The Stroop effect and mental imagery.

The classic Stroop task is very simple: you have to name the color of words printed on a page. If these words are color words (like "red" or "blue"), where the color named and the color it is printed in are different (say, "red" printed in blue), the reaction time increases significantly. My aim is to argue that the existing psychological explanations of the Stroop effect need to be supplemented. The Stroop effect is not exclusively about access to motor control. It is also, to a large extent, about interferences in perceptual processing. To put it briefly, reading the color word triggers-laterally and automatically-visual imagery of the color and this interferes with the processing of the perceived color of the word. In other words, the Stroop effect is to a large extent a sensory phenomenon, and it has less to do with attention, conflict monitoring, or other higher-level phenomena.

A color-digit Stroop task shows numerical influence on numerosity processing.

The numerical Stroop task involves presenting participants with two digits that differ in physical size and numerical value and asking them to report which digit had the larger size or value while ignoring the other dimension. Previous studies show that participants have difficulty ignoring the irrelevant dimension and thus have implications on the automaticity of numerical processing. The present study investigates the automatic influence of numerical value on numerosity processing in a novel Stroop-like task. In two experiments, participants were presented with digits made of colored stripes and asked to identify the number of different colors. In both experiments, interference and facilitation effects were found, supporting the automaticity of symbolic number processing and its influence on numerosity processing. These findings expand upon previous research on numerical as well as counting Stroop tasks, and have potential implications for studying interference and basic numerical processing in children and clinical populations.

Distributional analyses reveal the polymorphic nature of the Stroop interference effect: It's about (response) time.

The study addressed the still-open issue of whether semantic (in addition to response) conflict does indeed contribute to Stroop interference (which along with facilitation contributes to the overall Stroop effect also known as Congruency effect). To this end, semantic conflict was examined across the entire response time (RT) distribution (as opposed to mean RTs). Three (out of four) reported experiments, along with cross-experimental analyses, revealed that semantic conflict was absent in the participants' faster responses. This result characterizes Stroop interference as a unitary phenomenon (i.e., driven uniquely by response conflict). When the same participants' responses were slower, Stroop interference became a composite phenomenon with an additional contribution of semantic conflict that was statistically independent of both response conflict and facilitation. While the present findings allow us to account for the fact that semantic conflict has not been consistently found in past studies, further empirical and theoretical efforts are still needed to explain why exactly it is restricted to longer responses. Indeed, since neither unitary nor composite models can account for this polymorphic nature of Stroop interference on their own, the implications for the current state of theory are outlined.

Assessment of ADHD Subtypes Using Motion Tracking Recognition Based on Stroop Color-Word Tests.

Attention-Deficit/Hyperactivity Disorder (ADHD) is a neurodevelopmental disorder known for its significant heterogeneity and varied symptom presentation. Describing the different subtypes as predominantly inattentive (ADHD-I), combined (ADHD-C), and hyperactive-impulsive (ADHD-H) relies primarily on clinical observations, which can be subjective. To address the need for more objective diagnostic methods, this pilot study implemented a Microsoft Kinect-based Stroop Color-Word Test (KSWCT) with the objective of investigating the potential differences in executive function and motor control between different subtypes in a group of children and adolescents with ADHD. A series of linear mixture modeling were used to encompass the performance accuracy, reaction times, and extraneous movements during the tests. Our findings suggested that age plays a critical role, and older subjects showed improvements in KSWCT performance; however, no significant divergence in activity level between the subtypes (ADHD-I and ADHD-H/C) was established. Patients with ADHD-H/C showed tendencies toward deficits in motor planning and executive control, exhibited by shorter reaction times for incorrect responses and more difficulty suppressing erroneous responses. This study provides preliminary evidence of unique executive characteristics among ADHD subtypes, advances our understanding of the heterogeneity of the disorder, and lays the foundation for the development of refined and objective diagnostic tools for ADHD.

Cursor movements to targets labelled "stop": a kinematic analysis.

