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Nonsuicidal self-injury (NSSI), the deliberate self-destruction of one’s own body tissue engaged in without associated suicidal intent, is a prevalent behavior among adolescents and young adults. The current study examined whether one aspect of cognitive control, inhibitory control in response to negative emotional stimuli, is associated with repetitive engagement in NSSI. It further sought to examine whether sleep deficiency/irregularity, stress, and reward sensitivity moderate this relationship. A multi-method approach (self-report, behavioral measures, actigraphy) was employed to sensitively probe these relationships among 114 late adolescents with and without a history of repetitive NSSI. Findings suggested no relationship between inhibitory control in response to negative emotional stimuli and NSSI, as measured by a behavioral measure, but a significant positive relationship as measured by self-report. Stress and sleep irregularity, but not sleep deficiency or reward sensitivity, were associated with NSSI group status. Interaction analyses suggested that sleep irregularity and stress moderated the relationship between inhibitory control in response to negative emotional stimuli and NSSI. Results are discussed in terms of conceptual and clinical implications. Findings highlight the necessity of examining the temporal dynamics between the study’s constructs and NSSI by employing an ecologically valid approach. / Psychology

This thesis investigates predictions from prominent conflict theories of cognitive control that information experienced under high conflict conditions should be better encoded. More specifically, recent research suggests that selectively attending to relevant stimuli while ignoring conflicting stimuli can lead to better memory. These ideas have been broadly discussed in the desirable difficulty literature – described by instances where increasing difficulty during initial task performance leads to better later memory. As a growing number of studies have attempted to produce these effects with mixed success, calls for more focused investigations into the underlying mechanisms have been made. This encoding benefit for high-control-demand or high-difficulty situations has been broadly conceptualized as a task-general property, where all activated representations should be better encoded. The goal of this thesis was to investigate whether memory-enhancing effects of difficulty manipulations depend on inducing additional cognitive control at particular information processing stages. This thesis documents some of the first work showing that the within-task locus of conflict and attentional control is critical to whether later memory benefits are seen – conflict/control focused on semantic item representation produces better memory, but conflict/control focused away from item representations at response selection gives no memory benefit. These findings and theory are then extended to physiological measures of pupil dilation and sequential (Grattron-like) conflict/control situations. This thesis proposes a stage-specific conflict-encoding model which complements and extends current leading theories of conflict-driven cognitive control. / Dissertation / Doctor of Philosophy (PhD) / There is an intuitive notion that making a learning experience hard will hinder memory of that information later on. Contrary to this belief, in certain circumstances, making learning difficult can actually enhance the memory of that information – this has been termed desirable difficulty. The issue with these desirable difficulties is that they are only sometimes effective. Originally it was proposed that general task-wide difficulty would lead to an enhancement in memory. This thesis, however, provides evidence suggesting that task difficulty is stage-specific in nature, meaning that for the difficulty to enhance memory, the difficulty needs to be at a specific stage of cognitive processing. For difficulty to have a beneficial effect on memory, the particular difficulty needs to focus an individual’s attention on the core meaning of what they are trying to remember, or else the difficulty will direct attention away from this important information causing a possible decrease in memory. These findings provide a framework for how and when to use difficulty as a means to enhance learning.

The success of many of our activities depends on how we learn to adapt cognitive control: Usually, we focus and redirect our behavior towards our objectives when facing a particularly challenging task or when irrelevant information activates a response that conflicts with our goals, while we relax and let events guide us when the task is familiar or undemanding. Although most of the theories defining cognitive control tend to describe it as a domain-general construct, several researchers posit that each task elicits different types of control adaptations, thus implying that the control adjustments learned in one task might be purely task-specific. Indeed, some studies failed to find a transfer of control preparation strategies between tasks, while others have even questioned whether individuals can prepare for response conflict overall. To provide clarification, this project aims to (1) understand whether people can learn to employ prior control demands to prepare for subsequent task’s demands and (2) understand whether control adaptation rules (or strategies) devised in one task are indeed task-specific, or they can be transferred to other paradigms. In summary, our results provide evidence of transfer of control adaptation rules between tasks requiring control, and maltransfer of these control strategies towards tasks that do not involve variations in control demands. Moreover, our findings suggest that control adaptations rely on potentially generalizable learning strategies, which can encompass both bottom-up associative learning and a top-down strategic proactive mechanism. Overall, the outcomes of this research project are consistent with a domain-general view of cognitive control adaptations.

Intrusive memories are memories for negative autobiographical events that come to mind without being deliberately recalled (Hackmann, Ehlers, Speckens, & Clark, 2004). Previous research has demonstrated that intrusive memories, and negative reactions to intrusive memories, are an important feature of depression (Starr & Moulds, 2006; Williams & Moulds, 2008b) and contribute to the maintenance of depression longitudinally (Newby & Moulds, 2011c). It has also been established that intrusive memory experience is related to individual differences in cognitive control, specifically in proactive interference resolution (Verwoerd, Wessel, & de Jong, 2009; Verwoerd, Wessel, de Jong, Nieuwenhuis, & Huntjens, 2011). The present thesis aimed to extend upon these existing findings, using the Dual Mechanism of Control theory, which distinguishes between proactive and reactive modes of control (Braver, Gray, & Burgess, 2007). Furthermore, in view of some recent ambiguity of the defining feature of an intrusive memory, as compared to a negative involuntary memory more generally (Kvavilashvili, 2014; Moulds & Krans, 2015), another goal of the thesis was to incorporate a wider focus of involuntary memories, rather than focusing only on traditionally studied intrusive memories. Participants from the student population and local community were tested. Overall, results provide some evidence for a negative involuntary memory related deficit in proactive control, on both a classic and an emotional version of the AX-Continuous Performance Task (AX-CPT). Conversely, there was no link between intrusive or involuntary memory experience and reactive control. A brief mindfulness and self-compassion based intervention, designed to reduce negative reactions to intrusive memories, was also tested. The intervention was successful in reducing intrusive-memory distress, and recommendations for the future development of the intervention are presented.

