Is comprehension necessary for error detection? A conflict-based account of monitoring in speech production

The role of conflict, feedback, and action comprehension in monitoring of action errors: Evidence for internal and external routes

The mechanisms and brain regions underlying error monitoring in complex action are poorly understood, yet errors and impaired error correction in these tasks are hallmarks of apraxia, a common disorder associated with left hemisphere stroke. Accounts of monitoring of language posit an internal route by which production planning or competition between candidate representations provide predictive signals that monitoring is required to prevent error, and an external route in which output is monitored using the comprehension system. Abnormal reliance on the external route has been associated with damage to brain regions critical for sensory-motor transformation and a pattern of gradual error 'clean-up' called conduite d'approche (CD). Action pantomime data from 67 participants with left hemisphere stroke were consistent with versions of internal route theories positing that competition signals monitoring requirements. Support Vector Regression Lesion Symptom Mapping (SVR-LSM) showed that lesions in the inferior parietal, posterior temporal, and arcuate fasciculus/superior longitudinal fasciculus predicted action conduite d'approche, overlapping the regions previously observed in the language domain. A second experiment with 12 patients who produced substantial action CD assessed whether factors impacting the internal route (action production ability, competition) versus external route (vision of produced actions, action comprehension) influenced correction attempts. In these 'high CD' patients, vision of produced actions and integrity of gesture comprehension interacted to determine successful error correction, supporting external route theories. Viewed together, these and other data suggest that skilled actions are monitored both by an internal route in which conflict aids in detection and correction of errors during production planning, and an external route that detects mismatches between produced actions and stored knowledge of action appearance. The parallels between language and action monitoring mechanisms and neuroanatomical networks pave the way for further exploration of common and distinct processes across these domains.

The dual origin of semantic errors in access deficit: activation vs. inhibition deficit

According to most models of language production, to name a picture one must first map semantic features onto lexical items. Even if both sets of representations are intact, problems in mapping semantic to lexical representations can impair production. Individuals with this problem, sometimes referred to as "access deficit", often demonstrate evidence of preserved semantic knowledge (e.g., good comprehension), increased rate of lexical (usually semantic) errors in production, and inconsistent accuracy on naming the same picture on different occasions. In this paper, I argue that access deficit can have two distinct etiologies. I will present a case of double dissociation between two individuals with chronic post-stroke aphasia, one of whom shows a profile compatible with impaired activation of the target lexical item from semantic features (activation deficit), while the other shows a profile compatible with impaired inhibition of competing lexical items (inhibition deficit). These results have three key implications: (a) they provide support for the theoretical separation between activation and selection processes in computational models of word production, (b) they point to the critical role of inhibitory control in lexical selection, and (c) they invite a closer inspection of the origin of semantic errors in individuals with access deficit in order to choose the best treatment option.

The Subjective Experience of Inner Speech in Aphasia Is a Meaningful Reflection of Lexical Retrieval

Purpose Individuals with aphasia often report that they feel able to say words in their heads, regardless of speech output ability. Here, we examine whether these subjective reports of successful "inner speech" (IS) are meaningful and test the hypothesis that they reflect lexical retrieval. Method Participants were 53 individuals with chronic aphasia. During silent picture naming, participants reported whether or not they could say the name of each item inside their heads. Using the same items, they also completed 3 picture-based tasks that required phonological retrieval and 3 matched auditory tasks that did not. We compared participants' performance on these tasks for items they reported being able to say internally versus those they reported being unable to say internally. Then, we examined the relationship of psycholinguistic word features to self-reported IS and spoken naming accuracy. Results Twenty-six participants reported successful IS on nearly all items, so they could not be included in the item-level analyses. These individuals performed correspondingly better than the remaining participants on tasks requiring phonological retrieval, but not on most other language measures. In the remaining group ( n = 27), IS reports related item-wise to performance on tasks requiring phonological retrieval, but not to matched control tasks. Additionally, IS reports were related to 3 word characteristics associated with lexical retrieval, but not to articulatory complexity; spoken naming accuracy related to all 4 word characteristics. Six participants demonstrated evidence of unreliable IS reporting; compared with the group, they also detected fewer errors in their spoken responses and showed more severe language impairments overall. Conclusions Self-reported IS is meaningful in many individuals with aphasia and reflects lexical phonological retrieval. These findings have potential implications for treatment planning in aphasia and for our understanding of IS in the general population.