The label 'Stop' potentially generates conflict-signifying important corrective action, or a warning not to touch. To examine potential conflict between an incongruent label (i.e. STOP) and an imperative command (i.e. MOVE!), 18 participants used a computer mouse to move a crosshair cursor to targets with superimposed labels. Trials systematically varied Imperative (blank or MOVE!), Label (+GO + or STOP) and movement Distance. Kinematic analyses examined response latency, movement duration and accuracy. Incongruent labels had little impact upon response latencies, but they affected cursor deceleration and the variability of cursor placement. Although reading is assumed to be obligatory, the impact of written labels is not immediate, instead affecting cursor deceleration. Indeed, responses to controls labelled STOP were less accurate than those labelled + GO+. As labelled interfaces can create error versus command confusions, enhancing the discriminability of controls to afford more obvious visible cues as to method of use is recommended. Practitioner summary: Emergency stop and shutdown controls can cause response conflict as their labels signify both urgent corrective actions and 'don't touch'. Response conflict caused by confusing superimposed labels is resolved as cursors near the target control and may result in reduced movement accuracy. Prior warnings may influence resolution of response conflict. Abbreviations: Hz: Hertz; M: Mean; ms: millisecond; mm: millimetre; S: second; SD: Standard Deviation; SE: Standard Error; USB: Universal Serial Bus.

Limitations of cognitive control on emotional distraction - Congruency in the Color Stroop task does not modulate the Emotional Stroop effect.

Emotional information receives prioritized processing over concurrent cognitive processes. This can lead to distraction if emotional information has to be ignored. In the cognitive domain, mechanisms have been described that allow control of (cognitive) distractions. However, whether similar cognitive control mechanisms also can attenuate emotional distraction is an active area of research. This study asked whether cognitive control (triggered in the Color Stroop task) attenuates emotional distraction in the Emotional Stroop task. Theoretical accounts of cognitive control, and the Emotional Stroop task alike, predict such an interaction for tasks that employ the same relevant (e.g., color-naming) and irrelevant (e.g., word-reading) dimension. In an alternating-runs design with Color and Emotional Stroop tasks changing from trial to trial, we analyzed the impact of proactive and reactive cognitive control on Emotional Stroop effects. Four experiments manipulated predictability of congruency and emotional stimuli. Overall, results showed congruency effects in Color Stroop tasks and Emotional Stroop effects. Moreover, we found a spillover of congruency effects and emotional distraction to the other task, indicating that processes specific to one task impacted to the other task. However, Bayesian analyses and a mini-meta-analysis across experiments weigh against the predicted interaction between cognitive control and emotional distraction. The results point out limitations of cognitive control to block off emotional distraction, questioning views that assume a close interaction between cognitive control and emotional processing.

Incompatibility Influences Cursor Placement When Pointing to Images of Cups.

OBJECTIVE: As images are used within graphical user interfaces to signify menu selection, it is important to understand how image properties can influence cursor placement online. BACKGROUND: Objects have multiple dimensions that create potential ambiguity and Stroop-like confusions for the operator if a previously habitual response conflicts with the required response. METHODS: To examine the impact of compatibility and other contextual factors, 41 participants used a computer Mouse or touch screen to place the cursor upon images of full or empty cups that varied in size, and direction of handle. RESULTS: Cursor placements took longer using the Mouse than touch screen. Although participants were placing the cursor on images, the size of the cup, whether it was empty or full, and the handle orientation interacted in their effects upon response duration and cursor placement. The effects of cup size reversed for empty cups or those with incompatible handles. CONCLUSION: Context can influence cursor placement. Perceived spillability influenced precision requirements, and the cup handle can serve as target or a flanking distractor. APPLICATION: Image content can influence screen hotspots. As performance can change with cup spillability, this bodes well for attempts to detect intent from cursor trajectories.

Exhaustion disorder and altered brain activity in frontal cortex detected with fNIRS.

Patients with stress-related Exhaustion Disorder (ED) have problems with memory and executive function. These problems have been associated with deviant activity in prefrontal cortex (PFC). We investigated cognitive performance and functional activity in the PFC during prolonged mental activity in patients with ED (n = 20, 16 women) with a mean duration since diagnosis of 46 ± 23 months in comparison to healthy individuals (n = 20, 12 women). A block of six neuropsychological tests was performed in a sequence that was repeated once. The brain imaging technique, functional near infrared spectroscopy (fNIRS) was used for all tests. There were no differences between the groups in terms of changes over time, i.e. difference between first and second test block. In the Stroop-Simon test, the controls showedhigher functional activity in the frontal cortex. In the left ventrolateral PFC, we observed an increased activity in controls in the incongruent compared to the congruent trials, whereas no changes were detected in the ED patient group. During processing speed tasks, only ED patients showed higher functional activity in right dorsolateral PFC. The ED patients reported lower subjective energy level and they also performed less well on a mental control task compared to healthy individuals. In conclusion, ED patients showed altered functional activity compared to controls, indicating that ED patients process information differently in the prefrontal cortex, but the functional activity did not change during the 2½ hr procedure, as revealed by the test-retest design. Lay summary In this paper we show that patient with exhaustion disorder have a reduced functional activity in the prefrontal cortex. This functional activity was not affected by 2.5 hours mental activity.

