Matching Items (45)
Description
Type 1 Diabetes Mellitus (T1DM) is a chronic disease that requires maintaining tight metabolic control through complex behavioral and pharmaceutical regimens. Subtle cognitive impairments and stress response dysregulation may partially account for problems negotiating life changes and maintaining treatment adherence among emerging adults. The current study examined whether young adults with T1DM physiologically respond to psychological stress in a dysregulated manner compared to non-diabetic peers, and if such individuals also demonstrated greater cognitive declines following psychological stress. Participants included 23 young adults with T1DM and 52 non-diabetic controls yoked to T1DM participants based on age, gender, ethnicity, participant education, and maternal education. Participants completed a laboratory-based social stressor, pre- and post-stressor neurocognitive testing, provided fingerstick blood spots (for glucose levels) and salivary samples (for cortisol levels) at five points across the protocol, and completed psychosocial questionnaires. Related measures ANOVAs were conducted to assess differences between T1DM participants and the average of yoked controls on cortisol and cognitive outcomes. Results demonstrated that differences in cortisol reactivity were dependent on T1DM participants' use of insulin pump therapy (IPT). T1DM participants not using IPT demonstrated elevated cortisol reactivity compared to matched controls. There was no difference in cortisol reactivity between the T1DM participants on IPT and matched controls. On the Stroop task, performance patterns did not differ between participants with T1DM not on IPT and matched controls. The performance of participants with T1DM on IPT slightly improved following the stressor and matched controls slightly worsened. On the Trail Making Test, the performance of participants with T1DM was not different following the stressor whereas participants without T1DM demonstrated a decline following the stressor. Participants with and without T1DM did not differ in patterns of performance on the Rey Verbal Learning Task, Sustained Attention Allocation Task, Controlled Oral Word Association Task, or overall cortisol output across participation. The results of this study are suggestive of an exaggerated cortisol response to psychological stress in T1DM and indicate potential direct and indirect protective influences of IPT.
ContributorsMarreiro, Catherine (Author) / Luecken, Linda (Thesis advisor) / Doane, Leah (Thesis advisor) / Barrera, Manuel (Committee member) / Aiken, Leona (Committee member) / Arizona State University (Publisher)
Created2013
Description
Methods to test hypotheses of mediated effects in the pretest-posttest control group design are understudied in the behavioral sciences (MacKinnon, 2008). Because many studies aim to answer questions about mediating processes in the pretest-posttest control group design, there is a need to determine which model is most appropriate to test hypotheses about mediating processes and what happens to estimates of the mediated effect when model assumptions are violated in this design. The goal of this project was to outline estimator characteristics of four longitudinal mediation models and the cross-sectional mediation model. Models were compared on type 1 error rates, statistical power, accuracy of confidence interval coverage, and bias of parameter estimates. Four traditional longitudinal models and the cross-sectional model were assessed. The four longitudinal models were analysis of covariance (ANCOVA) using pretest scores as a covariate, path analysis, difference scores, and residualized change scores. A Monte Carlo simulation study was conducted to evaluate the different models across a wide range of sample sizes and effect sizes. All models performed well in terms of type 1 error rates and the ANCOVA and path analysis models performed best in terms of bias and empirical power. The difference score, residualized change score, and cross-sectional models all performed well given certain conditions held about the pretest measures. These conditions and future directions are discussed.
ContributorsValente, Matthew John (Author) / MacKinnon, David (Thesis advisor) / West, Stephen (Committee member) / Aiken, Leona (Committee member) / Enders, Craig (Committee member) / Arizona State University (Publisher)
Created2015
Description
Missing data are common in psychology research and can lead to bias and reduced power if not properly handled. Multiple imputation is a state-of-the-art missing data method recommended by methodologists. Multiple imputation methods can generally be divided into two broad categories: joint model (JM) imputation and fully conditional specification (FCS) imputation. JM draws missing values simultaneously for all incomplete variables using a multivariate distribution (e.g., multivariate normal). FCS, on the other hand, imputes variables one at a time, drawing missing values from a series of univariate distributions. In the single-level context, these two approaches have been shown to be equivalent with multivariate normal data. However, less is known about the similarities and differences of these two approaches with multilevel data, and the methodological literature provides no insight into the situations under which the approaches would produce identical results. This document examined five multilevel multiple imputation approaches (three JM methods and two FCS methods) that have been proposed in the literature. An analytic section shows that only two of the methods (one JM method and one FCS method) used imputation models equivalent to a two-level joint population model that contained random intercepts and different associations across levels. The other three methods employed imputation models that differed from the population model primarily in their ability to preserve distinct level-1 and level-2 covariances. I verified the analytic work with computer simulations, and the simulation results also showed that imputation models that failed to preserve level-specific covariances produced biased estimates. The studies also highlighted conditions that exacerbated the amount of bias produced (e.g., bias was greater for conditions with small cluster sizes). The analytic work and simulations lead to a number of practical recommendations for researchers.
