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Scholarly Works (4 results)

  • Thesis
  • Peer Reviewed
UC Irvine Electronic Theses and Dissertations (2018)

Executive control functions (ECF) have captivated the scientific community for their role in predicting academic, professional, and health outcomes. ECF are also susceptible to the effects of stress and dominant theories point to the toxicity of stress, though there are notable inconsistencies. Inconsistencies in the literature might be because research has largely ignored the potential role of individual perceptions: The degree to which a stressor affects ECF may be related to the perception of a stressor as distressing and an individual’s beliefs. Three studies investigated these underlying mechanisms that may account for differences in the effects of stress on ECF.

In Study 1, I investigated the relationship between fictitious performance feedback (either positive or negative) and WM function in young adults while assessing a range of affect and self-belief constructs that might affect WM performance. Multiple regressions demonstrated that positive feedback resulted in better WM performance compared to negative feedback. Furthermore, for participants reactive to feedback, recent

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experiences of stress negatively impacted their performance regardless of feedback type. These findings intimate the relationship between stress and WM but could not address whether this relationship might be explained by perceptions of distress.

In Study 2, I examined chronic stress on later inhibitory control in adolescents from a predominantly low-income background. Linear regression failed to detect a relationship between chronic stress and cognitive function. However, the relationship between chronic stress and perceived distress was statistically significant.

To examine the relationship between chronic stress and perceived distress, the role of individual moderators were included in Study 3. Self-esteem and optimism were found to moderate this relationship: High self-esteem and low optimism attenuated the negative effects of chronic stress on perceived distress, whereas low self-esteem acerbated these effects. Though findings from Study 2 failed to detect a relationship between ECF and chronic stress, the relationship between chronic stress and perceived distress was highlighted, then further explored in Study 3.

Collectively, the data obtained from these three complementary strands of work examine how stress impacts ECF, whether perceived distress accounts for this relationship, and to what extent individual beliefs moderate aspects of this relationship.

    Cover page: Stress and Executive Control: Mediation and Moderation
    • Article
    • Peer Reviewed
    UC Irvine Previously Published Works (2015)
    Working memory (WM), the ability to store and manipulate information for short periods of time, is an important predictor of scholastic aptitude and a critical bottleneck underlying higher-order cognitive processes, including controlled attention and reasoning. Recent interventions targeting WM have suggested plasticity of the WM system by demonstrating improvements in both trained and untrained WM tasks. However, evidence on transfer of improved WM into more general cognitive domains such as fluid intelligence (Gf) has been more equivocal. Therefore, we conducted a meta-analysis focusing on one specific training program, n-back. We searched PubMed and Google Scholar for all n-back training studies with Gf outcome measures, a control group, and healthy participants between 18 and 50 years of age. In total, we included 20 studies in our analyses that met our criteria and found a small but significant positive effect of n-back training on improving Gf. Several factors that moderate this transfer are identified and discussed. We conclude that short-term cognitive training on the order of weeks can result in beneficial effects in important cognitive functions as measured by laboratory tests.
      Cover page: Improving fluid intelligence with training on working memory: a meta-analysis
      • Article
      • Peer Reviewed
      UC Irvine Previously Published Works (2018)
      A growing body of literature demonstrating the malleability of critical higher-order cognitive functions by means of targeted interventions has incited widespread scientific interest, most notably in the form of cognitive training programs. The results are mixed and a point of contention: It has been argued that gains observed in cognitive training are mainly due to placebo effects. To address this, we examined the effect of participant expectations on one type of cognitive training that has been central to the controversy, namely n-back training, by inducing beliefs about expected outcomes. Participants receiving n-back training showed improvements in non-trained n-back performance regardless of expectations, and furthermore, expectations for positive outcomes did not result in any significant gains in an active control group. Thus, there was no detectable expectancy effect in either direction as a function of the cognitive intervention used, suggesting that training-related improvements are unlikely due solely to a placebo effect.
        Cover page: (Un)Great Expectations: The Role of Placebo Effects in Cognitive Training
        • Article
        • Peer Reviewed
        UC Irvine Previously Published Works (2020)
        Early exposure to stressful life events is associated with greater risk of chronic diseases and mental health problems, including anxiety. However, there is significant variation in how individuals respond to environmental adversity, perhaps due to individual differences in processing and regulating emotional information. Differences in cognitive control - processes necessary for implementing goal directed behavior - have been linked to both stress exposure and anxiety, but the directionality of these links is unclear. The present study investigated the longitudinal pathway of environmental stress exposure during early adolescence on later adolescent anxiety, and the possible mediating mechanism of cognitive control. Participants were 674 Mexican-origin adolescents (meanage = 10.8 years, 50% male) enrolled in the California Families Project, an ongoing longitudinal study of Mexican-origin families. In the current analysis, we examined self-reports of environmental stressors at age 14 (Time 1), cognitive control at age 16 (Time 2), and anxiety at age 18 (Time 3). Structural equation modeling revealed that environmental stressors (Time 1) had both direct and indirect effects on later anxiety (Time 3) through their effects on cognitive control (Time 2), even when accounting for prior levels of anxiety (Time 2). Cognitive control accounted for 18% of the association between environmental stressors and adolescent anxiety: an increase in stressors decreased cognitive control (β = -0.20, p < 0.001), however, cognitive control buffers against anxiety (β = -0.10, p = 0.004). These findings deepen our understanding of the mechanisms underlying the development of anxiety and highlight the importance of cognitive control as a potential protective factor.
          Cover page: Predicting Late Adolescent Anxiety From Early Adolescent Environmental Stress Exposure: Cognitive Control as Mediator
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