich habe eine Tür und ein Fahrrad besorgt ("I have gotten a door and a bicycle")], while the presence or absence of the final verb either was or was not predictable from the preceding sentence structure. In response, participants had to name any unnamed objects they could see in their own displays with utterances such as Ich habe ein Ei ("I have an egg"). The results show that speakers begin to plan their turns as soon as sufficient information is available to do so, irrespective of further incoming words.

On the time course of lexical stress priming in speech production: Behavioral and ERPs evidence from a free-stress language

The goal of the present research was to study the time course of lexical stress encoding in a free-stress language with unpredictable stress. To this aim we measured event-related brain potentials (ERPs) during lexical priming. Participants named pictures bearing either the dominant or non-dominant stress pattern, and preceded by either a congruent or an incongruent word prime (e.g., CInema-FRAgola'cinema-strawberry' vs. benZIna-FRAgola'petrol-strawberry'). Behavioral results show that participants were slower in naming targets that had the same stress pattern as the prime, and were also faster in producing words with the dominant stress pattern in the language. The electrophysiological results show that both the effects are compatible with the time course of phonological encoding in speech production. Surprisingly, a dominant stress effect occurred in the ERPs elicited by the primes, with a larger positivity for non-dominant stress words in a 150-250ms time-window. The pattern of results indicates that during speech production: a) the system is sensitive to the stress patterns distribution; b) the automatic pre-activation of a metrical frame may interfere with the phonological encoding of a to-be-uttered word.

Tracking the time course of lexical access in orthographic production: An event-related potential study of word frequency effects in written picture naming

Previous studies of spoken picture naming using event-related potentials (ERPs) have shown that speakers initiate lexical access within 200ms after stimulus onset. In the present study, we investigated the time course of lexical access in written, rather than spoken, word production. Chinese participants wrote target object names which varied in word frequency, and written naming times and ERPs were measured. Writing latencies exhibited a classical frequency effect (faster responses for high- than for low-frequency names). More importantly, ERP results revealed that electrophysiological activity elicited by high- and low frequency target names started to diverge as early as 168ms post picture onset. We conclude that lexical access during written word production is initiated within 200ms after picture onset. This estimate is compatible with previous studies on spoken production which likewise showed a rapid onset of lexical access (i.e., within 200ms after stimuli onset). We suggest that written and spoken word production share the lexicalization stage.

Specifying the role of the left prefrontal cortex in word selection

Word selection allows us to choose words during language production. This is often viewed as a competitive process wherein a lexical representation is retrieved among semantically-related alternatives. The left prefrontal cortex (LPFC) is thought to help overcome competition for word selection through top-down control. However, whether the LPFC is always necessary for word selection remains unclear. We tested 6 LPFC-injured patients and controls in two picture naming paradigms varying in terms of item repetition. Both paradigms elicited the expected semantic interference effects (SIE), reflecting interference caused by semantically-related representations in word selection. However, LPFC patients as a group showed a larger SIE than controls only in the paradigm involving item repetition. We argue that item repetition increases interference caused by semantically-related alternatives, resulting in increased LPFC-dependent cognitive control demands. The remaining network of brain regions associated with word selection appears to be sufficient when items are not repeated.

Serial order in word form retrieval: New insights from the auditory picture-word interference task

One important theoretical question about word production concerns whether the phonemes of a word are retrieved in parallel or in sequential order. To address this question, Meyer and Schriefers (Journal of Experimental Psychology: Learning, Memory, and Cognition 17:1146-1160, 1991) used an auditory picture-word interference task and manipulated the position of the phonemes shared between a distractor word and a target picture. They found that begin-related distractors (e.g., boat-bone) facilitated naming times when they were presented within 150 ms before or after the picture, whereas end-related distractors (e.g., cone-bone) were effective only if presented within 150 ms after the picture. This suggested that the word's end phonemes were activated later than the beginning ones. However, it remained unclear whether these effects genuinely reflected facilitation at the level of phonological retrieval. In this study, we examined later distractor presentation onsets, so that the distractors had little opportunity to influence earlier, lexical selection processes. At the latest onset tested, end-related-but not begin-related-distractors significantly facilitated naming. We concluded that late-presented distractors do indeed influence phonological encoding, and that their asymmetric effects support a sequential model of phoneme retrieval.

