Individual Differences in Verbal and Spatial Stroop Tasks: Interactive Role of Handedness and Domain

Not All Stroop-Type Tasks Are Alike: Assessing the Impact of Stimulus Material, Task Design, and Cognitive Demand via Meta-analyses Across Neuroimaging Studies

The Stroop effect is one of the most often studied examples of cognitive conflict processing. Over time, many variants of the classic Stroop task were used, including versions with different stimulus material, control conditions, presentation design, and combinations with additional cognitive demands. The neural and behavioral impact of this experimental variety, however, has never been systematically assessed. We used activation likelihood meta-analysis to summarize neuroimaging findings with Stroop-type tasks and to investigate whether involvement of the multiple-demand network (anterior insula, lateral frontal cortex, intraparietal sulcus, superior/inferior parietal lobules, midcingulate cortex, and pre-supplementary motor area) can be attributed to resolving some higher-order conflict that all of the tasks have in common, or if aspects that vary between task versions lead to specialization within this network. Across 133 neuroimaging experiments, incongruence processing in the color-word Stroop variant consistently recruited regions of the multiple-demand network, with modulation of spatial convergence by task variants. In addition, the neural patterns related to solving Stroop-like interference differed between versions of the task that use different stimulus material, with the only overlap between color-word, emotional picture-word, and other types of stimulus material in the posterior medial frontal cortex and right anterior insula. Follow-up analyses on behavior reported in these studies (in total 164 effect sizes) revealed only little impact of task variations on the mean effect size of reaction time. These results suggest qualitative processing differences among the family of Stroop variants, despite similar task difficulty levels, and should carefully be considered when planning or interpreting Stroop-type neuroimaging experiments.

The Stroop legacy: A cautionary tale on methodological issues and a proposed spatial solution

The Stroop task is a seminal paradigm in experimental psychology, so much that various variants of the classical color-word version have been proposed. Here we offer a methodological review of them to emphasize the importance of designing methodologically rigorous Stroop tasks. This is not an end by itself, but it is fundamental to achieve adequate measurement validity, which is currently hindered by methodological heterogeneity and limitations. Among the several Stroop task variants in the literature, our methodological overview shows that the spatial Stroop task is not only a potentially methodologically adequate variant, which can thus assure measuring the Stroop effect with the required validity, but it might even allow researchers to overcome some of the methodological limitations of the classical paradigm due to its use of verbal stimuli. We thus focused on the spatial Stroop tasks in the literature to verify whether they really exploit such inherent potentiality. However, we show that this was generally not the case because only a few of them (1) are purely spatial, (2) ensure both all the three types of conflicts/facilitations (at the stimulus, response, and task levels) and the dimensional overlaps considered fundamental for yielding a complete Stroop effect according to the multiple loci account and Kornblum's theory, respectively, and (3) controlled for low-level binding and priming effects that could bias the estimated Stroop effect. Based on these methodological considerations, we present some examples of spatial Stroop tasks that, in our view, satisfy such requirements and, thus, ensure producing complete Stroop effects.

Unveiling the cognitive network organization through cognitive performance

The evaluation of cognitive functions interactions has become increasingly implemented in the cognition exploration. In the present study, we propose to examine the organization of the cognitive network in healthy participants through the analysis of behavioral performances in several cognitive domains. Specifically, we aim to explore cognitive interactions profiles, in terms of cognitive network, and as a function of participants' handedness. To this end, we proposed several behavioral tasks evaluating language, memory, executive functions, and social cognition performances in 175 young healthy right-handed and left-handed participants and we analyzed cognitive scores, from a network perspective, using graph theory. Our results highlight the existence of intricate interactions between cognitive functions both within and beyond the same cognitive domain. Language functions are interrelated with executive functions and memory in healthy cognitive functioning and assume a central role in the cognitive network. Interestingly, for similar high performance, our findings unveiled differential organizations within the cognitive network between right-handed and left-handed participants, with variations observed both at a global and nodal level. This original integrative network approach to the study of cognition provides new insights into cognitive interactions and modulations. It allows a more global understanding and consideration of cognitive functioning, from which complex behaviors emerge.

Both direction and degree of handedness as influential factors in rumination

There is contradictory evidence on the influence of handedness on depression and anxiety. However, few studies have investigated the relationship between handedness and rumination, which is robustly associated with both depression and anxiety. This study aimed to examine the influence of direction and consistency of handedness on rumination, considering four different classifications of handedness. The study sample included 406 participants (282 females) who attended an online survey and answered a demographic questionnaire, the Edinburgh Handedness Inventory, the Ruminative Response Scale, and the second edition of the Beck Depression Inventory. Considering four different classifications of handedness, a series of one-way ANOVAs was conducted to investigate any differences between the handedness groups. Besides, linear regression models were used to predict depression or rumination scores among the whole study sample, left-handers, and right-handers. Consistency of handedness predicted rumination among right-handers (but not left-handers), with a direct association between consistency and brooding/total rumination scores. Also, consistent left-handers and consistent right-handers showed higher brooding scores than inconsistent right-handers. Overall, the results supported the significant influence of both direction and consistency of handedness on individual differences in rumination and suggested consistent- and left-handedness as perpetuating factors for ruminative response style.