The role of working memory for syntactic formulation in language production

Four picture-description experiments investigated if syntactic formulation in language production can proceed with only minimal working memory involvement. Experiments 1-3 compared the initiation latencies, utterance durations, and errors for syntactically simpler picture descriptions (adjective-noun phrases, e.g., the red book) to those of more complex descriptions (relative clauses, e.g., the book that is red). In Experiment 4, the syntactically more complex descriptions were also lexically more complex (e.g., the book and the car vs. the book). Simpler and more complex descriptions were produced under verbal memory load consisting of 2 or 4 unrelated nouns, or under no load. Across experiments, load actually made production more efficient (as manifested in shorter latencies, shorter durations or both), and sped up the durations of relative clauses more than those of adjective-noun phrases. The only evidence for disproportional disruption of more complex descriptions by load was a greater increase of production errors for these descriptions than for simpler descriptions under load in Experiments 2 and 4. We thus conclude that syntactic formulation in production (for certain constructions or in certain situations) can proceed with minimal working memory involvement. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Monitoring of language selection errors in switching: Not all about conflict

Although bilingual speakers are very good at selectively using one language rather than another, sometimes language selection errors occur. To investigate how bilinguals monitor their speech errors and control their languages in use, we recorded event-related potentials (ERPs) in unbalanced Dutch-English bilingual speakers in a cued language-switching task. We tested the conflict-based monitoring model of Nozari and colleagues by investigating the error-related negativity (ERN) and comparing the effects of the two switching directions (i.e., to the first language, L1 vs. to the second language, L2). Results show that the speakers made more language selection errors when switching from their L2 to the L1 than vice versa. In the EEG, we observed a robust ERN effect following language selection errors compared to correct responses, reflecting monitoring of speech errors. Most interestingly, the ERN effect was enlarged when the speakers were switching to their L2 (less conflict) compared to switching to the L1 (more conflict). Our findings do not support the conflict-based monitoring model. We discuss an alternative account in terms of error prediction and reinforcement learning.

Age-related effects in compound production: Evidence from a double-object picture naming task

This study investigated effects of healthy ageing and of non-verbal attentional control on speech production. Young and older speakers participated in a picture-word interference (PWI) task with compound targets. To increase the processing load, the two pictures of the compounds’ constituents were presented side-by-side for spoken naming (e.g., a picture of a sun + a picture of a flower to be named with sunflower). Written distractors either corresponded to the first or second constituent ( sun or flower → sunflower), or were semantically related either to the first constituent of the target ( moon → sunflower) or to the second constituent/whole word ( tulip → sunflower). Morpho-phonological facilitation was obtained for both constituents, whereas semantic interference was restricted to first-constituent-related semantic distractors. Furthermore, a trend towards facilitation was obtained for distractors that were semantically related to the whole word. Older speakers were slower and produced more errors than young speakers. While morphological effects of first-constituent distractors were stronger for the elderly, the semantic effects were not affected by age. Non-verbal attentional control processes, measured in the Simon task, significantly contributed to morpho-phonological priming in the elderly, but they did not affect semantic interference or semantic facilitation. With a picture naming task that increases the semantic and lexical processing load, we corroborate earlier evidence that word-finding difficulties in the elderly result from deficient phonological encoding, whereas lexical-semantic and morpho-phonological representations remain stable with age.

Age-related effects in compound production: Intact lexical representations but more effortful encoding

The production of nominal compounds in the presence of morphological, semantic, and unrelated distractor words (picture-word interference paradigm) was investigated in young (M = 27 years) and older (M = 70.5 years) German speakers to test models of speech production and lexical representation. Constituent distractors of compound targets (lip or stick for the target LIPSTICK) speeded compound naming, while naming was slowed by distractors that were categorically related to the compound as a whole (powder → LIPSTICK). Furthermore, no effects were obtained for distractors from the same category as the first constituent of compound targets in picture-naming latencies (toe → LIPSTICK). These effects were present in both age groups and indicate that compounds are stored holistically at the lemma level, and as morphemes at the word-form level, unaffected by age. Main effects of age revealed overall slower picture naming and less accurate responses in the elderly. Furthermore, older speakers showed stronger morphological facilitation, while semantic distractor effects were unaffected by age. In a non-verbal attentional control task (Simon task), older speakers were slower overall and showed larger processing costs than young speakers in the conflict (incongruent) condition. Our data replicate a decline in non-verbal attentional control with age and also reveal slower and more error-prone picture-naming in the elderly. These language-specific changes, however, seem to be independent from attentional control and are likely to result from less fluent morpho-phonological encoding in the elderly.

Monitoring speech production and comprehension: Where is the second-language delay?

Research on error monitoring suggests that bilingual Dutch-English speakers are slower to correct some speech errors in their second language (L2) as opposed to their first language (L1). But which component of self-monitoring is slowed down in L2, error detection or interruption and repair of the error? This study charted the time course of monitoring in monolingual English speakers and bilingual Dutch-English speakers in language production and language comprehension, with the aim of pinpointing the component(s) of monitoring that cause an L2 disadvantage. First, we asked whether phonological errors are interrupted more slowly in L2. An analysis of data from three speech error elicitation experiments indeed showed that Dutch-English bilinguals were slower to stop speaking after an error had been detected in their L2 (English) than in their L1 (Dutch), at least for interrupted errors. A similar L2 disadvantage was found when comparing the L2 of Dutch-English bilinguals to the L1 of English monolinguals. Second, monolingual English speakers and bilingual Dutch-English speakers performed a picture naming task, a production monitoring task, and a comprehension monitoring task. Bilingual English speakers were slower in naming pictures in their L2 than monolingual English speakers. However, the production monitoring task and comprehension monitoring task yielded comparable response latencies between monolinguals in their L1 and bilinguals in their L2, indicating that monitoring processes in L2 are not generally slower. We suggest that interruption and repair are planned concurrently and that the difficulty of repairing in L2 triggers a slow-down in L2 interruption.