Early and Late Electrophysiological Effects of Distractor Frequency in Picture Naming: Reconciling Input and Output Accounts

The "distractor-frequency effect" refers to the finding that high-frequency (HF) distractor words slow picture naming less than low-frequency distractors in the picture-word interference paradigm. Rival input and output accounts of this effect have been proposed. The former attributes the effect to attentional selection mechanisms operating during distractor recognition, whereas the latter attributes it to monitoring/decision mechanisms operating on distractor and target responses in an articulatory buffer. Using high-density (128-channel) EEG, we tested hypotheses from these rival accounts. In addition to conducting stimulus- and response-locked whole-brain corrected analyses, we investigated the correct-related negativity, an ERP observed on correct trials at fronto-central electrodes proposed to reflect the involvement of domain general monitoring. The whole-brain ERP analysis revealed a significant effect of distractor frequency at inferior right frontal and temporal sites between 100 and 300-msec post-stimulus onset, during which lexical access is thought to occur. Response-locked, region of interest (ROI) analyses of fronto-central electrodes revealed a correct-related negativity starting 121 msec before and peaking 125 msec after vocal onset on the grand averages. Slope analysis of this component revealed a significant difference between HF and low-frequency distractor words, with the former associated with a steeper slope on the time window spanning from 100 msec before to 100 msec after vocal onset. The finding of ERP effects in time windows and components corresponding to both lexical processing and monitoring suggests the distractor frequency effect is most likely associated with more than one physiological mechanism.

Seriality of semantic and phonological processes during overt speech in Mandarin as revealed by event-related brain potentials

How is information transmitted across semantic and phonological levels in spoken word production? Recent evidence from speakers of Western languages such as English and Dutch suggests non-discrete transmission, but it is not clear whether this view can be generalized to other languages such as Mandarin, given potential differences in phonological encoding across languages. The present study used Mandarin speakers and combined a behavioral picture-word interference task with event-related potentials. The design factorially crossed semantic and phonological relatedness. Results showed semantic and phonological effects both in behavioral and electrophysiological measurements, with statistical additivity in latencies, and discrete time signatures (250-450 ms and 450-600 ms after picture onset for the semantic and phonological condition, respectively). Overall, results suggest that in Mandarin spoken production, information is transmitted from semantic to phonological levels in a sequential fashion. Hence, temporal signatures associated with spoken word production might differ depending on target language.

Seeing the same words differently: the time course of automaticity and top-down intention in reading

We investigated how linguistic intention affects the time course of visual word recognition by comparing the brain's electrophysiological response to a word's lexical frequency, a well-established psycholinguistic marker of lexical access, when participants actively retrieve the meaning of the written input (semantic categorization) versus a situation where no language processing is necessary (ink color categorization). In the semantic task, the ERPs elicited by high-frequency words started to diverge from those elicited by low-frequency words as early as 120 msec after stimulus onset. On the other hand, when categorizing the colored font of the very same words in the color task, word frequency did not modulate ERPs until some 100 msec later (220 msec poststimulus onset) and did so for a shorter period and with a smaller scalp distribution. The results demonstrate that, although written words indeed elicit automatic recognition processes in the brain, the speed and quality of lexical processing critically depends on the top-down intention to engage in a linguistic task.

Producing morphologically complex words: an ERP study with children and adults

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ERPs are used to investigate the production of plurals-inside-compounds in children and adults.

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Results revealed a highly specific brain response to a subtle linguistic contrast.

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Distribution of ERPs differs between adults and children.

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Brain networks involved in language production are subject to developmental changes.

A widely studied morphological phenomenon in psycholinguistic research is the plurals-inside-compounds effect in English, which is the avoidance of regular plural modifiers within compounds (e.g., *rats hunter). The current study employs event-related brain potentials (ERPs) to investigate the production of plurals-inside-compounds in children and adults. We specifically examined the ERP correlates of producing morphologically complex words in 8-year-olds, 12-year-olds and adults, by recording ERPs during the silent production of compounds with plural or singular modifiers. Results for both children and adults revealed a negativity in response to compounds produced from regular plural forms when compared to compounds formed from irregular plurals, indicating a highly specific brain response to a subtle linguistic contrast. Although children performed behaviourally with an adult-like pattern in the task, we found a broader distribution and a considerably later latency in children's brain potentials than in adults’, indicating that even in late childhood the brain networks involved in language processing are subject to subtle developmental changes.