Cognitive control and emotional response in attention-deficit/ hyperactivity disorder comorbidity with disruptive, impulse-control, and conduct disorders.

BACKGROUND: This study investigated cognitive and emotional functioning in children and adolescents with attention-deficit/hyperactivity disorder (ADHD) and disruptive, impulse-control, and conduct disorders (DICCD). METHODS: Thirty patients with ADHD, 26 with DICCD, 22 with ADHD+DICCD were recruited from the outpatient department of Shanghai Changning Mental Health Center, plus 20 healthy controls (HC). Differences between the groups in cognitive and emotional functioning were examined using Golden's Stroop and Emotional Stroop tests. For Emotional Stroop Mean reaction time (RT) of positive word (POS) and negative word (NEG) with color congruence (C) or incongruence (I) were recorded as POS-C, POS-I, NEG-C and NEG-I, respectively. RESULTS: For Golden's interference scores (IGs), both errors and RTs in the ADHD group were higher than in the other groups. Longer mean RTs of POS-C, POS-I, NEG-C and neural word (NEU) of the ADHD group, and NEG-I of ADHD+DICCD and DICCD groups were observed compared to HC. After 12 weeks of methylphenidate treatment, differences between ADHD subgroups and HC on Golden's Stroop RT disappeared, but differences in Golden's Stroop errors and Emotional Stroop mean RTs remained. The ADHD+DICCD group showed longer mean RTs in NEG-C, NEG-I and NEU of the Emotional Stroop test than the ADHD group. CONCLUSIONS: Our study shows that regardless of emotional responding, deficit in cognitive control is the core symptom of ADHD. However, emotionally biased stimuli may cause response inhibitory dysfunction among DICCD with callous-unemotional traits, and the comorbidity of ADHD and DICCD tends to account for the negative emotional response characteristic of DICCD. These deficits may be eliminated by medication treatment in ADHD, but not the ADHD with comorbid DICCD. Our results support the notion that ADHD with comorbid DICCD is more closely related to DICCD than to ADHD.

Carbohydrate ingestion attenuates cognitive dysfunction following long-duration exercise in the heat in humans.

INTRODUCTION: To determine if electrolyte or carbohydrate supplementation vs. water would limit the magnitude of dehydration and decline in cognitive function in humans following long-duration hyperthermic-exercise. METHODS: 24 subjects performed 3 visits of 2 h walking (3mph/7% grade) in an environmental chamber (33 °C/10% relative humidity). In random order, subjects consumed water (W), electrolytes (Gatorade Zero; E), or electrolytes+carbohydrates (Gatorade; E+C). Throughout exercise (EX), subjects carried a 23 kg pack and drank ad-libitum. Pre-and post-EX, body mass (BM) and plasma osmolality (pOsm) were measured. Physiological Strain Index (PSI) and core temperature (TC) were recorded every 15 min. Plasma glucose (GLU) was measured every 30 min. Cognitive processing (SCWT) was measured post-EX and compared to baseline (BL). A subset of 8 subjects performed a normothermic (N) protocol (21 °C/ambient humidity) to ascertain how the exercise stimulus influenced hydration status and cognition without heat. RESULTS: There were no significant differences between fluid conditions (W, E, E+C) for BM loss (Δ2.5 ± 0.2, 2.5 ± 0.2, 2.3 ± 0.2 kg), fluid consumption (1.9 ± 0.2, 1.9 ± 0.2, 1.8 ± 0.2L), pOsm (Δ1.5 ± 2.7, 2.2 ± 2.4, 2.0 ± 1.5 mmol/L), peak-PSI (7.5 ± 0.4, 7.0 ± 0.6, 7.9 ± 0.5), and peak-TC (38.7 ± 0.1, 38.6 ± 0.2, 38.8 ± 0.2 °C). GLU decreased significantly in W and E, whereas it increased above BL in E+C at 60, 90, and 120 min (P < 0.05). Compared to BL values (43.6 ± 26 ms), SCWT performance significantly decreased in all conditions (463 ± 93, 422 ± 83, 140 ± 52 ms, P < 0.05). Importantly, compared to W and E, the impairment in SCWT was significantly attenuated in E+C (P < 0.05). As expected, when compared to the heat-stress protocol (W, E, E+C), N resulted in lower BM loss, fluid consumption, and peak-PSI (1.1 ± 0.1 kg, 1.2 ± 0.7L, 4.8, respectively), and improved SCWT performance. CONCLUSIONS: These data are the first to suggest that, independent of supplementation variety, cognitive processing significantly decreases immediately following long-duration exercise in the heat in healthy humans. Compared to water and fluids supplemented with only electrolytes, fluids supplemented with carbohydrates significantly blunts this decrease in cognitive function.

