Aspects Of Cognitive Control Research Articles

Let your fingers do the walking: Finger force distinguishes competing accounts of the congruency sequence effect.

The ability to remain flexible while engaging in goal-directed behavior is a critical aspect of cognitive control. A classic example of such flexibility is the congruency sequence effect (CSE) in distractor-interference tasks. In such tasks, participants respond more slowly when a distractor cues a different response than a target (incongruent trials) than when it cues the same response (congruent trials). However, this congruency effect is smaller after incongruent trials than after congruent trials. Interestingly, recent data from the prime-probe task indicate that this CSE is largest when participants treat the distractor, or prime, as the first of two temporally separated targets. It remains unclear, however, whether the CSE in this task indexes (1) control processes that modulate response activation before the second target (i.e., probe) appears or (2) congruency switch costs that delay responses after the probe appears. To distinguish between these accounts, participants' responses were recorded with force-sensitive keys. After responding to the prime, but before the probe appeared, participants exerted greater force on (1) the key cued by the prime after congruent trials, but on (2) the opposite key after incongruent trials. These findings indicate that the ability to remain flexible while engaging in goal-directed behavior relies on control processes that modulate response activation prior to the appearance of a goal-relevant stimulus.

Attentional Fluctuations, Cognitive Flexibility, and Bilingualism in Kindergarteners.

The idea of a bilingual advantage in aspects of cognitive control—including cognitive flexibility, inhibition, working memory, and attention—is disputed. Using a sample of kindergarten children, the present study investigated associations between bilingualism and cognitive flexibility—a relationship that has shown mixed findings in prior literature. We also extend prior work by exploring relationships between bilingualism and attentional fluctuations, which represent consistency in attentional control and contribute to cognitive performance. To our knowledge, no previous study has explored this association. Theoretically, attentional fluctuations might mediate or moderate the relationship between bilingualism and cognitive flexibility. However, given evidence of null findings from extant literature when confounding variables are adequately controlled and tasks are standardized, we did not expect to find a bilingual advantage in either cognitive flexibility or attentional fluctuations. Our results supported this hypothesis when considering bilingualism both continuously and categorically. The importance of expanding upon mechanistic accounts connecting bilingualism to cognitive improvements is discussed.

The impact of stimulus modality on the processing of conflicting sensory information during response inhibition

Response inhibition is a central aspect of cognitive control. Usually, response inhibition is examined using information from a single sensory modality. Yet, evidence suggests that conflicts between information from different modalities affect response inhibition. It is, however, crucial to consider that there are modality differences in the efficiency to trigger response inhibition that may also modulate the impact of conflicts between different sensory modalities. In the current study, we compared an auditory–tactile to an auditory–visual Go/NO-GO task. We recorded EEG data and performed signal decomposition and source localization. On the behavioral level, we show stronger interference effects in the visual than the tactile modality. Despite sensory processes were experimentally varied, temporally decomposed EEG data show that response selection mechanisms are associated with these effects and not the sensory processing stage. These modulations of response selection processes occur in the temporo-parietal junction (TPJ, BA40) and inferior frontal structures (IFG, BA47). The smaller activity in the TPJ during auditory–tactile, compared to auditory–visual conflicts suggests that task representations are less affected by interfering auditory information when the tactile modality informs response inhibition processes. This also explains why less intense braking processes (reflected by IFG activity) are still able to maintain a reasonable response inhibition performance level. It can be concluded that the tactile and visual domains do not only differ in regard to their efficiency to trigger response inhibition processes but also in their susceptibility to interference while informing inhibitory control. Clinical implications are discussed.