ERP correlates of word production predictors in picture naming: a trial by trial multiple regression analysis from stimulus onset to response

A major effort in cognitive neuroscience of language is to define the temporal and spatial characteristics of the core cognitive processes involved in word production. One approach consists in studying the effects of linguistic and pre-linguistic variables in picture naming tasks. So far, studies have analyzed event-related potentials (ERPs) during word production by examining one or two variables with factorial designs. Here we extended this approach by investigating simultaneously the effects of multiple theoretical relevant predictors in a picture naming task. High density EEG was recorded on 31 participants during overt naming of 100 pictures. ERPs were extracted on a trial by trial basis from picture onset to 100 ms before the onset of articulation. Mixed-effects regression models were conducted to examine which variables affected production latencies and the duration of periods of stable electrophysiological patterns (topographic maps). Results revealed an effect of a pre-linguistic variable, visual complexity, on an early period of stable electric field at scalp, from 140 to 180 ms after picture presentation, a result consistent with the proposal that this time period is associated with visual object recognition processes. Three other variables, word Age of Acquisition, Name Agreement, and Image Agreement influenced response latencies and modulated ERPs from ~380 ms to the end of the analyzed period. These results demonstrate that a topographic analysis fitted into the single trial ERPs and covering the entire processing period allows one to associate the cost generated by psycholinguistic variables to the duration of specific stable electrophysiological processes and to pinpoint the precise time-course of multiple word production predictors at once.

Effects of navigated TMS on object and action naming

Transcranial magnetic stimulation (TMS) has been used to induce speech disturbances and to affect speech performance during different naming tasks. Lately, repetitive navigated TMS (nTMS) has been used for non-invasive mapping of cortical speech-related areas. Different naming tasks may give different information that can be useful for presurgical evaluation. We studied the sensitivity of object and action naming tasks to nTMS and compared the distributions of cortical sites where nTMS produced naming errors. Eight healthy subjects named pictures of objects and actions during repetitive nTMS delivered to semi-random left-hemispheric sites. Subject-validated image stacks were obtained in the baseline naming of all pictures before nTMS. Thereafter, nTMS pulse trains were delivered while the subjects were naming the images of objects or actions. The sessions were video-recorded for offline analysis. Naming during nTMS was compared with the baseline performance. The nTMS-induced naming errors were categorized by error type and location. nTMS produced no-response errors, phonological paraphasias, and semantic paraphasias. In seven out of eight subjects, nTMS produced more errors during object than action naming. Both intrasubject and intersubject analysis showed that object naming was significantly more sensitive to nTMS. When the number of errors was compared according to a given area, nTMS to postcentral gyrus induced more errors during object than action naming. Object naming is apparently more easily disrupted by TMS than action naming. Different stimulus types can be useful for locating different aspects of speech functions. This provides new possibilities in both basic and clinical research of cortical speech representations.

Exploring the multiple-level hypothesis of AoA effects in spoken and written object naming using a topographic ERP analysis

Here we tested the multiple-loci hypothesis of age-of-acquisition effects in both spoken and handwritten object naming using Event-Related Potentials (ERPs) and spatiotemporal segmentation analysis. Participants had to say aloud or write down picture names that varied on frequency trajectory (age-of-acquisition). Early-acquired words yielded shorter naming times than late-acquired words in both spoken and written naming. More importantly, AoA modulated ERPs only during a later time-window in both output modalities: waveforms started to diverge around 400 ms, which corresponded to the end of a period of topographic stability starting at around 260 ms in both conditions. These stable electrophysiological maps lasted longer in the late than in the early-acquired condition and shifted the onset of the following periods of stable electrophysiological activity. Taken together, the findings are at odds with the multiple loci hypothesis, but support the hypothesis that AoA affects a single encoding level, namely the word-form encoding process.

Tracking the time course of multi-word noun phrase production with ERPs or on when (and why) cat is faster than the big cat

Words are rarely produced in isolation. Yet, our understanding of multi-word production, and especially its time course, is still rather poor. In this research, we use event-related potentials to examine the production of multi-word noun phrases in the context of overt picture naming. We track the processing costs associated with the production of these noun phrases as compared with the production of bare nouns, from picture onset to articulation. Behavioral results revealed longer naming latencies for French noun phrases with determiners and pre-nominal adjectives (D-A-N, the big cat) than for noun phrases with a determiner (D-N, the cat), or bare nouns (N, cat). The spatio-temporal analysis of the ERPs revealed differences in the duration of stable global electrophysiological patterns as a function of utterance format in two time windows, from ~190 to 300 ms after picture onset, and from ~530 ms after picture onset to 100 ms before articulation. These findings can be accommodated in the following model. During grammatical encoding (here from ~190 to 300 ms), the noun and adjective lemmas are accessed in parallel, followed by the selection of the gender-agreeing determiner. Phonological encoding (after ~530 ms) operates sequentially. As a consequence, the phonological encoding process is longer for longer utterances. In addition, when determiners are repeated across trials, their phonological encoding can be anticipated or primed, resulting in a shortened encoding process.