ContributorsMistler, Stephen (Author) / Enders, Craig K. (Thesis advisor) / Aiken, Leona (Committee member) / Levy, Roy (Committee member) / West, Stephen G. (Committee member) / Arizona State University (Publisher)
Created2015
Description
The purpose of this study was to examine under which conditions "good" data characteristics can compensate for "poor" characteristics in Latent Class Analysis (LCA), as well as to set forth guidelines regarding the minimum sample size and ideal number and quality of indicators. In particular, we studied to which extent including a larger number of high quality indicators can compensate for a small sample size in LCA. The results suggest that in general, larger sample size, more indicators, higher quality of indicators, and a larger covariate effect correspond to more converged and proper replications, as well as fewer boundary estimates and less parameter bias. Based on the results, it is not recommended to use LCA with sample sizes lower than N = 100, and to use many high quality indicators and at least one strong covariate when using sample sizes less than N = 500.
ContributorsWurpts, Ingrid Carlson (Author) / Geiser, Christian (Thesis advisor) / Aiken, Leona (Thesis advisor) / West, Stephen (Committee member) / Arizona State University (Publisher)
Created2012
Description
Family plays an important yet understudied role in the development of psychopathology during childhood, particularly for children at developmental risk. Indeed, much of the research on families has actually concentrated more on risk processes in individual family members or within-family subsystems. In general, important and complex associations have been found among family-related constructs such as marital conflict, parent-child relationships, parental depression, and parenting stress, which have in turn been found to contribute to the emergence of children's behavioral problems. Research has begun to emerge that certain family system constructs, such as cohesion, organization, and control may influence children's development, but this research has been limited by a focus on parent-reports of family functioning, rather than utilizing observational methods. With notable exceptions, there is almost no observational research examining families of children at developmental risk. This study examined the longitudinal relations among family risk and family system constructs, as well as how family systems constructs mediated the relations between family risk and child outcome. Further, the study examined how developmental risk moderated these relations. The sample followed 242 families of children with and without developmental risk across the transition-to-school period. Family risk factors were assessed at 5 years, using parental reports of symptomatology, parenting stress, and marital adjustment, and observational assessments of the parent-child relationship. Family system constructs (cohesion, warmth, conflict, organization, control) were measured at age 6 using structured observations of the entire family playing a board game. Child behavior problems and social competence were assessed at age 7. Results indicated that families of children with developmental delays did not differ from families of typically developing children on the majority of family system attributes. Cohesion and organization mediated the relations between specific family risk factors and social competence for all families. For families of typically developing children only, higher levels of control were associated with more behavior problems and less social competence. These findings underscore the importance of family-level assessment in understanding the development of psychopathology. Important family effects on children's social competence were found, although the pathways among family risk and family systems attributes are complex.
ContributorsGerstein, Emily Davis (Author) / Crnic, Keith A (Thesis advisor) / Aiken, Leona (Committee member) / Bradley, Robert (Committee member) / Gonzales, Nancy (Committee member) / Arizona State University (Publisher)
Created2012
Description
Described is a study investigating the feasibility and predictive value of the Teacher Feedback Coding System, a novel observational measure of teachers’ feedback provided to students in third grade classrooms. This measure assessed individual feedback events across three domains: feedback type, level of specificity and affect of the teacher. Exploratory and confirmatory factor analysis revealed five factors indicating separate types of feedback: positive and negative academic-informative feedback, positive and negative behavioral-informative feedback, and an overall factor representing supportive feedback. Multilevel models revealed direct relations between teachers’ negative academic-informative feedback and students’ spring math achievement, as well as between teachers’ negative behavioral-informative feedback and students’ behavior patterns. Additionally, a fall math-by-feedback interaction was detected in the case of teachers’ positive academic-informative feedback; students who began the year struggling in math benefitted from more of this type of feedback. Finally, teachers’ feedback was investigated as a potential mediator in a previously established relation between teachers’ self-reported depressive symptoms and the observed quality of the classroom environment. Partial mediation was detected in the case of teachers’ positive academic-informative feedback, such that this type of feedback was accountable for a portion of the variance observed in the relation between teachers’ depressive symptoms and the quality of the classroom environment.
