The State of Cognitive Control in Language Processing.

Understanding language requires readers and listeners to cull meaning from fast-unfolding messages that often contain conflicting cues pointing to incompatible ways of interpreting the input (e.g., "The cat was chased by the mouse"). This article reviews mounting evidence from multiple methods demonstrating that cognitive control plays an essential role in resolving conflict during language comprehension. How does cognitive control accomplish this task? Psycholinguistic proposals have conspicuously failed to address this question. We introduce an account in which cognitive control aids language processing when cues conflict by sending top-down biasing signals that strengthen the interpretation supported by the most reliable evidence available. We also provide a computationally plausible model that solves the critical problem of how cognitive control "knows" which way to direct its biasing signal by allowing linguistic knowledge itself to issue crucial guidance. Such a mental architecture can explain a range of experimental findings, including how moment-to-moment shifts in cognitive-control state-its level of activity within a person-directly impact how quickly and successfully language comprehension is achieved.

Moving From Bilingual Traits to States: Understanding Cognition and Language Processing Through Moment-to-Moment Variation.

The study of how bilingualism is linked to cognitive processing, including executive functioning, has historically focused on comparing bilinguals to monolinguals across a range of tasks. These group comparisons presume to capture relatively stable cognitive traits and have revealed important insights about the architecture of the language processing system that could not have been gleaned from studying monolinguals alone. However, there are drawbacks to using a group-comparison, or Traits, approach. In this theoretical review, we outline some limitations of treating executive functions as stable traits and of treating bilinguals as a uniform group when compared to monolinguals. To build on what we have learned from group comparisons, we advocate for an emerging complementary approach to the question of cognition and bilingualism. Using an approach that compares bilinguals to themselves under different linguistic or cognitive contexts allows researchers to ask questions about how language and cognitive processes interact based on dynamically fluctuating cognitive and neural states. A States approach, which has already been used by bilingualism researchers, allows for cause-and-effect hypotheses and shifts our focus from questions of group differences to questions of how varied linguistic environments influence cognitive operations in the moment and how fluctuations in cognitive engagement impact language processing.

Does integrating a code-switch during comprehension engage cognitive control?

We investigated whether bilinguals' integration of a code-switch during real-time comprehension, which involves resolving among conflicting linguistic representations, modulates the deployment of cognitive-control mechanisms. In the current experiment, Spanish-English bilinguals (N = 48) completed a cross-task conflict-adaptation paradigm that tested whether reading code-switched sentences triggers cognitive-control engagement that immediately influences performance on an ensuing Flanker trial. We observed that, while incrementally processing sentences, detecting a code-switch (as opposed to reading sentences that did not contain a code-switch) assisted subsequent conflict resolution. Such temporal interdependence between confronting cross-linguistic conflict and ensuing adjustments in behavior indicates that integrating a code-switch during online comprehension may recruit domain-general cognitive-control procedures. We propose that such control mechanisms mobilize to resolve among competing representations that arise across languages during real-time parsing of code-switched input. Overall, the findings provide novel insight into what language-processing demands of bilingualism regulate cognitive-control performance moment by moment. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Who did what? A causal role for cognitive control in thematic role assignment during sentence comprehension.

Thematic role assignment - generally, figuring out who did what to whom - is a critical component of sentence comprehension, which is influenced by both syntactic and semantic cues. Conflict between these cues can result in temporary consideration of multiple incompatible interpretations during real-time sentence processing. We tested whether the resolution of syntax-semantics conflict can be expedited by the online engagement of cognitive control processes that are routinely used to regulate behavior across domains. In this study, cognitive control deployment from a previous Stroop trial influenced eye movements during subsequent sentence comprehension. Specifically, when syntactic and semantic cues competed for influence on interpretation, dynamic cognitive control engagement led to (a) fewer overall looks to a picture illustrating the competing but incorrect interpretation (Experiment 1), or (b) steeper growth in looks to a picture illustrating the correct interpretation (Experiment 2). Thus, prior cognitive control engagement facilitated the resolution of syntax-semantics conflict by biasing processing towards the intended analysis. This conflict adaptation effect demonstrates a causal connection between cognitive control and real-time thematic role assignment. Broader patterns demonstrated that prior cognitive control engagement also modulated sentence processing irrespective of the presence of conflict, reflecting increased integration of newly arriving cues with prior sentential content. Together, the results suggest that cognitive control helps listeners determine correct event roles during real-time comprehension.

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.

Memory and language improvements following cognitive control training.