The orexin-1 receptor antagonist SB-334867 reduces motivation, but not inhibitory control, in a rat stop signal task

There is considerable clinical interest in the neuropeptide orexin/hypocretin for its ability to regulate motivation and reward as well as arousal and wakefulness. For instance, antagonists for the orexin-1 receptor (OxR1) are thought to hold great promise for treating drug addiction and disorders associated with overeating, as these compounds repeatedly have been found to suppress seeking of various drugs of abuse as well as highly palatable foods in preclinical models. Given the hypothesized role of OxR1 signaling in cue-driven motivation, an outstanding question is whether pharmacologically blocking this receptor affects cognitive functioning. Response inhibition – the ability to cancel ongoing behavior – is one aspect of cognitive control that may be particularly relevant. Response inhibition deficits are commonly associated with a range of psychiatric disorders and neurological diseases, including substance use disorders and obesity. Moreover, OxR1 signaling recently has been implicated in waiting impulsivity, another aspect of inhibitory control. Here, we investigated the effects of the OxR1 antagonist SB-334867 on response inhibition in a rat version of the stop-signal reaction time task. Results show that acutely blocking OxR1 had minimal effects on response inhibition or attentional functioning. In contrast, this manipulation reduced motivation to perform the task and earn food rewards, consistent with other recent findings. These results add to the growing body of literature implicating OxR1 in the regulation of motivation and suggest that effects of pharmacological compounds such as SB-334867 on drug-seeking behavior are not related to effects on response inhibition.

Cognitive Resources Moderate the Relationship Between Pro-Environmental Attitudes and Green Behavior

Given the urgency of climate change mitigation, motivating individuals to behave in sustainable ways constitutes a key challenge for environmental science. Although many studies evidence people’s long-lasting pro-environmental attitudes, such attitudes often do not translate into behavior. The present research hypothesizes that cognitive resources are a crucial moderator, explaining when pro-environmental attitudes turn into behavior. Specifically, we investigate the attitude–behavior gap while taking a “cognition perspective” on environmental behavior. Using experience sampling, the present research demonstrates that individual differences in central aspects of cognitive control (assessed by working memory capacity) moderate the relationship between environmental attitudes and behavior. Our correlational findings suggest that people with positive environmental attitudes also require high working memory capacity to behave in line with their ideals. Our results do not only provide empirical support for recent theorizing in environmental research, but, perhaps more importantly, might offer a central lever for behavioral change initiatives (e.g., “nudging”).

Pupillometric indices of locus-coeruleus activation are not modulated following single bouts of exercise

Single bouts of exercise have been observed to enhance numerous domains of cognition including inhibitory aspects of cognitive control and neuroelectric indices of attention. Given that the locus-coeruleus norepinephrine system regulates alertness and attention, this system may underlie these exercise-induced enhancements. The present study used pupillometry to examine the extent to which a single bout of exercise induces changes in aspects of locus-coeruleus activation, as well as the extent to which changes in locus-coeruleus activation were associated with changes in inhibition and neuroelectric indices of attention. Using a within-participants crossover design, behavioral, neuroelectric, and pupillometric measures were assessed in response to an inhibitory control task before and after 20-min of either aerobic exercise or an active-control condition during two separate, counterbalanced sessions. The aerobic exercise condition consisted of walking/jogging on a motor driven treadmill at an intensity of approximately 70% of age-predicted maximum heart rate. The active control condition consisted of walking on the treadmill at 0.5 mph and 0% grade. Replicating prior findings, enhancements in both reaction time and neuroelectric indices of attention were observed in response to the exercise condition. However, neither the exercise nor the active control conditions were observed to induce changes in activation of the locus-coeruleus as indexed by pupil size, and changes in activation of the locus-coeruleus were not associated with exercise-induced changes in inhibition and neuroelectric indices of attention. Accordingly, these findings provide evidence to suggest that activation of the locus-coeruleus is not a mechanism underlying exercise-induced enhancements in cognition.

Frontal pathways in cognitive control: direct evidence from intraoperative stimulation and diffusion tractography.