ContributorsMcLean, Leigh Ellen (Author) / Connor, Carol M. (Thesis advisor) / Lemery, Kathryn (Committee member) / Doane, Leah (Committee member) / Grimm, Kevin (Committee member) / Arizona State University (Publisher)
Created2015
Description
Individuals differ in the extent to which they feel connected to their future selves, which predicts time preference (i.e., preference for immediate versus delayed utility), financial decision-making, delinquency, and academic performance. Future self-connectedness may also predict how individuals compare themselves with their past selves, future selves, and other people. Greater connectedness may lead to more self-affirming types of temporal self-comparison, less self-deflating types of temporal self-comparison, and less social comparison. Two studies examined the relation between future self-connectedness and comparison processes, as well as effects on emotion, psychological adjustment, and motivation. In the first study, as expected, future self-connectedness positively predicted self-affirming temporal self-comparison and negatively predicted self-deflating temporal self-comparison and social comparison. In addition, future self-connectedness had beneficial direct and indirect effects on adjustment, emotion regulation, and motivation. Unlike previous research, this study examined all three components of future self-connectedness, as opposed to only one. Exploratory analyses examined the items comprising the similarity-connectedness component and found that the relation of these items to the other variables in the model did not differ, though some of the relations in the model were moderated by college generation status. The second study tested whether increasing future self-connectedness would have similar effects on comparison, adjustment, emotion, and motivation. It implemented a pilot future self-connectedness manipulation, an established identity-stability manipulation, and a control condition. The pilot manipulation and identity-stability manipulation failed to affect future self-connectedness relative to control, and did not affect comparison, motivation, adjustment, or emotion. Future research should ascertain whether there is a causal link between connectedness and social comparison or temporal self-comparison processes. Overall, this research links future self-connectedness to social comparison and temporal self-comparison processes, as well as well-being, emotion, and motivation, which demonstrates the importance of connectedness in new, important areas.
ContributorsAdelman, Robert Mark (Author) / Kwan, Virginia S. Y. (Thesis advisor) / Grimm, Kevin (Committee member) / Aktipis, Athena (Committee member) / Neuberg, Steven (Committee member) / Arizona State University (Publisher)
Created2018
Description
Anxiety disorder diagnosis is a risk factor for alcohol use disorders (AUDs), but mechanisms of risk are not well understood. Studies show that anxious individuals receive greater negative reinforcement from alcohol when consumed prior to a stressor, but few studies have examined whether anxious individuals receive greater negative (or positive) reinforcement from alcohol in a general drinking context (i.e., no imminent stressor). Previous studies have also failed to examine possible moderating effects of specific drinking contexts (e.g., drinking in a group or alone). Finally, no studies have investigated mediating variables that might explain the relationship between anxiety and reinforcement from alcohol, such as physiological response to alcohol (e.g., cortisol response). Data for this study were drawn from a large alcohol administration study (N = 447) wherein participants were randomized to receive alcohol (target peak BAC: .08 g%) or placebo in one of four contexts: group simulated bar, solitary simulated bar, group sterile laboratory, solitary sterile laboratory. It was hypothesized that anxiety would be associated with positive subjective response (SR) under alcohol (above and beyond placebo), indicating stronger reinforcement from alcohol. It was also hypothesized that social and physical drinking context would moderate this relationship. Finally, it was hypothesized that anxiety would be associated with a blunted cortisol response to alcohol (compared to placebo) and this blunted cortisol response would be associated with stronger positive SR and weaker negative SR. Results showed that anxiety was not associated with positive SR in the full sample, but drinking context did moderate the anxiety/SR relationship in most cases (e.g., anxiety was significantly associated with positive SR (stimulation) under placebo in solitary contexts only). There was no evidence that cortisol response to alcohol mediated the relationship between anxiety and SR. This study provides evidence that anxious drinkers expect stronger positive reinforcement from alcohol in solitary contexts, which has implications for intervention (e.g., modification of existing interventions like expectancy challenge). Null findings regarding cortisol response suggest alcohol’s effect on cortisol response to stress (rather than cortisol response to alcohol consumption) may be more relevant for SR and drinking behavior among anxious individuals.