Decline in attentional inhibition among migraine patients: an event-related potential study using the Stroop task.

BACKGROUND: As a disorder of brain dysfunction, migraine has been associated with cognitive decline. However, no consistent results with respect to the attention function in migraineurs have been found, and the relationship between attentional inhibition and migraine is also unclear. In this study, the attentional inhibition function was evaluated using event-related potentials (ERPs) while migraine patients and healthy controls were performing the color-word Stroop task. METHODS: In this study, 75 migraine patients and 41 age-, gender-, and education-matched healthy controls were enrolled. The Stroop task was performed, and both behavioral and ERP data were analyzed. RESULTS: As to the behavioral data, the migraine group had a longer reaction time compared to the control group, but no difference in Stroop effect was observed. With respect to ERP components, the amplitudes of both early and late medial frontal negativity (MFN) were decreased in the migraine group. Additionally, obvious differences in the early MFN and sustained potential (SP) amplitudes were found between patients with and without allodynia. CONCLUSIONS: At the behavioral level, migraine patients exhibited decreased executive ability but no obvious decline in inhibition. By contrast, a decline in attentional inhibition during the migraine interictal phase was confirmed by the analysis of ERP components, mainly those associated with changes in the conflict-monitoring stage, independent of confounding factors such as age, education, medication and mood disorders. Migraine patients with allodynia exhibited some significant differences in early MFN and SP compared to those without, supporting the hypothesis that migraine chronification aggravates the decline in attentional inhibition.

Causal underpinnings of working memory and Stroop interference control: Testing the effects of anodal and cathodal tDCS over the left DLPFC.

By means of transcranial direct current stimulation applied to the left dorsolateral prefrontal cortex, we investigated the causal role of increased or decreased excitability of this brain region for two facets of executive functions: working memory and Stroop interference control. We tested 1) whether anodal tDCS of the left DLPFC enhances working memory 15 minutes after termination of stimulation and in the absence of direct task practice under stimulation; 2) whether anodal tDCS of the left DLPFC enhances interference control, as evidenced by Stroop performance and Stroop sequence effects; and 3) whether cathodal tDCS leads to compromised executive functioning compared to anodal stimulation. In a between-subject design with 88 healthy psychology students, we compared the impact of anodal and cathodal stimulation against a sham condition, on performance on a Stroop task (during active stimulation) and on an n-back task (completed 15 minutes after active stimulation ended). We found significantly enhanced accuracy in the n-back task after anodal stimulation compared with sham, as well as speeded reactions in the Stroop tasks independent of trial type. By contrast, we found no modulation of Stroop interference effects or Stroop sequence effects. No inhibitory effects of cathodal stimulation were observed. These results support the causal role of the left DLPFC in working memory but lend no support to its involvement in Stroop interference control.

Effects of chronic pain history on perceptual and cognitive inhibition.

Measures of sensory and cognitive inhibition were obtained from university students with and without a history of chronic pain. The form of sensory inhibition measured was diffuse noxious inhibitory controls (DNIC), the capacity of a painful stimulus to reduce the subjective intensity of a second stimulus delivered to a remote body site. To measure cognitive inhibition, the Stroop effect was used. Participants with a history of chronic pain showed less DNIC (i.e., less sensory inhibition) than the healthy controls, but had a smaller Stroop effect (indicating greater cognitive inhibition). The fact that chronic pain history is associated with opposite changes in these two measures casts doubt on the view that the two inhibitory processes are related. Scores on each experimental measure were equivalent in pain-history subjects with ongoing chronic pain and those whose chronic pain had resolved. This equivalence suggests that chronic pain in childhood or adolescence may have lingering effects on sensory and cognitive inhibition.