A key aspect of cognitive control is the management of conflicting incoming information to achieve a goal, termed 'interference control'. Although the role of the right frontal lobe in interference control is evident, the white matter tracts subserving this cognitive process remain unclear. To investigate this, we studied the effect of transient network disruption (by means of direct electrical stimulation) and permanent disconnection (resulting from neurosurgical resection) on interference control processes, using the Stroop test in the intraoperative and extraoperative neurosurgical setting. We evaluated the sites at which errors could be produced by direct electrical stimulation during an intraoperative Stroop test in 34 patients with frontal right hemisphere glioma. Lesion-symptom mapping was used to evaluate the relationship between the resection cavities and postoperative performance on the Stroop test of this group compared with an additional 29 control patients who did not perform the intraoperative test (63 patients in total aged 17-77 years; 28 female). We then examined tract disruption and disconnection in a subset of eight patients who underwent both the intraoperative Stroop test and high angular resolution diffusion imaging (HARDI) tractography. The results showed that, intraoperatively, the majority of sites associated with errors during Stroop test performance and concurrent subcortical stimulation clustered in a region of white matter medial to the right inferior frontal gyrus, lateral and superior to the striatum. Patients who underwent the intraoperative test maintained cognitive control ability at the 1-month follow-up (P = 0.003). Lesion-symptom analysis showed resection of the right inferior frontal gyrus was associated with slower postoperative Stroop test ability (corrected for multiple comparisons, 5000 permutations). The stimulation sites associated with intraoperative errors most commonly corresponded with the inferior fronto-striatal tracts and anterior thalamic radiation (over 75% of patients), although the latter was commonly resected without postoperative deficits on the Stroop test (in 60% of patients). Our results show converging evidence to support a critical role for the inferior frontal gyrus in interference control processes. The intraoperative data combined with tractography suggests that cortico-subcortical tracts, over cortico-cortical connections, may be vital in maintaining efficiency of cognitive control processes. This suggests the importance of their preservation during resection of right frontal tumours.

Chapter 20 - Aging of the frontal lobe

Healthy aging is associated with numerous deficits in cognitive function, which have been attributed to changes within the prefrontal cortex (PFC). This chapter summarizes some of the most prominent cognitive changes associated with age-related alterations in the anatomy and physiology of the PFC. Specifically, aging of the PFC results in deficient aspects of cognitive control, including sustained attention, selective attention, inhibitory control, working memory, and multitasking abilities. Yet, not all cognitive functions associated with the PFC exhibit age-related declines, such as arithmetic, comprehension, emotion perception, and emotional control. Moreover, not all older adults exhibit declines in cognition. Multiple life-course and lifestyle factors, as well as genetics, play a role in the trajectory of cognitive performance across the life span. Thus many adults retain cognitive function well into advanced age. Moreover, the brain remains plastic throughout life and there is increasing evidence that most age-related declines in cognition can be remediated by various methods such as physical exercise, cognitive training, or noninvasive brain stimulation. Overall, because cognitive aging is associated with numerous life-course and lifestyle factors, successful aging likely begins in early life, while maintaining cognition or remediating declines is a life-long process.

Longitudinal associations between conflict monitoring and emergent academic skills: An event-related potentials study.

Identifying the links between specific cognitive functions and emergent academic skills can help determine pathways to support both early academic performance and later academic achievement. Here, we investigated the longitudinal associations between a key aspect of cognitive control, conflict monitoring, and emergent academic skills from preschool through first grade, in a large sample of socioeconomically diverse children (N=261). We recorded event-related potentials (ERPs) during a Go/No-Go task. The neural index of conflict monitoring, ΔN2, was defined as larger N2 mean amplitudes for No-Go versus Go trials. ΔN2 was observed over the right hemisphere across time points and showed developmental stability. Cross-lagged panel models revealed prospective links from ΔN2 to later math performance, but not reading performance. Specifically, larger ΔN2 at preschool predicted higher kindergarten math performance, and larger ΔN2 at kindergarten predicted higher first-grade math performance, above and beyond the behavioral performance in the Go/No-Go task. Early academic skills did not predict later ΔN2. These findings provided electrophysiological evidence for the contribution of conflict monitoring abilities to emergent math skills. In addition, our findings suggested that neural indices of cognitive control can provide additional information in predicting emergent math skills, above and beyond behavioral task performance.