ContributorsMenary, Kyle Robert (Author) / Corbin, William (Thesis advisor) / Chassin, Laurie (Committee member) / Meier, Madeline (Committee member) / Grimm, Kevin (Committee member) / Arizona State University (Publisher)
Created2018
Description
Priced Managed Lanes (MLs) have been increasingly advocated as one of the effective ways to mitigating congestion in recent years. This study explores a new and innovative pricing strategy for MLs called Travel Time Refund (TTR). The proposed TTR provides an additional option to paying drivers that insures their travel time by issuing a refund to the toll cost if they do not reach their destination within specified travel times due to accidents or other unforeseen circumstances. Perceived benefits of TTR include raised public acceptance towards priced MLs, utilization increase of HOV/HOT lanes, overall congestion mitigation, and additional funding for relevant transportation agencies. To gauge travelers’ interests of TTR and to analyse its possible impacts, a stated preference (SP) survey was performed. An exploratory and statistical analysis of the survey responses revealed negative interest towards HOT and TTR option in accordance with common wisdom and previous studies. However, it is found that travelers are less negative about TTR than HOT alone; supporting the idea, that TTR could make HOT facilities more appealing. The impact of travel time reliability and latent variables representing psychological constructs on travelers’ choices in response to this new pricing strategy was also analysed. The results indicate that along with travel time and reliability, the decision maker’s attitudes and the level of comprehension of the concept of HOT and TTR play a significant role in their choice making. While the refund option may be theoretically and analytically feasible, the practical implementation issues cannot be ignored. This study also provides a discussion of the potential implementation considerations that include information provision to connected and non-connected vehicles, distinction between toll-only and refund customers, measurement of actual travel time, refund calculation and processing and safety and human factors issues. As the market availability of Connected and Automated Vehicles (CAVs) is prognosticated by 2020, the potential impact of such technologies on effective demand management, especially on MLs is worth investigating. Simulation analysis was performed to evaluate the system performance of a hypothetical road network at varying market penetration of CAVs. The results indicate that Connected Vehicles (CVs) could potentially encourage and enhance the use of MLs.
ContributorsVadlamani, Sravani (Author) / Lou, Yingyan (Thesis advisor) / Pendyala, Ram (Committee member) / Zhou, Xuesong (Committee member) / Grimm, Kevin (Committee member) / Arizona State University (Publisher)
Created2018
Description
Prior research has established associations between sleep duration and body mass index (BMI) scores and risk for obesity in middle childhood, but it is less clear whether other objectively- and subjectively-measured sleep indicators may be associated with BMI scores, weight status (e.g., obesity), and other estimates of weight and body fat such as waist circumference (WC) and percent body fat. Empirical studies have also demonstrated independent associations between broad self-regulation and sleep indicators and BMI scores, but no study to date has tested these factors in a model together and the extent to which associations between normative sleep problems, weight indicators, and effortful control (EC) may be explained by shared genetic or environmental influences. Data from a large longitudinal study of twins was used to test phenotypic associations between sleep problems at eight years and weight indicators at nine years, including whether EC at eight years moderates these associations. Additionally, multiple quantitative behavior genetic models were used to estimate unique and shared genetic and environmental covariances among normative sleep problems, weight indicators, and EC at eight years of age and whether additive genetic influence on weight in middle childhood differs by child weight status group. Phenotypic findings showed that greater sleep duration at eight years predicted greater decreases BMI at nine years of age for children with low levels of EC at eight years. Greater sleep midpoint variability at eight years predicted greater increases in percent body fat from eight to nine years of age for children with low EC at eight years. Behavior genetic findings showed greater environmental influences on parent-reported sleep duration and quality, as well as objective sleep midpoint variability. Similarly, associations between parent-reported sleep duration and sleep midpoint variability and other sleep indicators and EC were primarily accounted for by shared environmental factors. In contrast, there was high additive genetic influence on objective sleep quantity and quality, all weight indicators, and EC. Many of the associations between sleep indicators, sleep and weight indicators, and among weight indicators were entirely accounted for by shared additive genetic factors, suggesting that common, underlying sets of genes explain these relations.
ContributorsBreitenstein, Reagan Styles (Author) / Doane, Leah D. (Thesis advisor) / Lemery-Chalfant, Kathryn (Committee member) / Perez La Mar, Marisol (Committee member) / Grimm, Kevin (Committee member) / Arizona State University (Publisher)
Created2019