Pupillometric contributions to deciphering Stroop conflicts.

The Stroop task gives rise to two major conflicts: the task conflict (respond to the color vs. read the word) and the information conflict that can result from the stimulus-response compatibility (SRC; difference between two responses) or from the stimulus-stimulus compatibility (SSC; difference between the two contradictive pieces of information). We conducted a two-to-one Stroop experiment (i.e., two colors are mapped to one response key) and measured reaction time and pupil dilation. The results showed clear evidence for informational conflict composed of both the SRC and SSC. In addition, pupil indications for task conflict appeared earlier than indications for both the SSC and the SRC, in line with the theory regarding task conflict.

Psycholinguistic Investigation of the Immediate Interpretation of Plural Nouns in the Scope of Sentential Negation in Polish.

The number meaning of grammatically plural nouns is to some extent context sensitive. In negative sentences, plural nouns typically receive an inclusive reading referring to any number of individuals (one or many). This contrasts with their more frequent exclusive reading referring to a group of two or more individuals. The present study investigated whether a plural noun in a negative sentence is treated as inclusive immediately when it is encountered or whether this interpretation is delayed. In an experiment using a technique based on a numerical variant of the Stroop effect (Berent et al. in J Mem Lang 53:342-358, 2005. https://doi.org/10.1016/j.jml.2005.05.002 ; Patson and Warren in J Exp Psychol Learn Mem Cogn 36(3):782-789, 2010. https://doi.org/10.1037/a0018783 ), participants counted visually presented singular and plural Polish nouns embedded in either affirmative or negative sentences. The nouns were displayed once or as two copies. Plural nouns were easier to count when they were repeated twice on the screen than when only one copy was displayed. For singular nouns this pattern was reversed and the effect was weaker. Crucially, no difference was found for plural nouns appearing in affirmative and negative sentences. This indicated that an inclusive ("one or more") reading of plural nouns in the scope of sentential negation was not immediate. The results are in line with past research suggesting that the semantic processing of a negative sentence may proceed in two phases (Fischler et al. in Psychophysiology 20(4):400-409, 1983. https://doi.org/10.1111/j.1469-8986.1983.tb00920.x ; Kaup et al. in J Pragmat 38:1033-1050, 2006. https://doi.org/10.1016/j.pragma.2005.09.012 ; Lüdtke et al. in J Cogn Neurosci 20(8):1355-1370, 2008. https://doi.org/10.1162/jocn.2008.20093 ; Spychalska in Proceedings of the 2011 ESSLLI student session, 2011).

The emergence of automaticity in reading: Effects of orthographic depth and word decoding ability on an adjusted Stroop measure.

How long does it take for word reading to become automatic? Does the appearance and development of automaticity differ as a function of orthographic depth (e.g., French vs. English)? These questions were addressed in a longitudinal study of English and French beginning readers. The study focused on automaticity as obligatory processing as measured in the Stroop test. Measures of decoding ability and the Stroop effect were taken at three time points during first grade (and during second grade in the United Kingdom) in 84 children. The study is the first to adjust the classic Stroop effect for inhibition (of distracting colors). The adjusted Stroop effect was zero in the absence of reading ability, and it was found to develop in tandem with decoding ability. After a further control for decoding, no effects of age or orthography were found on the adjusted Stroop measure. The results are in line with theories of the development of whole word recognition that emphasize the importance of the acquisition of the basic orthographic code.

Don't believe everything you hear: Routine validation of audiovisual information in children and adults.

Previous research has shown that the validation of incoming information during language comprehension is a fast, efficient, and routine process (epistemic monitoring). Previous research on this topic has focused on epistemic monitoring during reading. The present study extended this research by investigating epistemic monitoring of audiovisual information. In a Stroop-like paradigm, participants (Experiment 1: adults; Experiment 2: 10-year-old children) responded to the probe words correct and false by keypress after the presentation of auditory assertions that could be either true or false with respect to concurrently presented pictures. Results provide evidence for routine validation of audiovisual information. Moreover, the results show a stronger and more stable interference effect for children compared with adults.