Cognitive control refers to adjusting thoughts and actions when confronted with conflict during information processing. We tested whether this ability is causally linked to performance on certain language and memory tasks by using cognitive control training to systematically modulate people's ability to resolve information-conflict across domains. Different groups of subjects trained on 1 of 3 minimally different versions of an n-back task: n-back-with-lures (High-Conflict), n-back-without-lures (Low-Conflict), or 3-back-without-lures (3-Back). Subjects completed a battery of recognition memory and language processing tasks that comprised both high- and low-conflict conditions before and after training. We compared the transfer profiles of (a) the High- versus Low-Conflict groups to test how conflict resolution training contributes to transfer effects, and (b) the 3-Back versus Low-Conflict groups to test for differences not involving cognitive control. High-Conflict training-but not Low-Conflict training-produced discernable benefits on several untrained transfer tasks, but only under selective conditions requiring cognitive control. This suggests that the conflict-focused intervention influenced functioning on ostensibly different outcome measures across memory and language domains. 3-Back training resulted in occasional improvements on the outcome measures, but these were not selective for conditions involving conflict resolution. We conclude that domain-general cognitive control mechanisms are plastic, at least temporarily, and may play a causal role in linguistic and nonlinguistic performance. (PsycINFO Database Record

Dynamic Engagement of Cognitive Control Modulates Recovery From Misinterpretation During Real-Time Language Processing.

Speech unfolds swiftly, yet listeners keep pace by rapidly assigning meaning to what they hear. Sometimes, though, initial interpretations turn out to be wrong. How do listeners revise misinterpretations of language input moment by moment to avoid comprehension errors? Cognitive control may play a role by detecting when processing has gone awry and then initiating behavioral adjustments accordingly. However, no research to date has investigated a cause-and-effect interplay between cognitive-control engagement and the overriding of erroneous interpretations in real time. Using a novel cross-task paradigm, we showed that Stroop-conflict detection, which mobilizes cognitive-control procedures, subsequently facilitates listeners' incremental processing of temporarily ambiguous spoken instructions that induce brief misinterpretation. When instructions followed incongruent Stroop items, compared with congruent Stroop items, listeners' eye movements to objects in a scene reflected more transient consideration of the false interpretation and earlier recovery of the correct one. Comprehension errors also decreased. Cognitive-control engagement therefore accelerates sentence-reinterpretation processes, even as linguistic input is still unfolding.

The effects of bilingualism on conflict monitoring, cognitive control, and garden-path recovery.

Bilinguals demonstrate benefits on non-linguistic tasks requiring cognitive control-the regulation of mental activity to resolve information-conflict during processing. This "bilingual advantage" has been attributed to the consistent management of two languages, yet it remains unknown if these benefits extend to sentence processing. In monolinguals, cognitive control helps detect and revise misinterpretations of sentence meaning. Here, we test if the bilingual advantage extends to parsing and interpretation by comparing bilinguals' and monolinguals' syntactic ambiguity resolution before and after practicing N-back, a non-syntactic cognitive-control task. Bilinguals outperformed monolinguals on a high-conflict but not a no-conflict version of N-back and on sentence comprehension, indicating that the advantage extends to language interpretation. Gains on N-back conflict trials also predicted comprehension improvements for ambiguous sentences, suggesting that the bilingual advantage emerges across tasks tapping shared cognitive-control procedures. Because the overall task benefits were observed for conflict and non-conflict trials, bilinguals' advantage may reflect increased cognitive flexibility.

The development and malleability of executive control abilities.

Executive control (EC) generally refers to the regulation of mental activity. It plays a crucial role in complex cognition, and EC skills predict high-level abilities including language processing, memory, and problem solving, as well as practically relevant outcomes such as scholastic achievement. EC develops relatively late in ontogeny, and many sub-groups of developmental populations demonstrate an exaggeratedly poor ability to control cognition even alongside the normal protracted growth of EC skills. Given the value of EC to human performance, researchers have sought means to improve it through targeted training; indeed, accumulating evidence suggests that regulatory processes are malleable through experience and practice. Nonetheless, there is a need to understand both whether specific populations might particularly benefit from training, and what cortical mechanisms engage during performance of the tasks used in the training protocols. This contribution has two parts: in Part I, we review EC development and intervention work in select populations. Although promising, the mixed results in this early field make it difficult to draw strong conclusions. To guide future studies, in Part II, we discuss training studies that have included a neuroimaging component - a relatively new enterprise that also has not yet yielded a consistent pattern of results post-training, preventing broad conclusions. We therefore suggest that recent developments in neuroimaging (e.g., multivariate and connectivity approaches) may be useful to advance our understanding of the neural mechanisms underlying the malleability of EC and brain plasticity. In conjunction with behavioral data, these methods may further inform our understanding of the brain-behavior relationship and the extent to which EC is dynamic and malleable, guiding the development of future, targeted interventions to promote executive functioning in both healthy and atypical populations.

