L’objectif de ce travail de thèse a été d’avancer dans la compréhension des mécanismes par lesquels les émotions positives modulent cognition et comportement. En nous basant sur des mesures comportementales et électrophysiologiques, nous avons abordé ce questionnement chez des volontaires sains, et des personnes souffrant de schizophrénie, pathologie dans laquelle les affects n’influencent pas le comportement de manière appropriée. Nos résultats montrent que les émotions positives diminuent de manière globale la préparation attentionnelle, un des mécanismes de contrôle cognitif. Néanmoins, lorsqu’elles sont associées à un fort niveau de motivation, elles permettent au contraire une mobilisation plus importante du contrôle cognitif. Cette modulation du contrôle cognitif par les émotions positives est plus susceptible d’apparaitre chez les personnes présentant une tendance marquée à ressentir des émotions négatives. Chez les personnes souffrant de schizophrénie, cette modulation ne s’effectue pas de manière appropriée, y compris lorsque l’expérience affective positive est induite de manière non consciente. / The aim of this project was to deepen our understanding of the mechanisms by which positive emotions modulate cognition and behavior. By using behavioral and electrophysiological measures, we addressed this question in a population of healthy controls, and in patients suffering from schizophrenia, because in this disease affect does not appropriately modulate behavior. Our results show that positive emotions globally decrease attentional preparation, a cognitive control mechanism. Nevertheless, when associated with a high level of motivation, they allow for improved recruitment of cognitive control. This modulation of cognitive control by positive emotions is more likely to appear in individuals who have a marked tendency towards experiencing negative emotions. In patients suffering from schizophrenia, this modulation is not appropriate, not even for non-consciously induced positive affective experiences.

There have recently been considerable advances in our understanding of the neuronal mechanisms underlying multitasking, but the role of multimodal integration for this faculty has remained rather unclear. We examined this issue by comparing different modality combinations in a multitasking (stop-change) paradigm. In-depth neurophysiological analyses of event-related potentials (ERPs) were conducted to complement the obtained behavioral data. Specifically, we applied signal decomposition using second order blind identification (SOBI) to the multi-subject ERP data and source localization. We found that both general multimodal information integration and modality-specific aspects (potentially related to task difficulty) modulate behavioral performance and associated neurophysiological correlates. Simultaneous multimodal input generally increased early attentional processing of visual stimuli (i.e. P1 and N1 amplitudes) as well as measures of cognitive effort and conflict (i.e. central P3 amplitudes). Yet, tactile-visual input caused larger impairments in multitasking than audio-visual input. General aspects of multimodal information integration modulated the activity in the premotor cortex (BA 6) as well as different visual association areas concerned with the integration of visual information with input from other modalities (BA 19, BA 21, BA 37). On top of this, differences in the specific combination of modalities also affected performance and measures of conflict/effort originating in prefrontal regions (BA 6).

Background. Attention deficit hyperactivity disorder (ADHD) patients have been reported to display deficits in action control processes. While it is known that subliminally and consciously induced conflicts interact and conjointly modulate action control in healthy subjects, this has never been investigated for ADHD. Method. We investigated the (potential) interaction of subliminally and consciously triggered response conflicts in children with ADHD and matched healthy controls using neuropsychological methods (event-related potentials; ERPs) to identify the involved cognitive sub-processes. Results. Unlike healthy controls, ADHD patients showed no interaction of subliminally and consciously triggered response conflicts. Instead, they only showed additive effects as their behavioural performance (accuracy) was equally impaired by each conflict and they showed no signs of task-goal shielding even in cases of low conflict load. Of note, this difference between ADHD and controls was not rooted in early bottom-up attentional stimulus processing as reflected by the P1 and N1 ERPs. Instead, ADHD showed either no or reversed modulations of conflict-related processes and response selection as reflected by the N2 and P3 ERPs. Conclusion. There are fundamental differences in the architecture of cognitive control which might be of use for future diagnostic procedures. Unlike healthy controls, ADHD patients do not seem to be endowed with a threshold which allows them to maintain high behavioural performance in the face of low conflict load. ADHD patients seem to lack sufficient top-down attentional resources to maintain correct response selection in the face of conflicts by shielding the response selection process from response tendencies evoked by any kind of distractor.