The current thesis explores the complex relationship between cognitive control and memory. A series of experiments combined task-switching paradigms with recognition memory tests to measure how switching between tasks influences effective control over long-term memory. In these experiments, participants were presented with compound stimuli consisting of a picture and an overlaid word, and were cued in each trial whether the word or the picture was relevant (attended) or irrelevant (unattended). Participants were then tested for their memory of items presented during task switching. Experiments 1-2 indicated that switching between tasks reduces the selectivity of processing: Switching was associated with impaired task performance as well as more similar memory ratings for attended and unattended items. Experiments 3-5 extended these findings by showing that enhanced top-down control positively affected task-performance as well as memory, in both cases by increasing the selectivity of processing toward task-relevant information. Experiments 6-7 replicated key effects with simple switches of visual attention, and explored the neural correlates of successful task performance and encoding using EEG. The key finding here was that previously observed ―subsequent memory‖ effects reflect, at least in part, selective encoding processes. The last chapter extended the focus of the investigation to explore the role of control in long-term memory retrieval. FMRI meta- analyses indicated considerable overlap in neural activation found during task switching and during the adoption of different retrieval sets. The results of Experiment 8 indicated that switching during task performance and later memory retrieval were both associated with decreased selectivity of processing. Collectively, the results of this thesis suggest that selectivity of processing is a critical factor in effective task performance and successful memory, with potentially very similar mechanisms underlying the two. This work demonstrates the fruitfulness of combining research on cognitive control and memory to study questions relevant for both fields.

<p>The research studies presented as this dissertation constitute a methodologically diverse and conceptually integrative approach to understanding impulsiveness in the context of cognitive control and decision making. Broadly, these findings address the validity of current conceptions of trait impulsiveness, relationships between those traits and brain or laboratory measures of cognitive control, and links between impulsive traits and economic decisions under conditions of delay or uncertainty. The findings presented in this thesis affirm the multidimensional nature of impulsiveness as a construct, and link individual differences in specific impulsive types to behavioral and neurobiological measures of control function. The nature of motor, attentional, and nonplanning impulsive types are contextualized by reference to evidence supporting a broad theory of behavioral control based on hierarchical organization of action, ranging from concrete acts to abstract plans and strategies. We provide evidence linking concrete forms of urgent/motor impulsiveness to behavior and brain activation during response-related control, and more abstract and future-oriented premedititative/nonplanning impulsiveness to strategic control signals in more rostral PFC. Finally, these findings are complemented by causal evidence from a neurostimulation study linking a contextual control network to risky decision making and attentional impulsiveness.</p> / Dissertation

Social functioning impairments are a core, debilitating, and treatment refractory feature of schizophrenia. The mechanisms contributing to these impairments are unknown. Cognitive control mechanisms, mediated by the lateral prefrontal cortex (LPFC), are known to influence response to interpersonal stressors in healthy individuals, thus impairments in these processes may contribute to social deficits. Deficits in cognitive control and lateral prefrontal abnormalities are well-documented in schizophrenia, but the relationship between these deficits and social interactions has received limited attention in the literature. The current dissertation presents a systematic examination of the contribution of the behavioral and neural mechanisms of cognitive control to social functioning impairments in schizophrenia. Three papers are presented. / Psychology

<p>Involuntary episodic memories are memories that come into consciousness without preceding retrieval effort. These memories are commonplace and are relevant to multiple mental disorders. However, they are vastly understudied. We use a novel paradigm to elicit involuntary memories in the laboratory so that we can study their neural basis. In session one, an encoding session, sounds are presented with picture pairs or alone. In session two, in the scanner, sounds-picture pairs and unpaired sounds are reencoded. Immediately following, participants are split into two groups: a voluntary and an involuntary group. Both groups perform a sound localization task in which they hear the sounds and indicate the side from which they are coming. The voluntary group additionally tries to remember the pictures that were paired with the sounds. Looking at neural activity, we find a main effect of condition (paired vs. unpaired sounds) showing similar activity in both groups for voluntary and involuntary memories in regions typically associated with retrieval. There is also a main effect of group (voluntary vs. involuntary) in the dorsolateral prefrontal cortex, a region typically associated with cognitive control. Turning to connectivity similarities and differences between groups again, there is a main effect of condition showing paired > unpaired sounds are associated with a recollection network. In addition, three group differences were found: (1) increased connectivity between the pulvinar nucleus of the thalamus and the recollection network for the voluntary group, (2) a higher association between the voluntary group and a network that includes regions typically found in frontoparietal and cingulo-opercular networks, and (3) shorter path length for about half of the nodes in these networks for the voluntary group. Finally, we use the same paradigm to compare involuntary memories in people with posttraumatic stress disorder (PTSD) to trauma-controls. This study also included the addition of emotional pictures. There were two main findings. (1) A similar pattern of activity was found for paired > unpaired sounds for both groups but this activity was delayed in the PTSD group. (2) A similar pattern of activity was found for high > low emotion stimuli but it occurred early in the PTSD group compared to the control group. Our results suggest that involuntary and voluntary memories share the same neural representation but that voluntary memories are associated with additional cognitive control processes. They also suggest that disorders associated with cognitive deficits, like PTSD, can affect the processing of involuntary memories.</p> / Dissertation