Top-down control of exogenous attentional selection is mediated by beta coherence in prefrontal cortex

Salience-driven exogenous and goal-driven endogenous attentional selection are two distinct forms of attention that guide selection of task-irrelevant and task-relevant targets in primates. During conflict i.e, when salience and goal each favor the selection of different targets, endogenous selection of the task-relevant target relies on top-down control. Top-down attentional control mechanisms enable selection of the task-relevant target by limiting the influence of sensory information. Although the lateral prefrontal cortex (LPFC) is known to mediate top-down control, the neuronal mechanisms of top-down control of attentional selection are poorly understood. Here, using a two-target free-choice luminance-reward selection task, we demonstrate that visual-movement neurons and not visual neurons or movement neurons encode exogenous and endogenous selection. We then show that coherent-beta activity selectively modulates mechanisms of exogenous selection specifically during conflict and consequently may support top-down control. These results reveal the VM-neuron-specific network mechanisms of attentional selection and suggest a functional role for beta-frequency coherent neural dynamics in the modulation of sensory communication channels for the top-down control of attentional selection.

Does the Degree and/or Direction of Handedness in Children With Developmental Coordination Disorder Influence Motor and Cognitive Performance? A Pilot Study

Research has shown that nonright-handedness in children with developmental coordination disorder (DCD) is associated with poorer motor and cognitive performance. This study investigated the influence of degree and direction of handedness on performance using the Home Handedness Questionnaire, the Hit-the-Dot test, the Movement Assessment Battery for Children, and the digital Trail-Making Test. Eighteen children with DCD and 21 typically developing children aged 8–12 years participated in this study. The distribution of degree and direction of handedness in the group of DCD children were not different from that found in the typically developing group. In the Hit-the-Dot test, typically developing children significantly performed better than children with DCD, no matter which hand was dominant or to which degree. A significant inconsistent-handed advantage in the subdomain balance was found for children with DCD. Inconsistent handedness also seems to be an advantage for children with DCD on the digital Trail-Making Test performance. The relationship between the subcategories of the Movement Assessment Battery for Children and the digital Trail-Making Test part B is stronger for consistent than for inconsistent handedness. Our findings suggest that children with DCD and inconsistent handedness might benefit from greater crosstalk across hemispheres. In addition, these predispositions can be reinforced or discouraged throughout development and via occupational therapy.

Behavioral response bias and event-related brain potentials implicate elevated incentive salience attribution to alcohol cues in emerging adults with lower sensitivity to alcohol

AIMS

This study used a behavioral approach-avoidance task including images of alcoholic beverages to test whether low sensitivity to alcohol (LS) is a phenotypical marker of a dispositional propensity to attribute bottom-up incentive value to naturally conditioned alcohol cues.

DESIGN, SETTING AND PARTICIPANTS

Experimental study with a measured individual difference variable at a university psychology laboratory in Missouri, MO, USA. Participants were 178 emerging adults (aged 18-20 years) varying in self-reported sensitivity to alcohol's acute effects.

MEASUREMENTS

Participants completed the alcohol approach-avoidance task while behavior (response time; RT) and the electroencephalogram (EEG) were recorded. Stimulus-locked event-related potentials (ERPs) provided indices of integrated (top-down and bottom-up) stimulus incentive value (P3 amplitude) and conflict between top-down task demands and bottom-up response propensities (N450 amplitude).

FINDINGS

Linear mixed models showed faster RT for 'alcohol-approach' relative to 'alcohol-avoid' trials for lower-sensitivity (LS) [mean_D  ± standard error_D (M_D  ± SE_D ) = 29.51 ± 9.74 ms, t₍₃₂₈₎  = 3.03, P = 0.003] but not higher-sensitivity (HS) individuals (M_D  ± SE_D  = 2.27 ± 9.33 ms, t₍₃₂₈₎  = 0.243, P = 0.808). There was enhanced N450 amplitude (response conflict) for alcohol-avoid relative to alcohol-approach trials for LS participants (M_D  ± SE_D  = 0.811 ± 0.198 μV, Z = 4.108, P < 0.001) and enhanced N450 amplitude for alcohol-approach relative to alcohol-avoid for HS participants (M_D  ± SE_D  = 0.419 ± 0.188 μV, Z = 2.235, P = 0.025). There was also enhanced P3 amplitude for alcohol-approach relative to alcohol-avoid for LS (M_D  ± SE_D  = 0.825 ± 0.204 μV, Z = 4.045, P < 0.001) but not HS (M_D  ± SE_D  = 0.013 ± 0.194 μV, Z = 0.068, P = 0.946).