abstract: Social categories such as race and gender are associated by people with certain characteristics (e.g. males are angry), which unconsciously affects how people evaluate and react to a person of specific social categories. This phenomenon, referred to as implicit bias, has been the interest of many social psychologists. However, the implicit bias research has been focusing on only one social category at a time, despite humans being entities of multiple social categories. The research also neglects the behavioral contexts in which implicit biases are triggered and rely on a broad definition for the locus of the bias regulation mechanism. These limitations raise questions on whether the current bias reduction strategies are effective. The current dissertation sought to address these limitations by introducing an ecologically valid and multidimensional method. In Chapters 1 and 2, the mouse-tracking task was integrated into the implicit association task to examine how implicit biases were moderated in different behavioral contexts. The results demonstrated that the manifestation of implicit biases depended on the behavioral context as well as the distinctive identity created by the combinations of different social categories. Chapter 3 laid groundwork for testing working memory as the processing capacity for the bias regulation mechanism. The result suggested that the hand-motion tracking indices of working memory load could be used to infer the capacity of an individual to suppress the influence of implicit bias. In Chapter 4, the mouse-tracking paradigm was integrated into the Stroop task with implicit associations serving as the Stroop targets. The implicit associations produced various effects including the conflict adaptation effect, like the Stroop targets, which suggested that implicit associations and Stroop stimuli are handled by overlapping cognitive mechanisms. Throughout these efforts, the current dissertation, first, demonstrated that a more ecologically valid and multidimensional approach is required to understand biased behaviors in detail. Furthermore, the current dissertation suggested the cognitive control mechanism as a finer definition for the locus of the bias regulation mechanism, which could be leveraged to offer solutions that are more adaptive and effective in the environment where collaboration and harmony are more important than ever. / Dissertation/Thesis / Doctoral Dissertation Human Systems Engineering 2019

Background: Methamphetamine (MA) abuse is a global crisis that exacerbates sociopolitico-economic burdens in South Africa. MA use is associated with a myriad of neural abnormalities of structure and function, with associated neurocognitive deficits, particularly executive function (EF). Working memory (WM) training has been identified as a potential adjunct to treatment of substance use disorder (SUD) to improve EF in the hope of reducing relapse rates. Neuroimaging suggests MA alters intrinsic resting state functional connectivity (rsFC), and this may contribute to neuropsychological deficits observed in methamphetamine use disorder (MUD). Methods: This nested study analysed data described in Brooks et al. (2016), in which WM training was used as an adjunct to inpatient treatment of MUD. Healthy controls (HC, N = 25) were compared to two MUD groups, one receiving treatment as usual (TAU, N = 17), and one receiving additional cognitive training (CT, N = 24) in the form of a modified version of the ‘N-back' task (C-Ya). This task was also used to assess WMA in the neural scanner, using conditions of 0-back and 1-back across groups. The current research explored these data in a novel manner through examining rsFC. Hypotheses: It was predicted that: 1) HC and MUD participants would differ on measures of WMA, but WMA would improve in MA groups at follow-up compared to baseline and this would be augmented in the CT group; 2) rsFC networks of neural regions supporting WM would be predictive of ability to perform well and improve on WM tasks; and 3) MA groups would display heightened rsFC activity within and between resting state neural networks of the default mode network (DMN) and canonical cognitive control networks (CCNs). Results: Significant differences were observed between HC and MA groups in race and level of education, but not on WMA as tested in the scanner. The CT group, who completed WMA 3-back conditions, demonstrated significant improvement on this task post- intervention. Exploratory regression models showed the WM rsFC network did not demonstrate significant relationships with any clinical, demographic, or WM variables when controlling for multiple comparisons. Heightened connectivity within and between the DMN and CCNs was observed in the MUD compared to the HC group, which provided support for hypothesis 3. Exploratory multivariate regression models demonstrated race, age, education, duration of drug use, and an interaction of group and abstinence may impact rsFC in these networks. Post-hoc analyses identified pairwise network combinations affected by these variables. Conclusions: Despite limitations of this small study, it offers tentative preliminary insights into the largely unexplored field of rsFC in MA populations. This study supports limited research demonstrating hyperconnectivity within and between CCNs and DMN of MA users. This study also offers support for recent research suggesting that easier conditions of the Nback task may not reliably test all aspects of WM function. Exploratory analyses of covariates potentially affecting rsFC provide a platform for directions of future research.