Task difficulty modulates brain-behavior correlations in language production and cognitive control: Behavioral and fMRI evidence from a phonological go/no-go picture-naming paradigm

Language production and cognitive control are complex processes that involve distinct yet interacting brain networks. However, the extent to which these processes interact and their neural bases have not been thoroughly examined. Here, we investigated the neural and behavioral bases of language production and cognitive control via a phonological go/no-go picture-naming task. Naming difficulty and cognitive control demands (i.e., conflict monitoring and response inhibition) were manipulated by varying the proportion of naming trials (go trials) and inhibition trials (no-go trials) across task runs. The results demonstrated that as task demands increased, participants' behavioral performance declined (i.e., longer reaction times on naming trials, more commission errors on inhibition trials) whereas brain activation generally increased. Increased activation was found not only within the language network but also in domain-general control regions. Additionally, right superior and inferior frontal and left supramarginal gyri were sensitive to increased task difficulty during both language production and response inhibition. We also found both positive and negative brain-behavior correlations. Most notably, increased activation in sensorimotor regions, such as precentral and postcentral gyri, was associated with better behavioral performance, in both successful picture naming and successful inhibition. Moreover, comparing the strength of correlations across conditions indicated that the brain-behavior correlations in sensorimotor regions that were associated with improved performance became stronger as task demands increased. Overall, our results suggest that cognitive control demands affect language production, and that successfully coping with increases in task difficulty relies on both language-specific and domain-general cognitive control regions.

Language switching decomposed through MEG and evidence from bimodal bilinguals

A defining feature of human cognition is the ability to quickly and accurately alternate between complex behaviors. One striking example of such an ability is bilinguals' capacity to rapidly switch between languages. This switching process minimally comprises disengagement from the previous language and engagement in a new language. Previous studies have associated language switching with increased prefrontal activity. However, it is unknown how the subcomputations of language switching individually contribute to these activities, because few natural situations enable full separation of disengagement and engagement processes during switching. We recorded magnetoencephalography (MEG) from American Sign Language-English bilinguals who often sign and speak simultaneously, which allows to dissociate engagement and disengagement. MEG data showed that turning a language "off" (switching from simultaneous to single language production) led to increased activity in the anterior cingulate cortex (ACC) and dorsolateral prefrontal cortex (dlPFC), while turning a language "on" (switching from one language to two simultaneously) did not. The distinct representational nature of these on and off processes was also supported by multivariate decoding analyses. Additionally, Granger causality analyses revealed that (i) compared with "turning on" a language, "turning off" required stronger connectivity between left and right dlPFC, and (ii) dlPFC activity predicted ACC activity, consistent with models in which the dlPFC is a top-down modulator of the ACC. These results suggest that the burden of language switching lies in disengagement from the previous language as opposed to engaging a new language and that, in the absence of motor constraints, producing two languages simultaneously is not necessarily more cognitively costly than producing one.

To select or to wait? The importance of criterion setting in debates of competitive lexical selection

Competitive accounts of lexical selection propose that the activation of competitors slows down the selection of the target. Non-competitive accounts, on the other hand, posit that target response latencies are independent of the activation of competing items. In this paper, we propose a signal detection framework for lexical selection and show how a flexible selection criterion affects claims of competitive selection. Specifically, we review evidence from neurotypical and brain-damaged speakers and demonstrate that task goals and the state of the production system determine whether a competitive or a non-competitive selection profile arises. We end by arguing that there is conclusive evidence for a flexible criterion in lexical selection, and that integrating criterion shifts into models of language production is critical for evaluating theoretical claims regarding (non-)competitive selection.

Phonological regularity, perceptual biases, and the role of phonotactics in speech error analysis

Speech errors involving manipulations of sounds tend to be phonologically regular in the sense that they obey the phonotactic rules of well-formed words. We review the empirical evidence for phonological regularity in prior research, including both categorical assessments of words and regularity at the granular level involving specific segments and contexts. Since the reporting of regularity is affected by human perceptual biases, we also document this regularity in a new data set of 2,228 sublexical errors that was collected using methods that are demonstrably less prone to bias. These facts validate the claim that sound errors are overwhelmingly regular, but the new evidence suggests speech errors admit more phonologically ill-formed words than previously thought. Detailed facts of the phonological structure of errors, including this revised standard, are then related to model assumptions in contemporary theories of phonological encoding. This article is categorized under: Linguistics > Linguistic Theory Linguistics > Computational Models of Language Psychology > Language.

Is adaptive control in language production mediated by learning?