CONCLUSIONS

Findings from a human laboratory study appear to support the notion that low sensitivity to alcohol indexes a propensity to attribute bottom-up incentive value to naturally conditioned alcohol cues.

Theta-Burst Stimulation Is Able to Impact Cognitive Processing: A P300 and Neuropsychological Test Study

INTRODUCTION

Theta-burst stimulation (TBS) is a safe non-invasive neurostimulation technique used to improve cognitive and neuropsychiatric impairments. Combined outcome evaluation using event-related potentials (ERPs) and neuropsychological tests may allow a more thorough assessment of TBS treatment efficacy; however, some mixed results have been found, and their use remains scarce. Our main objective was to evaluate whether a session of TBS to the left dorsolateral prefrontal cortex (DLPFC) can impact upon the performance of both neuropsychological and neurophysiological tests.

METHODS

This double-blind sham-controlled study involved 28 healthy adults, between 18 and 30 years. Volunteers were randomly allocated to receive excitatory (intermittent [iTBS]), inhibitory (continuous TBS [cTBS]) or sham stimulation on the left DLPFC. Subjects were evaluated using ERPs (auditory oddball paradigm P300) and neuropsychological tests (Trail making test [TMT] and Stroop test of words and colours [STWC]), using a pre-post stimulation protocol.

RESULTS

Inhibitory stimulation led to significantly delayed P300 peak latencies (p < 0.001), with no consistent change in N2P3 amplitudes. cTBS also significantly influenced the expected group performance in Stroop C and Stroop interference (p = 0.025) compared to the iTBS and sham groups. No significant results were found in TMT tests after TBS.

CONCLUSION

Our results suggest that P300 and specific Stroop colour and words test parameters can be similarly influenced by the same TBS protocol. This emphasizes the importance of mixed evaluation using neuropsychological and neurophysiological resources in research associated with the use of transcranial magnetic stimulation and cognition.

Predicting interactions in handedness research: The role of integrated versus independent dual-processes

Over the past two decades, a new way of looking at handedness has emerged (see Prichard, E., Propper, R. E., & Christman, S. D. (2013). Degree of handedness, but not direction, is a systematic predictor of cognitive performance. Frontiers in Psychology, 4, 1-6), with an emphasis on degree (strong/consistent versus mixed/inconsistent) augmenting the traditional emphasis on direction (left versus right) of handedness. Much of this work has focused on main effects: e.g., inconsistent-handers show higher (or lower) performance than consistent-handers. However, many of these "main effects" are actually nested within higher order interactions: e.g., there are no handedness differences in a baseline/control condition, with handedness differences emerging in an experimental condition. Careful examination, though, of these interactions reveals an intriguing and predictable pattern: for integrated dual processes (e.g., episodic memory encoding versus retrieval), the interactions reflect larger effects in inconsistent-, relative to consistent-, handers. For independent, mutually exclusive dual processes (e.g., approach versus withdrawal), the interactions reflect larger effects in consistent-handers. It is argued that these patterns reflect the relative inability of (i) consistent-handers to integrate dual processes, and (ii) inconsistent-handers to keep independent dual processes separate. We also use this same theory to address higher order interactions involving changes in the experimental context as well as other individual difference factors, and make suggestions for future research.

Stability and flexibility in cognitive control: Interindividual dynamics and task context processing

Adaptive behaviour requires cognitive control for shielding current goals from distractors (stability) but at the same time for switching between alternative goals (flexibility). In this behavioural study, we examine the stability-flexibility balance in left- and right-handers during two types of decision-making, instructed (sensory cued) and voluntary (own choice), by means of distractor inhibition and hand/task switching. The data revealed that both groups showed opposite tendencies for instructed decision-making. Moreover, right-handers resisted distracting information more efficiently whereas left-handers showed superior switching abilities. When participants were involved in voluntary decision-making, no effects of handedness were noted, which suggests that free-choice processing alters the balance between stability and flexibility. These data illustrate that handedness is an index of individual variation during instructed decision-making, biasing the proficiency of cognitive control towards stability and flexibility of information processing. These biases can however be overruled by top-down strategies that dominate during voluntary decision-making. Overall, the research underlines the antagonistic functions of stability and flexibility in decision-making, and offers an approach for examining cognitive control and the role of internal and external factors in balancing the stability-flexibility trade-off.