To adapt or not to adapt: the question of domain-general cognitive control.

What do perceptually bistable figures, sentences vulnerable to misinterpretation and the Stroop task have in common? Although seemingly disparate, they all contain elements of conflict or ambiguity. Consequently, in order to monitor a fluctuating percept, reinterpret sentence meaning, or say "blue" when the word RED is printed in blue ink, individuals must regulate attention and engage cognitive control. According to the Conflict Monitoring Theory (Botvinick, Braver, Barch, Carter, & Cohen, 2001), the detection of conflict automatically triggers cognitive control mechanisms, which can enhance resolution of subsequent conflict, namely, "conflict adaptation." If adaptation reflects the recruitment of domain-general processes, then conflict detection in one domain should facilitate conflict resolution in an entirely different domain. We report two novel findings: (i) significant conflict adaptation from a syntactic to a non-syntactic domain and (ii) from a perceptual to a verbal domain, providing strong evidence that adaptation is mediated by domain-general cognitive control.

Memory and cognitive control in an integrated theory of language processing.

Pickering & Garrod's (P&G's) integrated model of production and comprehension includes no explicit role for nonlinguistic cognitive processes. Yet, how domain-general cognitive functions contribute to language processing has become clearer with well-specified theories and supporting data. We therefore believe that their account can benefit by incorporating functions like working memory and cognitive control into a unified model of language processing.

The benefits of executive control training and the implications for language processing.

Recent psycholinguistics research suggests that the executive function (EF) skill known as conflict resolution - the ability to adjust behavior in the service of resolving among incompatible representations - is important for several language processing tasks such as lexical and syntactic ambiguity resolution, verbal fluency, and common-ground assessment. Here, we discuss work showing that various EF skills can be enhanced through consistent practice with working-memory tasks that tap these EFs, and, moreover, that improvements on the training tasks transfer across domains to novel tasks that may rely on shared underlying EFs. These findings have implications for language processing and could launch new research exploring if EF training, within a "process-specific" framework, could be used as a remediation tool for improving general language use. Indeed, work in our lab demonstrates that EF training that increases conflict-resolution processes has selective benefits on an untrained sentence-processing task requiring syntactic ambiguity resolution, which relies on shared conflict-resolution functions. Given claims that conflict-resolution abilities contribute to a range of linguistic skills, EF training targeting this process could theoretically yield wider performance gains beyond garden-path recovery. We offer some hypotheses on the potential benefits of EF training as a component of interventions to mitigate general difficulties in language processing. However, there are caveats to consider as well, which we also address.

The other side of cognitive control: can a lack of cognitive control benefit language and cognition?

Cognitive control refers to the regulation of mental activity to support flexible cognition across different domains. Cragg and Nation (2010) propose that the development of cognitive control in children parallels the development of language abilities, particularly inner speech. We suggest that children's late development of cognitive control also mirrors their limited ability to revise misinterpretations of sentence meaning. Moreover, we argue that for certain tasks, a tradeoff between bottom-up (data-driven) and top-down (rule-based) thinking may actually benefit performance in both children and adults. Specifically, we propose that a lack of cognitive control may promote important aspects of cognitive development, like language acquisition and creativity.

A case for conflict across multiple domains: memory and language impairments following damage to ventrolateral prefrontal cortex.

Patients with focal lesions to the left inferior frontal gyrus (LIFG; BA 44/45) exhibit difficulty with language production and comprehension tasks, although the nature of their impairments has been somewhat difficult to characterize. No reported cases suggest that these patients are Broca's aphasics in the classic agrammatic sense. Recent case studies, however, do reveal a consistent pattern of deficit regarding their general cognitive processes: they are reliably impaired on tasks in which conflicting representations must be resolved by implementing top-down cognitive control (e.g., Stroop; memory tasks involving proactive interference). In the present study, we ask whether the language production and comprehension impairments displayed by a patient with circumscribed LIFG damage can best be understood within a general conflict resolution deficit account. We focus on one patient in particular--patient I.G.--and discuss the implications for language processing abilities as a consequence of a general cognitive control disorder. We compared I.G. and other frontal patients to age-matched control participants across four experiments. Experiment 1 tested participants' general conflict resolution abilities within a modified working memory paradigm in an attempt to replicate prior case study findings. We then tested language production abilities on tasks of picture naming (Experiment 2) and verbal fluency (Experiment 3), tasks that generated conflict at the semantic and/or conceptual levels. Experiment 4 tested participants' sentence processing and comprehension abilities using both online (eye movement) and offline measures. In this task, participants carried out spoken instructions containing a syntactic ambiguity, in which early interpretation commitments had to be overridden in order to recover an alternative, intended analysis of sentence meaning. Comparisons of I.G.'s performance with frontal and healthy control participants supported the following claim: I.G. suffers from a general conflict resolution impairment, which affects his ability to produce and comprehend language under specific conditions--namely, when semantic, conceptual, and/or syntactic representations compete and must be resolved.

