Doctor of Philosophy

dissertationThis dissertation begins with an overview of skilled performance and how hierarchical control theory (HCT) has been successful in explaining skilled performance. Next, two novel premises of HCT are generated that provide evidence for distinct, hierarchical control systems (outer and inner loops). These control systems have unique properties and lead to very different predictions when applied to complex skills. By manipulating primary task predictability and secondary task workload of a complex skill, these properties can be dissociated. This is followed by an application of HCT to driving and driver distraction. I discuss how secondary task cognitive workload affects driving performance and how previous research has not explained paradoxical patterns of driving performance (i.e., lane maintenance). Then two premises of HCT are generated and used to make predictions about lane maintenance. Next, another influential theory of skilled performance (ACT-R) is discussed, and this theory is contrasted with HCT in terms of predictions regarding lane maintenance. Two experiments are designed to test HCT and differentiate it from ACT-R. The results support the predictions of HCT and suggest that ACT-R is somewhat limited in its ability to fully explain lane maintenance. HCT provides a framework for future driving research as well as future research on a variety of complex skills

Impact of COVID-19 on cardiovascular testing in the United States versus the rest of the world

Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-US institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic. Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality. Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States. Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p < 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis. Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection

Who multi-tasks and why? Multi-tasking ability, perceived multi-tasking ability, impulsivity, and sensation seeking.

The present study examined the relationship between personality and individual differences in multi-tasking ability. Participants enrolled at the University of Utah completed measures of multi-tasking activity, perceived multi-tasking ability, impulsivity, and sensation seeking. In addition, they performed the Operation Span in order to assess their executive control and actual multi-tasking ability. The findings indicate that the persons who are most capable of multi-tasking effectively are not the persons who are most likely to engage in multiple tasks simultaneously. To the contrary, multi-tasking activity as measured by the Media Multitasking Inventory and self-reported cell phone usage while driving were negatively correlated with actual multi-tasking ability. Multi-tasking was positively correlated with participants' perceived ability to multi-task ability which was found to be significantly inflated. Participants with a strong approach orientation and a weak avoidance orientation--high levels of impulsivity and sensation seeking--reported greater multi-tasking behavior. Finally, the findings suggest that people often engage in multi-tasking because they are less able to block out distractions and focus on a singular task. Participants with less executive control--low scorers on the Operation Span task and persons high in impulsivity--tended to report higher levels of multi-tasking activity

Capacity Coefficient Variations

The capacity coefficient has become an increasingly popular measure of efficiency under changes in workload. It has been used in applications ranging from psychophysical detection tasks to complex cognitive tasks, as well as in addressing questions in social and clinical psychology. The basic formulation compares response times to each stimulus property (or task) in isolation to response times with all stimulus properties (or tasks) at the same time. A number of variations on the basic capacity coefficient have been used, both in the experimental design and in the calculations, and many more are possible. Here we outline the theoretical reasons for the different variations and discuss the information researchers need to choose the appropriate variation of the capacity coefficient. We then compare the different analyses applied to two cognitive tasks: an audio-visual detection task and a dual n-back task

Means and standard deviations (in parentheses) for multi-tasking ability (OSPAN), perceived multi-tasking ability, impulsivity, and sensation seeking for participants in the upper and lower quartiles of multi-tasking activity (MMI).

<p>Also indicated are the degrees of freedom, t-test scores, and the effect size estimate, Cohen’s d.</p>*<p>Significant at .05 level.</p>**<p>Significant at .01 level.</p

Linear regression standardized Beta coefficients and corresponding t-scores for multi-tasking ability (OSPAN), perceived multi-tasking ability, attentional impulsivity, non-planning impulsivity, and disinhibition in predicting multi-tasking activity and cell phone use while driving.

<p>Beta refers to the standardized coefficients.</p>*<p>Significant at .05 level.</p>**<p>Significant at .01 level.</p

Means and standard deviations (in parentheses) for multi-tasking ability (OSPAN), perceived multi-tasking ability, impulsivity, and sensation seeking for participants in the upper and lower quartiles of cell phone use while driving.

<p>Also indicated are the degrees of freedom, t-test scores, and the effect size estimate, Cohen’s d.</p>*<p>Significant at .05 level.</p>**<p>Significant at .01 level.</p

Correlations between multi-tasking activity, multi-tasking ability, perceived multi-tasking ability, impulsivity, and sensation seeking.

<p>N = 277.</p>*<p>Significant at .05 level.</p>**<p>Significant at .01 level.</p