Enhancement of inhibitory control in a sample of preschoolers from poor homes after cognitive training in a kindergarten setting: Cognitive and ERP evidence

Cognitive Control (CC) is a central aspect of self-regulatory development, which can be modulated by individual differences, the quality of experiences in several developmental contexts (e.g., home, school, community), and cognitive interventions. In particular, associations between childhood poverty and cognitive and neural aspects of CC have also been documented in recent years. Less evidence is available regarding the brain areas influence by cognitive intervention in children from poor homes. In the present study, we examined the impact of a computerized, cognitive training that was implemented at a kindergarten on inhibitory control performance by cognitive and EEG methods. Children were trained weekly for 8 weeks and tested before and after the intervention using EEG recordings during a Go/NoGo task performance. Children in the intervention group (n = 24; 18 girls, mean age 5.32 ± 0.39 years) played games that tapped inhibitory control, working memory, and planning demands on a tablet, whereas those in the control group (n = 20; 7 girls, mean age 5.42 ± 0.27 years) played Internet free games with the same schedule. Electrophysiological measures related to performance of inhibitory control showed improvements only in the intervention group, and no differences were found in cognitive performance. Specifically, only the intervention group showed in increase in the frontal N2-effect; that is, there was larger differentiation between the amplitude of N2-NoGo and N2-Go in the post-test stage. These results show: (a) that the implemented intervention modulated the neural resources related to inhibitory control processes, and (b) it is possible to implement portable neural methodologies in school settings to enhance the evaluation of cognitive training interventions by adding an EEG component.

Does Transcranial Direct Current Stimulation Affect Post-stressor Intrusive Memories and Rumination? An Experimental Analogue Study

Deficits in cognitive control have been linked to intrusive memories after traumatic life events as well as rumination. However, causal relations are still unclear. Causality can be investigated by directly influencing a brain region associated with cognitive control via transcranial direct current stimulation (tDCS). In this study, we investigated the effects of tDCS over the left dorsolateral prefrontal cortex (dlPFC) on one aspect of cognitive control—resistance to proactive interference (PI)—as well as on intrusive memories and rumination. Using a between-subject design, we expected active tDCS to affect intrusive memories and rumination by influencing resistance to PI. N = 118 healthy individuals completed the modified California Verbal Learning Test twice, once without stimulation and once during 20-min tDCS (anodal, cathodal, or sham). Following tDCS, participants watched a trauma film; afterwards, intrusive memories and rumination were assessed. TDCS neither affected resistance to PI nor film-related intrusive memories or rumination. Furthermore, individuals with low resistance to PI did not experience more intrusive memories or rumination. These results question the role of the left dlPFC as well as the well-established link between resistance to PI and intrusive memories. Future studies are needed to replicate these findings and to address possible methodological shortcomings of this study.

Cognitive enhancement with Salience Network electrical stimulation is influenced by network structural connectivity

The Salience Network (SN) and its interactions are important for cognitive control. We have previously shown that structural damage to the SN is associated with abnormal functional connectivity between the SN and Default Mode Network (DMN), abnormal DMN deactivation, and impaired response inhibition, which is an important aspect of cognitive control. This suggests that stimulating the SN might enhance cognitive control. Here, we tested whether non-invasive transcranial direct current stimulation (TDCS) could be used to modulate activity within the SN and enhance cognitive control. TDCS was applied to the right inferior frontal gyrus/anterior insula cortex during performance of the Stop Signal Task (SST) and concurrent functional (f)MRI. Anodal TDCS improved response inhibition. Furthermore, stratification of participants based on SN structural connectivity showed that it was an important influence on both behavioural and physiological responses to anodal TDCS. Participants with high fractional anisotropy within the SN showed improved SST performance and increased activation of the SN with anodal TDCS, whilst those with low fractional anisotropy within the SN did not. Cathodal stimulation of the SN produced activation of the right caudate, an effect which was not modulated by SN structural connectivity. Our results show that stimulation targeted to the SN can improve response inhibition, supporting the causal influence of this network on cognitive control and confirming it as a target to produce cognitive enhancement. Our results also highlight the importance of structural connectivity as a modulator of network to TDCS, which should guide the design and interpretation of future stimulation studies.