Recent work using the Picture Word Interference (PWI) paradigm has revealed that language production, similar to non-verbal tasks, shows a robust Congruency Sequence Effect (CSE), defined as a decreased congruency effect following incongruent trials. Although CSE is considered an index of adaptive control, its mechanism is debated. In two experiments, we tested the predictions of a learning model of adaptive control in production, using a task-switching paradigm fully balanced to evaluate CSE on a PWI trial as a function of the congruency of a 2-back PWI trial (within-task CSE), as well as a 1-back trial belonging to a different task (cross-task CSE). The second task was a visuospatial task with congruent and incongruent trials in Experiment 1, and a self-paced reading task with ambiguous and unambiguous sentences in Experiment 2 that imposed a gap between the two PWI trials twice as long of that in Experiment 1. A learning model posits that CSE is the result of changes to the connection weights between task-specific representations and a control center, which leads to two predictions in our paradigm: (a) a robust within-task CSE unaffected by the intervening trial and the gap duration, and (b) an absent or reversed cross-task CSE. These predictions were contrasted with two versions of an activation model of CSE. In accord with the predictions of the learning model, we found robust within-task CSE in PWI in both Experiments with a comparable effect size. Similarly, evidence of within-task CSE was also found in the visuospatial and sentence reading tasks. On the other hand, examination of cross-task CSE from PWI to the other tasks and vice versa revealed either absent or reversed CSE. Collectively, these results support a learning model of adaptive control in language production.

Uniqueness Point Effects during Speech Planning in Adults Who Do and Do Not Stutter

BACKGROUND/AIMS

Previous studies employing a variety of tasks have demonstrated that adults who stutter (AWS) pre-sent with phonological encoding differences compared to adults who do not stutter (AWNS). The present study examined whether atypical preverbal monitoring also influenced AWS performance during one such paradigm - the silent phoneme monitoring task. Specifically, we investigated whether monitoring latencies for AWS were accelerated after the word's uniqueness point - the phoneme that isolates the word from all lexical competitors - as observed for AWNS when monitoring internal and external speech.

METHODS

Twenty adults (10 AWS, 10 AWNS) completed a silent phoneme monitoring task using stimuli which contained either (a) early uniqueness points (EUP), (b) late uniqueness points, or (c) no uniqueness point (NUP). Response latency when identifying word-final phonemes was measured.

RESULTS

AWNS exhibited the expected uniqueness point effect when monitoring internal speech; word-final phonemes were accessed more rapidly for words with EUP than NUP. In contrast, AWS did not differ in the phoneme monitoring speed. That is, AWS did not exhibit the expected uniqueness point effects.

CONCLUSION

Findings suggest that inefficient or atypical preverbal monitoring may be present in AWS and support theories that implicate the internal speech monitor as an area of deficit.

Monitoring and Control in Language Production

Language research has provided insight into how speakers translate a thought into a sequence of sounds that ultimately becomes words, phrases, and sentences. Despite the complex stages involved in this process, relatively little is known about how we avoid and handle production and comprehension errors that would otherwise impede communication. We review current research on the mechanisms underlying monitoring and control of the language system, especially production, with particular emphasis on whether such monitoring is issued by domain-general or domain-specific procedures.

Verbal monitoring in Parkinson's disease: A comparison between internal and external monitoring

Patients with Parkinson's disease (PD) display a variety of impairments in motor and non-motor language processes; speech is decreased on motor aspects such as amplitude, prosody and speed and on linguistic aspects including grammar and fluency. Here we investigated whether verbal monitoring is impaired and what the relative contributions of the internal and external monitoring route are on verbal monitoring in patients with PD relative to controls. Furthermore, the data were used to investigate whether internal monitoring performance could be predicted by internal speech perception tasks, as perception based monitoring theories assume. Performance of 18 patients with Parkinson's disease was measured on two cognitive performance tasks and a battery of 11 linguistic tasks, including tasks that measured performance on internal and external monitoring. Results were compared with those of 16 age-matched healthy controls. PD patients and controls generally performed similarly on the linguistic and monitoring measures. However, we observed qualitative differences in the effects of noise masking on monitoring and disfluencies and in the extent to which the linguistic tasks predicted monitoring behavior. We suggest that the patients differ from healthy subjects in their recruitment of monitoring channels.

Investigating the origin of nonfluency in aphasia: A path modeling approach to neuropsychology

A major challenge in understanding the origin of clinical symptoms in neuropsychological impairments is capturing the complexity of the underlying cognitive structure. This paper presents a practical guide to path modeling, a statistical approach that is well-suited for modeling multivariate outcomes with a multi-factorial origin. We discuss a step-by-step application of such a model to the problem of nonfluency in aphasia. Individuals with aphasia are often classified into fluent and nonfluent groups for both clinical and research purposes, but despite a large body of research on the topic, the origin of nonfluency remains obscure. We propose a model of nonfluency inspired by the psycholinguistic approach to sentence production, review several bodies of work that have independently suggested a relationship between fluency and various elements in this model, and implement it using path modeling on data from 112 individuals with aphasia from the AphasiaBank. The results show that word production, comprehension, and working memory deficits all contribute to nonfluency, in addition to syntactic impairment which has a strong and direct impact on fluency. More generally, we demonstrate that a path model is an excellent tool for exploring complex neuropsychological symptoms such as nonfluency.

Identification and Remediation of Phonological and Motor Errors in Acquired Sound Production Impairment

Purpose

This study aimed to test whether an approach to distinguishing errors arising in phonological processing from those arising in motor planning also predicts the extent to which repetition-based training can lead to improved production of difficult sound sequences.