Putting lexical constraints in context into the visual-world paradigm.

Prior eye-tracking studies of spoken sentence comprehension have found that the presence of two potential referents, e.g., two frogs, can guide listeners toward a Modifier interpretation of Put the frog on the napkin... despite strong lexical biases associated with Put that support a Goal interpretation of the temporary ambiguity (Tanenhaus, M. K., Spivey-Knowlton, M. J., Eberhard, K. M. & Sedivy, J. C. (1995). Integration of visual and linguistic information in spoken language comprehension. Science, 268, 1632-1634; Trueswell, J. C., Sekerina, I., Hill, N. M. & Logrip, M. L. (1999). The kindergarten-path effect: Studying on-line sentence processing in young children. Cognition, 73, 89-134). This pattern is not expected under constraint-based parsing theories: cue conflict between the lexical evidence (which supports the Goal analysis) and the visuo-contextual evidence (which supports the Modifier analysis) should result in uncertainty about the intended analysis and partial consideration of the Goal analysis. We reexamined these put studies (Experiment 1) by introducing a response time-constraint and a spatial contrast between competing referents (a frog on a napkin vs. a frog in a bowl). If listeners immediately interpret on the... as the start of a restrictive modifier, then their eye movements should rapidly converge on the intended referent (the frog on something). However, listeners showed this pattern only when the phrase was unambiguously a Modifier (Put the frog that's on the...). Syntactically ambiguous trials resulted in transient consideration of the Competitor animal (the frog in something). A reading study was also run on the same individuals (Experiment 2) and performance was compared between the two experiments. Those individuals who relied heavily on lexical biases to resolve a complement ambiguity in reading (The man heard/realized the story had been...) showed increased sensitivity to both lexical and contextual constraints in the put-task; i.e., increased consideration of the Goal analysis in 1-Referent Scenes, but also adeptness at using spatial constraints of prepositions (in vs. on) to restrict referential alternatives in 2-Referent Scenes. These findings cross-validate visual world and reading methods and support multiple-constraint theories of sentence processing in which individuals differ in their sensitivity to lexical contingencies.

Cognitive control and parsing: reexamining the role of Broca's area in sentence comprehension.

A century of investigation into the role of the human frontal lobes in complex cognition, including language processing, has revealed several interesting but apparently contradictory findings. In particular, the results of numerous studies suggest that left inferior frontal gyrus (LIFG), which includes Broca's area, plays a direct role in sentence-level syntactic processing. In contrast, other brain-imaging and neuropsychological data indicate that LIFG is crucial for cognitive control--specifically, for overriding highly regularized, automatic processes, even when a task involves syntactically undemanding material (e.g., single words, a list of letters). We provide a unifying account of these findings, which emphasizes the importance of general cognitive control mechanisms for the syntactic processing of sentences. On the basis of a review of the neurocognitive and sentence-processing literatures, we defend the following three hypotheses: (1) LIFG is part of a network of frontal lobe subsystems that are generally responsible for the detection and resolution of incompatible stimulus representations; (2) the role of LIFG in sentence comprehension is to implement reanalysis in the face of misinterpretation; and (3) individual differences in cognitive control abilities in nonsyntactic tasks predict correlated variation in sentence-processing abilities pertaining to the recovery from misinterpretation.

Studying the grammatical aspects of word recognition: lexical priming, parsing, and syntactic ambiguity resolution.

Two experiments are reported examining the relationship between lexical and syntactic processing during language comprehension, combining techniques common to the on-line study of syntactic ambiguity resolution with priming techniques common to the study of lexical processing. By manipulating grammatical properties of lexical primes, we explore how lexically based knowledge is activated and guides combinatory sentence processing. Particularly, we find that nouns (like verbs, see Trueswell & Kim, 1998) can activate detailed lexically specific syntactic information and that these representations guide the resolution of relevant syntactic ambiguities pertaining to verb argument structure. These findings suggest that certain principles of knowledge representation common to theories of lexical knowledge--such as overlapping and distributed representations--also characterize grammatical knowledge. Additionally, observations from an auditory comprehension study suggest similar conclusions about the lexical nature of parsing in spoken language comprehension. They also suggest that thematic role and syntactic preferences are activated during word recognition and that both influence combinatory processing.