Functional MRI in Macaque Monkeys during Task Switching

Nonhuman primates have proven to be a valuable animal model for exploring neuronal mechanisms of cognitive control. One important aspect of executive control is the ability to switch from one task to another, and task-switching paradigms have often been used in human volunteers to uncover the underlying neuronal processes. To date, however, no study has investigated task-switching paradigms in nonhuman primates during functional magnetic resonance imaging (fMRI). We trained two rhesus macaques to switch between arm movement, eye movement, and passive fixation tasks during fMRI. Similar to results obtained in human volunteers, task switching elicits increased fMRI activations in prefrontal cortex, anterior cingulate cortex, orbitofrontal cortex, and caudate nucleus. Our results indicate that the macaque monkey is a reliable model with which to investigate higher-order cognitive functioning such as task switching. As such, these results can pave the way for a detailed investigation of the neural basis of complex human behavior.SIGNIFICANCE STATEMENT Task switching is an important aspect of cognitive control, and task-switching paradigms have often been used to investigate higher-order executive functioning in human volunteers. We used a task-switching paradigm in the nonhuman primate during fMRI and found increased activation mainly in prefrontal areas (46, 45, frontal eye field, and anterior cingulate), in orbitofrontal area 12, and in the caudate nucleus. These data fit surprisingly well with previous human imaging data, proving that the monkey is an excellent model to study task switching with high spatiotemporal resolution tools that are currently not applicable in humans. As such, our results pave the way for a detailed interrogation of regions performing similar executive functions in humans and monkeys.

Preserved but Less Efficient Control of Response Interference After Unilateral Lesions of the Striatum.

Previous research on the neural basis of cognitive control processes has mainly focused on cortical areas, while the role of subcortical structures in cognitive control is less clear. Models of basal ganglia function as well as clinical studies in neurodegenerative diseases suggest that the striatum (putamen and caudate nucleus) modulates the inhibition of interfering responses and thereby contributes to an important aspect of cognitive control, namely response interference control. To further investigate the putative role of the striatum in the control of response interference, 23 patients with stroke-induced lesions of the striatum and 32 age-matched neurologically healthy controls performed a unimanual version of the Simon task. In the Simon task, the correspondence between stimulus location and response location is manipulated so that control over response interference can be inferred from the reaction time costs in incongruent trials. Results showed that stroke patients responded overall slower and more erroneous than controls. The difference in response times (RTs) between incongruent and congruent trials (known as the Simon effect) was smaller in the ipsilesional/-lateral hemifield, but did not differ significantly between groups. However, in contrast to controls, stroke patients exhibited an abnormally stable Simon effect across the reaction time distribution indicating a reduced efficiency of the inhibition process. Thus, in stroke patients unilateral lesions of the striatum did not significantly impair the general ability to control response interference, but led to less efficient selective inhibition of interfering responses.

Physical intensity of stimuli modulates motor inhibition by affecting response selection processes in right inferior frontal regions

Response inhibition is a central aspect of cognitive control. Yet, only recently the role of sensory mechanisms for response inhibition has been addressed and neurophysiological mechanisms are far from being understood. Here we ask in how far the physical intensity of stimuli is a relevant perceptual factor modulating motor inhibitory control. We investigated how different physical (objective) stimulus and the subjectively perceived stimulus magnitude modulated response inhibition and its neurophysiological correlates. To this end we used a somatosensory GO/NOGO task in combination with EEG recordings and applied temporal signal decomposition and source localization methods. The behavioral (false alarm) data clearly demonstrated that response inhibition performance was worse in the subjective and objective stimulation condition as compared to the reference stimulation condition with higher stimulus magnitude. Despite primary perceptual aspects were manipulated, neurophysiological correlates of lower-level perceptual and attentional selection processes did not explain effects on overt response inhibition behavior. Rather, neurophysiological processes at the response selection level were modulated. These were associated with activation differences in the right inferior frontal gyrus and suggest that “braking processes” enabling the inhibition of a to-be-executed motor response were modulated. The modulation of these braking processes depends on objective physical magnitude of incoming sensory information and not the subjectively perceived stimulus magnitude.

Optogenetic and chemogenetic approaches to manipulate attention, impulsivity and behavioural flexibility in rodents.