Method

Four individuals with acquired speech production impairment who produced consonant cluster errors involving deletion were examined using a repetition task. We compared the acoustic details of productions with deletion errors in target consonant clusters to singleton consonants. Changes in accuracy over the course of the study were also compared.

Results

Two individuals produced deletion errors consistent with a phonological locus of the errors, and 2 individuals produced errors consistent with a motoric locus of the errors. The 2 individuals who made phonologically driven errors showed no change in performance on a repetition training task, whereas the 2 individuals with motoric errors improved in their production of both trained and untrained items.

Conclusions

The results extend previous findings about a metric for identifying the source of sound production errors in individuals with both apraxia of speech and aphasia. In particular, this work may provide a tool for identifying predominant error types in individuals with complex deficits.

Form Overrides Meaning When Bilinguals Monitor for Errors

Bilinguals rarely produce unintended language switches, which may in part be because switches are detected and corrected by an internal monitor. But are language switches easier or harder to detect than within-language semantic errors? To approximate internal monitoring, bilinguals listened (Experiment 1) or read aloud (Experiment 2) stories, and detected language switches (translation equivalents or semantically unrelated to expected words) and within-language errors (semantically related or unrelated to expected words). Bilinguals detected semantically related within-language errors most slowly and least accurately, language switches more quickly and accurately than within-language errors, and (in Experiment 2), translation equivalents as quickly and accurately as unrelated language switches. These results suggest that internal monitoring of form (which can detect mismatches in language membership) completes earlier than, and is independent of, monitoring of meaning. However, analysis of reading times prior to error detection revealed meaning violations to be more disruptive for processing than language violations.

The timing of spontaneous detection and repair of naming errors in aphasia

This study examined the timing of spontaneous self-monitoring in the naming responses of people with aphasia. Twelve people with aphasia completed a 615-item naming test twice, in separate sessions. Naming attempts were scored for accuracy and error type, and verbalizations indicating detection were coded as negation (e.g., "no, not that") or repair attempts (i.e., a changed naming attempt). Focusing on phonological and semantic errors, we measured the timing of the errors and of the utterances that provided evidence of detection. The effects of error type and detection response type on error-to-detection latencies were analyzed using mixed-effects regression modeling. We first asked whether phonological errors and semantic errors differed in the timing of the detection process or repair planning. Results suggested that the two error types primarily differed with respect to repair planning. Specifically, repair attempts for phonological errors were initiated more quickly than repair attempts for semantic errors. We next asked whether this difference between the error types could be attributed to the tendency for phonological errors to have a high degree of phonological similarity with the subsequent repair attempts, thereby speeding the programming of the repairs. Results showed that greater phonological similarity between the error and the repair was associated with faster repair times for both error types, providing evidence of error-to-repair priming in spontaneous self-monitoring. When controlling for phonological overlap, significant effects of error type and repair accuracy on repair times were also found. These effects indicated that correct repairs of phonological errors were initiated particularly quickly, whereas repairs of semantic errors were initiated relatively slowly, regardless of their accuracy. We discuss the implications of these findings for theoretical accounts of self-monitoring and the role of speech error repair in learning.

Spatiotemporal dynamics of word retrieval in speech production revealed by cortical high-frequency band activity

Word retrieval is core to language production and relies on complementary processes: the rapid activation of lexical and conceptual representations and word selection, which chooses the correct word among semantically related competitors. Lexical and conceptual activation is measured by semantic priming. In contrast, word selection is indexed by semantic interference and is hampered in semantically homogeneous (HOM) contexts. We examined the spatiotemporal dynamics of these complementary processes in a picture naming task with blocks of semantically heterogeneous (HET) or HOM stimuli. We used electrocorticography data obtained from frontal and temporal cortices, permitting detailed spatiotemporal analysis of word retrieval processes. A semantic interference effect was observed with naming latencies longer in HOM versus HET blocks. Cortical response strength as indexed by high-frequency band (HFB) activity (70-150 Hz) amplitude revealed effects linked to lexical-semantic activation and word selection observed in widespread regions of the cortical mantle. Depending on the subsecond timing and cortical region, HFB indexed semantic interference (i.e., more activity in HOM than HET blocks) or semantic priming effects (i.e., more activity in HET than HOM blocks). These effects overlapped in time and space in the left posterior inferior temporal gyrus and the left prefrontal cortex. The data do not support a modular view of word retrieval in speech production but rather support substantial overlap of lexical-semantic activation and word selection mechanisms in the brain.

Explicit and Implicit Verbal Response Inhibition in Preschool-Age Children Who Stutter

PURPOSE

The purpose of this study was to examine (a) explicit and implicit verbal response inhibition in preschool children who do stutter (CWS) and do not stutter (CWNS) and (b) the relationship between response inhibition and language skills.

METHOD

Participants were 41 CWS and 41 CWNS between the ages of 3;1 and 6;1 (years;months). Explicit verbal response inhibition was measured using a computerized version of the grass-snow task (Carlson & Moses, 2001), and implicit verbal response inhibition was measured using the baa-meow task. Main dependent variables were reaction time and accuracy.

