Re-Examining the Stop-Signal Task to Test Competing Theories of AD/HD

The current study tested two competing models of Attention-Deficit/Hyperactivity Disorder (AD/HD), the inhibition and state regulation theories, by conducting fine-grained analyses of the Stop-Signal Task and another putative measure of behavioral inhibition, the Gordon Continuous Performance Test (G-CPT), in a large sample of children and adolescents. The inhibition theory posits that performance on these tasks reflects increased difficulties for AD/HD participants to inhibit prepotent responses. The model predicts that putative stop-signal reaction time (SSRT) group differences on the Stop-Signal Task will be primarily related to AD/HD participants requiring more warning than control participants to inhibit to the stop-signal and emphasizes the relative importance of commission errors, particularly "impulsive" type commissions, over other error types on the G-CPT. The state regulation theory, on the other hand, proposes response variability due to difficulties maintaining an optimal state of arousal as the primary deficit in AD/HD. This model predicts that SSRT differences will be more attributable to slower and/or more variable reaction time (RT) in the AD/HD group, as opposed to reflecting inhibitory deficits. State regulation assumptions also emphasize the relative importance of omission errors and "slow processing" type commissions over other error types on the G-CPT. Overall, results of Stop-Signal Task analyses were more supportive of state regulation predictions and showed that greater response variability (i.e., SDRT) in the AD/HD group was not reducible to slow mean reaction time (MRT) and that response variability made a larger contribution to increased SSRT in the AD/HD group than inhibitory processes. Examined further, ex-Gaussian analyses of Stop-Signal Task go-trial RT distributions revealed that increased variability in the AD/HD group was not due solely to a few excessively long RTs in the tail of the AD/HD distribution (i.e., tau), but rather indicated the importance of response variability throughout AD/HD group performance on the Stop-Signal Task, as well as the notable sensitivity of ex-Gaussian analyses to variability in data screening procedures. Results of G-CPT analyses indicated some support for the inhibition model, although error type analyses failed to further differentiate the theories. Finally, inclusion of primary variables of interest in exploratory factor analysis with other neurocognitive predictors of AD/HD indicated response variability as a separable construct and further supported its role in Stop-Signal Task performance. Response variability did not, however, make a unique contribution to the prediction of AD/HD symptoms beyond measures of motor processing speed in multiple deficit regression analyses. Results have implications for the interpretation of the processes reflected in widely-used variables in the AD/HD literature, as well as for the theoretical understanding of AD/HD.

Challenges and Opportunities in Managing the Aging Workforce: An Investigation of the Federal Emergency Management Agency

The aging workforce is becoming the majority of the working population in the United States. Although the literature on the aging workforce is sizable, little exists on how public agencies use the older workers. This capstone project examines the challenges and opportunities related to the employment of older workers as seen through a case study of the Federal Emergency Management Agency (FEMA). Knowledge gained from a synthesis of the literature review with survey data collected and analyzed will enable HR professionals to better understand the demographic, economic, regulatory, and intellectual influences of the aging workforce. The results from the survey of FEMA employees suggest a basis to plan and implement successful hiring and retention policies related to the aging workforce.

Pieter Bruegel the Elder’s Netherlandish Proverbs and Sixteenth Century Dutch Semiotics

"In 1559, Pieter Bruegel the Elder‘s depiction of {7f2015}Netherlandish Proverbs‖ illustrated his profound understanding of the Dutch love for proverbs, their contemporary values, and appreciation for moral lessons in art forms. Depicting gestures and poses that represented proverbial phrases enabled Bruegel‘s leap from didactic labels employed by other artists to his inscription-free success of {7f2015}Netherlandish Proverbs.‖ My examination reveals that Bruegel‘s employment of gestural imagery, indicating rhetorical phrases or proverbs, was reinforced by a history of scholarly curatorship for written proverb collections, humanist interest in proverbs, and use of Dutch vernacular to bolster protonational pride"