Studies manipulating neural activity acutely with optogenetic or chemogenetic intervention in behaving rodents have increased considerably in recent years. More often, these circuit-level neural manipulations are tested within an existing framework of behavioural testing that strives to model complex executive functions or symptomologies relevant to multidimensional psychiatric disorders in humans, such as attentional control deficits, impulsivity or behavioural (in)flexibility. This methods perspective argues in favour of carefully implementing these acute circuit-based approaches to better understand and model cognitive symptomologies or their similar isomorphic animal behaviours, which often arise and persist in overlapping brain circuitries. First, we offer some practical considerations for combining long-term, behavioural paradigms with optogenetic or chemogenetic interventions. Next, we examine how cell-type or projection-specific manipulations to the ascending neuromodulatory systems, local brain region or descending cortical glutamatergic projections influence aspects of cognitive control. For this, we primarily focus on the influence exerted on attentional and motor impulsivity performance in the (3-choice or) 5-choice serial reaction time task, and impulsive, risky or inflexible choice biases during alternative preference, reward discounting or reversal learning tasks.

Normal development of context processing using the AXCPT paradigm.

Context processing involves a flexible and continually updated representation of task relevant information and is a core aspect of cognitive control. The expectancy AX Continuous Performance Test (AXCPT) was designed to specifically measure context processing and has been widely applied to elucidate mechanisms of cognitive control and their impairments in conditions such as aging and schizophrenia. Here we present a large-sample, cross-sectional study of context processing aimed at characterizing its normal development from childhood to early adulthood (8 to 22 years old). We track the age-related changes in the standard AXCPT performance measures and also investigate their validity using detailed data-driven method. We show how critical maturational changes in context processing can be validly tracked from mid-adolescence onward with increasing reliance on preparatory, proactive strategies well into early adulthood. However, the early maturation from childhood into adolescence showed a sharp, two-fold discontinuity: while standard measures provide partially conflicting results suggesting an early worsening of proactive strategies, further analyses do not support their validity during this period. Our findings advocate the existence of multiple preparatory strategies that cannot be captured by indices that assume a simple dichotomy of proactive vs. reactive strategies. When evaluating context processing differences over development or in clinical populations, we advocate the explicit testing of the assumptions underlying standard AXCPT indices through complementary data-driven methods.

Reduced distractor interference during vagus nerve stimulation

Suppressing irrelevant information in decision making is an essential everyday skill. We studied whether this ability could be improved in epileptic patients during vagus nerve stimulation (VNS). VNS is known to increase norepinephrine (NE) in the brain. NE is thought to improve several aspects of cognitive control, including the suppression of irrelevant information. Nineteen epileptic VNS patients executed the Eriksen flanker task twice, both during on and off stimulation. Distractor interference was indexed by the congruency effect, a standard empirical marker of cognitive control. We found a reduced congruency effect during stimulation, which indicates an improved ability to suppress distractor interference. This effect was only found in patients that are clinically determined VNS-responders (n = 10). As VNS increases NE in VNS-responders, our finding suggests a beneficial role of NE in cognitive control. At the same time, it suggests that VNS does not only reduce seizure frequency in epileptic patients, but also improves cognitive control.

Persistent modification of cognitive control through attention training.

An important aspect of cognitive control is to direct attention towards relevant information and away from distracting information. This attentional modulation is at the core of several influential frameworks, but its trainability and generalisability remain unclear. To address this issue, two groups of subjects were invited to the lab on three consecutive days. On Day 2, they performed an arrow priming task which trained them to adopt an attentional bias towards (prime-attended group) or away from (prime-diverted group) a potentially conflicting prime. Direct generalisation of the attention training was measured by assessing task performance on the same task without the attentional manipulation directly after training (Day 2) and the next day (Day 3), and comparing it to baseline (Day 1). Performance on this direct transfer task showed a difference in attentional modulation between groups directly after training that persisted the next day. No cross-task generalisation was found to two other tasks that were closely or more remotely related to the trained task. Together, these results are in accordance with cognitive control frameworks that limit attentional modulation to the specific features of the trained task.