RESULTS

The CWS were significantly less accurate than the CWNS on the implicit task, but not the explicit task. The CWS also exhibited slower reaction times than the CWNS on both tasks. Between-group differences in performance could not be attributed to working memory demands. Overall, children's performance on the inhibition tasks corresponded with parents' perceptions of their children's inhibition skills in daily life.

CONCLUSIONS

CWS are less effective and efficient than CWNS in suppressing a dominant response while executing a conflicting response in the verbal domain.

A common neural hub resolves syntactic and non-syntactic conflict through cooperation with task-specific networks

Regions within the left inferior frontal gyrus (LIFG) have simultaneously been implicated in syntactic processing and cognitive control. Accounts attempting to unify LIFG's function hypothesize that, during comprehension, cognitive control resolves conflict between incompatible representations of sentence meaning. Some studies demonstrate co-localized activity within LIFG for syntactic and non-syntactic conflict resolution, suggesting domain-generality, but others show non-overlapping activity, suggesting domain-specific cognitive control and/or regions that respond uniquely to syntax. We propose however that examining exclusive activation sites for certain contrasts creates a false dichotomy: both domain-general and domain-specific neural machinery must coordinate to facilitate conflict resolution across domains. Here, subjects completed four diverse tasks involving conflict -one syntactic, three non-syntactic- while undergoing fMRI. Though LIFG consistently activated within individuals during conflict processing, functional connectivity analyses revealed task-specific coordination with distinct brain networks. Thus, LIFG may function as a conflict-resolution "hub" that cooperates with specialized neural systems according to information content.

Subjective experience of inner speech in aphasia: Preliminary behavioral relationships and neural correlates

Many individuals with aphasia describe anomia with comments like "I know it but I can't say it." The exact meaning of such phrases is unclear. We hypothesize that at least two discrete experiences exist: the sense of (1) knowing a concept, but failing to find the right word, and (2) saying the correct word internally but not aloud (successful inner speech, sIS). We propose that sIS reflects successful lexical access; subsequent overt anomia indicates post-lexical output deficits. In this pilot study, we probed the subjective experience of anomia in 37 persons with aphasia. Self-reported sIS related to aphasia severity and phonological output deficits. In multivariate lesion-symptom mapping, sIS was associated with dorsal stream lesions, particularly in ventral sensorimotor cortex. These preliminary results suggest that people with aphasia can often provide meaningful insights about their experience of anomia and that reports of sIS relate to specific lesion locations and language deficits.

Grammatical Constraints on Language Switching: Language Control is not Just Executive Control

The current study investigated the roles of grammaticality and executive control on bilingual language selection by examining production speed and failures of language control, or intrusion errors (e.g., saying el instead of the), in young and aging bilinguals. Production of mixed-language connected speech was elicited by asking Spanish-English bilinguals to read aloud paragraphs that had mostly grammatical (conforming to naturally occurring constraints) or mostly ungrammatical (haphazard mixing) language switches, and low or high switching rate. Mixed-language speech was slower and less accurate when switch-rate was high, but especially (for speed) or only (for intrusion errors) if switches were also ungrammatical. Executive function ability (measured with a variety of tasks in young bilinguals in Experiment 1, and aging bilinguals in Experiment 2), slowed production and increased intrusion rate in a generalized fashion, but with little or no interaction with grammaticality. Aging effects appeared to reflect reduced monitoring ability (evidenced by a lower rate of self-corrected intrusions). These results demonstrate robust effects of grammatical encoding on language selection, and imply that executive control influences bilingual language production only after sentence planning and lexical selection.

Executive Function and Ambiguous Sentence Comprehension

PURPOSE

Sentence comprehension is a critical skill in today's literate society. Recent evidence suggests that processing and comprehending language taps cognitive as well as linguistic abilities, a finding that has critical import for clinicians who have clients with language disorders. To promote awareness of the impact of cognition, especially executive function (EF) and working memory (WM), this opinion article presents current views of how sentences are processed and links the various steps of the process to specific EF and WM subcomponents.

METHOD

The article focuses on ambiguous sentences, pointing out the similar types of processing needed when resolving an ambiguity and performing EF tasks.

RESULTS

We discuss the potential overlap between the neurobiology of sentence processing and EF and the evidence supporting a link between EF and sentence processes.

CONCLUSION

Awareness of the potential role of EF and WM in sentence comprehension will help clinicians be more aware of potential cognitive-linguistic deficits in their clients. Future research will help to clarify the link between EF and sentence comprehension.

Cognitive control during selection and repair in word production

Production of an intended word entails selection processes, in which first the lexical item and then its segments are selected among competitors, as well as processes that covertly or overtly repair dispreferred words. In two experiments, we studied the locus of the control processes involved in selection (selection control) and intercepting errors (post-monitoring control). Selection control was studied by manipulating the overlap (contextual similarity) in either semantics or in segments between two objects that participants repeatedly named. Post-monitoring control was examined by asking participants to reverse, within each block, the name of the two objects that were either semantically- or segmentally-related, thus suppressing a potent, but incorrect, response in favor of an alternative (reversal). Results showed robust costs of both contextual similarity (which increased with the degree of similarity between target and context) and reversal, but the two did not interact with one another. Analysis of individual differences revealed no reliable correlation between the cost of contextual similarity when pairs were semantically- or segmentally-related, suggesting stage-specific selection control processes. On the other hand, the cost of reversal was reliably correlated between semantically- and segmentally-related pairs, implying a different control process that is shared by both stages of production. Collectively, these results support a model in which selection control operates separately at lexical and segmental selection stages, but post-monitoring control operates on the segmentally-encoded outcome.