Humans have a tendency to impute structure spontaneously even in simple learning tasks, however the way they approach structure learning can vary drastically. The present study sought to determine why individuals learn structure differently. One hypothesized explanation for differences in structure learning is individual differences in cognitive control. Cognitive control allows individuals to maintain representations of a task and may interact with reinforcement learning systems. It was expected that individual differences in propensity to apply cognitive control, which shares component processes with hierarchical reinforcement learning, may explain how individuals learn structure differently in a simple structure learning task. Results showed that proactive control and model-based control explained differences in the rate at which individuals applied structure learning.

It is a widely held view that humans have control over their food choices and consumption. However, research also suggests that eating behavior is often triggered by contextual cues and guided by automaticities and habits. Interestingly, the dichotomy between automatic and controlled processing has recently been challenged, suggesting that they may be intertwined. In a large female sample (n = 567), we investigated the hypothesis that task-based and self-reported measures of automatic and controlled processing would interact and impact self-reported eating behavior. Results analyzed via structural equation modeling suggest that automatic, but not controlled processing, during a modified flanker task, including a context-specific proportion congruent (CSPC) manipulation, was inversely associated with self-reported self-control. The influence of self-control on unhealthy eating behavior (i.e., uncontrolled and emotional eating, heightened consumption of fat and sugar) was only indirect via habitual behavior, which itself had a strong direct impact. Unhealthy eating was further associated with real-life outcomes (e.g., body mass index (BMI)). Our findings suggest that eating behavior may indeed be guided primarily by automaticities and habits, whereas self-control might facilitate this association. Having self-control over eating might therefore be most effective by avoiding contextual cues eliciting undesired automatic behavior and establishing habits that serve long-term goals.