Cognitive Control, Semantic Processing, and Semantic Ambiguity Resolution in Individuals with Aphasia

Event Abstract Back to Event Cognitive Control, Semantic Processing, and Semantic Ambiguity Resolution in Individuals with Aphasia Wiltrud Fassbinder1*, Rebecca Hunting Pompon2, Mohammed Aldhoayan3, Hyun Seung Kim1, Hyunsoo Yoo4, Johannes Hüsing5, Kevin Dalziel6, Jeremy Mancini7 and Malcolm R. McNeil1 1 University of Pittsburgh, Communication Sciences and Disorders, United States 2 University of Delaware, Communication Science and Disorders, United States 3 University of Pittsburgh, Health Information Management, United States 4 The University of Texas at El Paso, Rehabilitation Sciences, United States 5 Universitätsklinikum Heidelberg, Koordinierungszentrum für Klinische Studien (KKS), Germany 6 VA Northern California Health Care System, Speech Language Pathology, United States 7 Jefferson University Hospitals, Thomas Jefferson University, United States INTRODUCTION Several imaging and lesion-based studies suggest that cognitive control plays an important role in semantic ambiguities resolution[1]. However, two recent behavioral studies indicate that such interference resolution may be more related to verbal semantic abilities than to cognitive control[2,3], with better semantic abilities resulting in more ambiguity interference[2]. While deficits in cognitive control are well documented in individuals with aphasia (IWA)[4,5,6], the effects of such deficits for ambiguity resolution have not been investigated in conjunction with semantic abilities. This study investigates how in IWA, cognitive control and lexical-semantic abilities contribute to comprehension efficiency and success in ambiguity resolution. It was predicted that for IWA, deficits in cognitive control result in increased ambiguity interference and decreased accuracy, whereas deficits in lexical-semantic processing result in decreased ambiguity interference, on a sentence comprehension task (SCT) requiring lexical ambiguity resolution. PROCEDURES Ninety-five IWA completed all study tasks. Cognitive control was indexed as the RT ratio of incongruent/neutral items in a picture-word interference task (PWI ratio). Lexical semantic processing was measured as accuracy in a category judgment task (CJ accuracy). On the SCT, participants read sentences with a disambiguating verb and an ambiguous object, followed by a probe word related to alternative meaning of the ambiguous object (He drank the port today – docks)[7]. In the control condition, ambiguous objects were replaced with unambiguous words. All timing measures were modeled in linear mixed effect models, and accuracy was fitted using logistic mixed regression models[8]. Subjects and items were entered as random effects (including intercepts and slopes[9]), and ambiguity (ambiguous/control), PWI ratio, and CJ accuracy as fixed effects. RESULTS RT IWA with higher PWI ratios responded faster in the SCT than those with lower ratios (95% CI [-14.4 – -2.8]). Main effects for ambiguity (95% CI [-.8 – -.04]) and lexical-semantic processing (95% CI [-1.4 – .2]) were modulated by an interaction (95% CI [.2 – 1]): Ambiguity interference was only evident in IWA with higher CJ accuracy (see Figure 1). Accuracy Ambiguous items were less accurate than unambiguous items (95% CI [.2– 1]). DISCUSSION Cognitive Control: The lack of relationship between PWI interference and SCT ambiguity for RT and accuracy suggests that different aspects of cognitive control are required in the two tasks6: In the PWI task, inhibition is task-driven and mainly proactive, whereas in the SCT inhibition is mainly reactive. However, higher PWI interference is associated with faster judgments, suggesting that it reflects an underlying cognitive factor relevant to processing efficiency, possibly processing speed. Further analyses of available data will examine this possibility. Lexical-semantic processing: Faster lexical semantic processing was associated with faster RTs and more ambiguity interference, consistent with the hypothesis that better semantic processing results in faster activation of alternative meanings, causing more interference[4]. However, differences in CJ accuracy did not affect SCT accuracy, suggesting that this interference was successfully resolved. For individuals with poorer lexical-semantic processing, RTs were slower, and there was less/no ambiguity interference, suggesting that competing word meanings were not sufficiently re-activated to interfere with the decision time or comprehension success. Figure 1