Does naming accuracy improve through self-monitoring of errors?

This study examined spontaneous self-monitoring of picture naming in people with aphasia. Of primary interest was whether spontaneous detection or repair of an error constitutes an error signal or other feedback that tunes the production system to the desired outcome. In other words, do acts of monitoring cause adaptive change in the language system? A second possibility, not incompatible with the first, is that monitoring is indicative of an item's representational strength, and strength is a causal factor in language change. Twelve PWA performed a 615-item naming test twice, in separate sessions, without extrinsic feedback. At each timepoint, we scored the first complete response for accuracy and error type and the remainder of the trial for verbalizations consistent with detection (e.g., "no, not that") and successful repair (i.e., correction). Data analysis centered on: (a) how often an item that was misnamed at one timepoint changed to correct at the other timepoint, as a function of monitoring; and (b) how monitoring impacted change scores in the Forward (Time 1 to Time 2) compared to Backward (Time 2 to Time 1) direction. The Strength hypothesis predicts significant effects of monitoring in both directions. The Learning hypothesis predicts greater effects in the Forward direction. These predictions were evaluated for three types of errors--Semantic errors, Phonological errors, and Fragments--using mixed-effects regression modeling with crossed random effects. Support for the Strength hypothesis was found for all three error types. Support for the Learning hypothesis was found for Semantic errors. All effects were due to error repair, not error detection. We discuss the theoretical and clinical implications of these novel findings.

Conflict monitoring in speech processing: An fMRI study of error detection in speech production and perception

To minimize the number of errors in speech, and thereby facilitate communication, speech is monitored before articulation. It is, however, unclear at which level during speech production monitoring takes place, and what mechanisms are used to detect and correct errors. The present study investigated whether internal verbal monitoring takes place through the speech perception system, as proposed by perception-based theories of speech monitoring, or whether mechanisms independent of perception are applied, as proposed by production-based theories of speech monitoring. With the use of fMRI during a tongue twister task we observed that error detection in internal speech during noise-masked overt speech production and error detection in speech perception both recruit the same neural network, which includes pre-supplementary motor area (pre-SMA), dorsal anterior cingulate cortex (dACC), anterior insula (AI), and inferior frontal gyrus (IFG). Although production and perception recruit similar areas, as proposed by perception-based accounts, we did not find activation in superior temporal areas (which are typically associated with speech perception) during internal speech monitoring in speech production as hypothesized by these accounts. On the contrary, results are highly compatible with a domain general approach to speech monitoring, by which internal speech monitoring takes place through detection of conflict between response options, which is subsequently resolved by a domain general executive center (e.g., the ACC).

Did I say dog or cat? A study of semantic error detection and correction in children

Although naturalistic studies of spontaneous speech suggest that young children can monitor their speech, the mechanisms for detection and correction of speech errors in children are not well understood. In particular, there is little research on monitoring semantic errors in this population. This study provides a systematic investigation of detection and correction of semantic errors in children between the ages of 5 and 8years as they produced sentences to describe simple visual events involving nine highly familiar animals (the moving animals task). Results showed that older children made fewer errors and corrected a larger proportion of the errors that they made than younger children. We then tested the prediction of a production-based account of error monitoring that the strength of the language production system, and specifically its semantic-lexical component, should be correlated with the ability to detect and repair semantic errors. Strength of semantic-lexical mapping, as well as lexical-phonological mapping, was estimated individually for children by fitting their error patterns, obtained from an independent picture-naming task, to a computational model of language production. Children's picture-naming performance was predictive of their ability to monitor their semantic errors above and beyond age. This relationship was specific to the strength of the semantic-lexical part of the system, as predicted by the production-based monitor.

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.

Anticipation in stuttering: A theoretical model of the nature of stutter prediction

The fact that some people who stutter have the ability to anticipate a stuttering moment is essential for several theories of stuttering and important for maximum effectiveness of many currently used treatment techniques. The "anticipation effect," however, is poorly understood despite much investigation into this phenomenon. In the present paper, we combine (1) behavioral evidence from the stuttering-anticipation literature, (2) speech production models, and (3) models of error detection to propose a theoretical model of anticipation. Integrating evidence from theories such as Damasio's Somatic Marker Hypothesis, Levelt's Perceptual Monitoring Theory, Guenther's The Directions Into Velocities of Articulators (DIVA) model, Postma's Covert Repair Hypothesis, among others, our central thesis is that the anticipation of a stuttering moment occurs as an outcome of the interactions between previous learning experiences (i.e., learnt associations between stuttered utterances and any self-experienced or environmental consequence) and error monitoring. Possible neurological mechanisms involved in generating conscious anticipation are also discussed, along with directions for future research.