Feasibility of Smartphone-Based Testing of Interference in Parkinson's Disease.

BACKGROUND: Interference refers to learned associations and established behaviors "interfering" with response to new material. It forms a core pillar of executive functions, which are commonly affected in Parkinson's disease (PD). Cognitive interference test (CIT) forms part of a smartphone application designed for ambulatory assessment in PD. OBJECTIVE: The aims of this study were to establish that CIT could effectively demonstrate interference and would perform comparably to the Stroop Color-Word Test Victoria version (VST) despite PD-related motor impairment. METHODS: Ninety-nine patients with PD were recruited. Initial evaluation included CIT, VST, Montreal cognitive assessment (MOCA), and Movement Disorders Society-sponsored revision of the -Unified Parkinson's Disease Rating Scale (MDS-UPDRS-III). A group of patients underwent repeat assessment within 2 weeks. Thirty-four healthy controls were recruited for comparison. RESULTS: Patients' mean age was 66.2 years, disease duration was 8.7 years, on-state MDS-UPDRS-III was 22, and MOCA total score was 27. CIT effectively generated interference, whereby the total time taken to complete the incongruent task was 20% longer compared to that of the baseline task. CIT key test items demonstrated convergent validity to VST (r = 0.478-0.644, p < 0.0001) and satisfactory repeatability (intraclass correlation coefficient 0.46-0.808, p ≤ 0.0002). Performance on key CIT test parameters deteriorated with increasing age (r = 0.225-0.478, p < 0.01) and MDS-UPDRS-III total score (r = 0.354-0.481, p < 0.0001). When compared to controls and patients with less motor impairment, patients MDS-UPDRS-III > 30 took longer to complete CIT and VST and had lower MOCA-attention sub-score, implying that the degree of motor impairment could not be the sole explanation for reduced CIT performance. CONCLUSIONS: We established that despite motor impairment, the novel approach of using smartphone technology to test interference in PD patients is feasible.

Stimulation of subgenual cingulate area decreases limbic top-down effect on ventral visual stream: A DBS-EEG pilot study.

Deep brain stimulation (DBS) of the subgenual cingulate gyrus (area CG25) is beneficial in treatment resistant depression. Though the mechanisms of action of Cg25 DBS remain largely unknown, it is commonly believed that Cg25 DBS modulates limbic activity of large networks to achieve thymic regulation of patients. To investigate how emotional attention is influenced by Cg25 DBS, we assessed behavioral and electroencephalographic (EEG) responses to an emotional Stroop task in 5 patients during ON and OFF stimulation conditions. Using EEG source localization, we found that the main effect of DBS was a reduction of neuronal responses in limbic regions (temporal pole, medial prefrontal and posterior cingulate cortices) and in ventral visual areas involved in face processing. In the dynamic causal modeling (DCM) approach, the changes of the evoked response amplitudes are assumed to be due to changes of long range connectivity induced by Cg25 DBS. Here, using a simplified neural mass model that did not take explicitly into account the cytoarchitecture of the considered brain regions, we showed that the remote action of Cg25 DBS could be explained by a reduced top-down effective connectivity of the amygdalo-temporo-polar complex. Overall, our results thus indicate that Cg25 DBS during the emotional Stroop task causes a decrease of top-down limbic influence on the ventral visual stream itself, rather than a modulation of prefrontal cognitive processes only. Tuning down limbic excitability in relation to sensory processing might be one of the biological mechanisms through which Cg25 DBS produces positive clinical outcome in the treatment of resistant depression.

Evidence accumulation in the integrated and primed Stroop tasks.

We report distributional analyses of response times (RT) in two variants of the color-word Stroop task using manual keypress responses. In the classic Stroop task, in which the color and word dimensions are integrated into a single stimulus, the Stroop congruence effect increased across the quantiles. In contrast, in the primed Stroop task, in which the distractor word is presented ahead of colored symbols, the Stroop congruence effect was manifested solely as a distributional shift, remaining constant across the quantiles. The distributional-shift pattern mirrors the semantic-priming effect that has been reported in semantic categorization tasks. The results are interpreted within the framework of evidence accumulation, and implications for the roles of task conflict and informational conflict are discussed.