Distinct patterns of brain activity characterise lexical activation and competition in spoken word production

According to a prominent theory of language production, concepts activate multiple associated words in memory, which enter into competition for selection. However, only a few electrophysiological studies have identified brain responses reflecting competition. Here, we report a magnetoencephalography study in which the activation of competing words was manipulated by presenting pictures (e.g., dog) with distractor words. The distractor and picture name were semantically related (cat), unrelated (pin), or identical (dog). Related distractors are stronger competitors to the picture name because they receive additional activation from the picture relative to other distractors. Picture naming times were longer with related than unrelated and identical distractors. Phase-locked and non-phase-locked activity were distinct but temporally related. Phase-locked activity in left temporal cortex, peaking at 400 ms, was larger on unrelated than related and identical trials, suggesting differential activation of alternative words by the picture-word stimuli. Non-phase-locked activity between roughly 350-650 ms (4-10 Hz) in left superior frontal gyrus was larger on related than unrelated and identical trials, suggesting differential resolution of the competition among the alternatives, as reflected in the naming times. These findings characterise distinct patterns of activity associated with lexical activation and competition, supporting the theory that words are selected by competition.

When does word frequency influence written production?

The aim of the present study was to explore the central (e.g., lexical processing) and peripheral processes (motor preparation and execution) underlying word production during typewriting. To do so, we tested non-professional typers in a picture typing task while continuously recording EEG. Participants were instructed to write (by means of a standard keyboard) the corresponding name for a given picture. The lexical frequency of the words was manipulated: half of the picture names were of high-frequency while the remaining were of low-frequency. Different measures were obtained: (1) first keystroke latency and (2) keystroke latency of the subsequent letters and duration of the word. Moreover, ERPs locked to the onset of the picture presentation were analyzed to explore the temporal course of word frequency in typewriting. The results showed an effect of word frequency for the first keystroke latency but not for the duration of the word or the speed to which letter were typed (interstroke intervals). The electrophysiological results showed the expected ERP frequency effect at posterior sites: amplitudes for low-frequency words were more positive than those for high-frequency words. However, relative to previous evidence in the spoken modality, the frequency effect appeared in a later time-window. These results demonstrate two marked differences in the processing dynamics underpinning typing compared to speaking: First, central processing dynamics between speaking and typing differ already in the manner that words are accessed; second, central processing differences in typing, unlike speaking, do not cascade to peripheral processes involved in response execution.

The temporal dynamics of first versus second language production

In this study we explored the temporal origin of processing differences between first and second language production. Forty highly proficient bilinguals named objects of high and low lexical frequency aloud for both L1 and L2 separately while event-related brain potentials (ERPs) were recorded. The first electrophysiological differences elicited by response language occurred at the same early P2 peak (∼140-220 ms) where we observed the onset of the lexical frequency effect, but only for those bilinguals who started naming in an L1 context and afterwards switched to an L2 naming context. The bilinguals who named objects in the reverse direction did not display a language effect in the ERPs. Taken together, the data show that the L2 naming disadvantage originates during the onset of lexical access and seems to be driven by both representational strength, which is lower for L2 words, and language control demands, which are higher for L2 words.

The poor helping the rich: How can incomplete representations monitor complete ones?

Pickering & Garrod (P&G) propose that inner speech monitoring is subserved by predictions stemming from fast forward modeling. In this commentary, we question this alignment of language prediction with the inner speech monitor. We wonder how the speech monitor can function so efficiently if it is based on incomplete representations.

A late locus of the distractor frequency effect in picture-word interference: evidence from event-related potentials

In this study, we investigated how people deal with irrelevant contextual information during speech production. Two main models have been proposed. WEAVER++ assumes that irrelevant information is removed from the production system by an early blocking mechanism. On the other hand, the response exclusion hypothesis assumes a blocking mechanism that operates late, after lexical selection has finished. To delineate between these models, we focused on the distractor frequency effect (i.e., longer picture naming latencies in the context of low-frequency compared to high-frequency words) and measured ERPs concurrently. Behaviorally, the distractor frequency effect was replicated. In the ERPs, three effects were found. One effect occurred very early and is interpreted as an effect of low-level visual feature processing. The two other effects occurred after lexical access and are thus in line with the response exclusion hypothesis.