Evolutionary models of adolescent and young adult risk-taking posit that risk-taking increases during this period of the life span as a strategic way for males, in particular, to show dominance, increase perceptions of attractiveness by the opposite-sex, and maximize their chances of acquiring a romantic partner (and ultimately produce offspring). Consistent with this perspective, existing research demonstrates that attractive females increase risk-taking in single males, in part by enhancing males’ sensitivity to rewards and diminishing their ability to inhibit impulsive behavior. By contrast, romantically committed males engage in less risk taking than their single counterparts, although the mechanisms underlying the effect of romantic partners/partnerships on male risk-taking are less clear. In the present study, I employed a behavioral paradigm that has been used in prior studies of peer influence to examine how romantic partners affect decision-making processes and risk-taking behavior in young heterosexual males (18 to 24 years old). I also explored whether there are particular individual and relationship characteristics that moderate the effect of romantic partners on males’ decision-making. This study was conducted using a sample of 134 romantically involved males (mean age=20.2, SD=1.65; 64% White) who were randomly assigned to participate in one of three experimental conditions: alone, in the presence of an attractive female confederate, or in the presence of their romantic partner. Across conditions, I compared males’ behavioral performance on five outcome measures: risk taking (using the Stoplight Task), preference for immediate rewards (using a Delay Discounting Task), reward learning and cost avoidance (using a modified version of the Iowa Gambling Task), and inhibitory control over both neutral and emotionally charged stimuli (using cognitive and emotional versions of the Stroop Task). I found that the presence of romantic partners diminishes risk taking in males, but that romantic partners do not have a significant impact on males’ sensitivity to rewards (neither immediate nor long-term), sensitivity to loss (i.e., cost avoidance), or their ability to inhibit attention to interfering—neutral or emotional—stimuli. However, improvements in cognitive control in the presence of romantic partners were observed among males who report low levels of passionate love. That is, mildly infatuated males exhibited better cognitive control in the presence of their romantic partners relative to mildly infatuated males who were alone. Partner presence had no such effects among males who reported being highly infatuated with their girlfriends. The presence of an attractive female stranger triggered a protective response among romantically involved males—prompting them to take fewer risks (when they are highly committed to their partners), to more quickly avoid decisions that lead to long-term loss (among older males only), and to exhibit better cognitive control (only among males in relatively longer relationships). The presence of an attractive female stranger did not affect males’ sensitivity to rewards. Evidently, the relative impact of an attractive female stranger on males’ risk taking and decision-making is highly dependent on individual and relationship factors, a finding that emphasizes the importance of context when it comes to understanding males’ relative susceptibility to temptation (e.g., other females) and opportunities for potential risk (e.g., infidelity). By contrast, the dampening effect of romantic partners on male risk taking is neither dependent on individual or relationship characteristics nor the result of romantic partners’ influence on reward sensitivity or inhibitory control. However, given the finding that romantic partners enhance cognitive control when feelings of passionate love are relatively low, future research should examine how passionate love and cognitive control interact to predict risk taking. Although I could not identify potential mechanisms to explain why the presence of romantic partners diminishes males’ risk-taking, the current study demonstrates that under specific circumstances—such as when there is high relationship commitment or when the relationship is relatively long—the presence of an attractive female stranger can stimulate romantically involved males to engage regulatory processes that may contribute to their reduced inclination toward risky behavior in that context. This finding is consistent with prior studies and suggests that the presence of tempting stimuli and potential threats to relationship fidelity can trigger males’ deliberate engagement of regulatory processes in effort to maintain their current romantic relationship. In contrast, males’ reduced inclination to engage in risky behavior in the presence of their romantic partners may be automatically activated (without inducing a particular psychological state) regardless of individual and relationship characteristics. / Psychology

Sensorimotor integration processes play a central role in daily life and require that different sources of sensory information become integrated: i.e. the information related to the object being under control of the agent (i.e. indicator) and the information about the goal of acting. Yet, how this is accomplished on a neurophysiological level is contentious. We focus on the role of theta- and beta-band activities and examine which neuroanatomical structures are involved. Healthy participants (n = 41) performed 3 consecutive pursuit-tracking EEG experiments in which the source of visual information available for tracking was varied (i.e. that of the indicator and the goal of acting). The initial specification of indicator dynamics is determined through beta-band activity in parietal cortices. When information about the goal was not accessible, but operating the indicator was required nevertheless, this incurred increased theta-band activity in the superior frontal cortex, signaling a higher need for control. Later, theta- and beta-band activities encode distinct information within the ventral processing stream: Theta-band activity is affected by the indicator information, while beta-band activity is affected by the information about the action goal. Complex sensorimotor integration is realized through a cascade of theta- and beta-band activities in a ventral-stream-parieto-frontal network.

It seems natural that motor responses unfold smoothly and that we are able to easily concatenate different components of movements to achieve goal-directed actions. Theoretical frameworks suggest that different motor features have to be bound to each other to achieve a coherent action. Yet, the nature of the “glue” (i.e., bindings) between elements constituting a motor sequence and enabling a smooth unfolding of motor acts is not well understood. We examined in how far motor feature bindings are affected by reward magnitude or the effects of an unsigned surprise signal. We show that the consistency of action file binding strength is modulated by unsigned surprise, but not by reward magnitude. On a conceptual and theoretical level, the results provide links between frameworks, which have until now not been brought into connection. In particular, theoretical accounts stating that only the unexpectedness (surprisingness) is essential for action control are connected to meta-control accounts of human action control.