EDUCATIONAL OBJECTIVES

The reader will be able to: (a) describe historical theories that explain how PWS may learn to anticipate stuttering; (b) state some traditional sources of evidence of anticipation in stuttering; (c) describe how PWS may be sensitive to the detection of a stuttering; (d) state some of the neural correlates that may underlie anticipation in stuttering; and (e) describe some of the possible utilities of incorporating anticipation into stuttering interventions.

Prolegomena to a neurocomputational architecture for human grammatical encoding and decoding

This study develops a neurocomputational architecture for grammatical processing in language production and language comprehension (grammatical encoding and decoding, respectively). It seeks to answer two questions. First, how is online syntactic structure formation of the complexity required by natural-language grammars possible in a fixed, preexisting neural network without the need for online creation of new connections or associations? Second, is it realistic to assume that the seemingly disparate instantiations of syntactic structure formation in grammatical encoding and grammatical decoding can run on the same neural infrastructure? This issue is prompted by accumulating experimental evidence for the hypothesis that the mechanisms for grammatical decoding overlap with those for grammatical encoding to a considerable extent, thus inviting the hypothesis of a single "grammatical coder." The paper answers both questions by providing the blueprint for a syntactic structure formation mechanism that is entirely based on prewired circuitry (except for referential processing, which relies on the rapid learning capacity of the hippocampal complex), and can subserve decoding as well as encoding tasks. The model builds on the "Unification Space" model of syntactic parsing developed by Vosse and Kempen (Cognition 75:105-143, 2000; Cognitive Neurodynamics 3:331-346, 2009a). The design includes a neurocomputational mechanism for the treatment of an important class of grammatical movement phenomena.

Cascading activation from lexical processing to letter-level processing in written word production

Descriptions of language production have identified processes involved in producing language and the presence and type of interaction among those processes. In the case of spoken language production, consensus has emerged that there is interaction among lexical selection processes and phoneme-level processing. This issue has received less attention in written language production. In this paper, we present a novel analysis of the writing-to-dictation performance of an individual with acquired dysgraphia revealing cascading activation from lexical processing to letter-level processing. The individual produced frequent lexical-semantic errors (e.g., chipmunk → SQUIRREL) as well as letter errors (e.g., inhibit → INBHITI) and had a profile consistent with impairment affecting both lexical processing and letter-level processing. The presence of cascading activation is suggested by lower letter accuracy on words that are more weakly activated during lexical selection than on those that are more strongly activated. We operationalize weakly activated lexemes as those lexemes that are produced as lexical-semantic errors (e.g., lethal in deadly → LETAHL) compared to strongly activated lexemes where the intended target word (e.g., lethal) is the lexeme selected for production.

The effects of anodal stimulation of the left prefrontal cortex on sentence production

BACKGROUND

Most studies in which Anodal Transcranial Direct Current Stimulation (A-tDCS) has been used to improve language production have focused on single words. Yet sentence production requires more than lexical retrieval. For example, successful suppression of the past and careful planning of the future are two critical requirements for producing a correct sentence. Can A-tDCS improves those, and by extension, production at the sentence level?

OBJECTIVE/HYPOTHESIS

Given that many aspects of sentence production beyond word retrieval require frontally-mediated operations, we hypothesized that A-tDCS to the left prefrontal cortex should benefit various operation involved in producing sentences, two of which, suppression of the past and planning of the future, were targeted in this study.

METHODS

We used a paradigm that elicited construction of sentences through event description, but was structured enough to allow for between-subject comparison, clear error identification, and implementation of experimental manipulations to probe certain aspects of production.

RESULTS

We showed that A-tDCS to the left PFC reliably decreased the number of incomplete and errorful sentences. When the origin of this improvement was probed, we found that A-tDCS significantly decreased errors due to premature commitment to the future word (insufficient internal monitoring), and had a marginal effect on errors of perseverations (insufficient suppression of the past).

CONCLUSION

We conclude that A-tDCS is a promising tool for improving production at the sentence level, and that improvement can be expected when internal monitoring and control over verbal responses is impaired, or for certain cases of perseveratory errors.

Speakers’ Acceptance of Real-Time Speech Exchange Indicates That We Use Auditory Feedback to Specify the Meaning of What We Say

Speech is usually assumed to start with a clearly defined preverbal message, which provides a benchmark for self-monitoring and a robust sense of agency for one’s utterances. However, an alternative hypothesis states that speakers often have no detailed preview of what they are about to say, and that they instead use auditory feedback to infer the meaning of their words. In the experiment reported here, participants performed a Stroop color-naming task while we covertly manipulated their auditory feedback in real time so that they said one thing but heard themselves saying something else. Under ideal timing conditions, two thirds of these semantic exchanges went undetected by the participants, and in 85% of all nondetected exchanges, the inserted words were experienced as self-produced. These findings indicate that the sense of agency for speech has a strong inferential component, and that auditory feedback of one’s own voice acts as a pathway for semantic monitoring, potentially overriding other feedback loops.