Thesis (Ph.D.)--Ohio University, November, 2009. / Title from PDF t.p. Includes bibliographical references.

Thesis (M.A.)--The University of North Carolina at Greensboro, 2010. / Directed by Susan Calkins; submitted to the Dept. of Psychology. Title from PDF t.p. (viewed Jul. 19, 2010). Includes bibliographical references (p. 49-60).

Dissertation (Ph.D.)--The University of North Carolina at Greensboro, 2009. / Directed by Susan P. Keane; submitted to the Dept. of Psychology. Title from PDF t.p. (viewed May 13, 2010). Includes bibliographical references (p. 80-105).

Thesis (Ph.D.)--University of Delaware, 2006. / Principal faculty advisor: Mary Dozier, Dept. of Psychology. Includes bibliographical references.

Executive functions (EFs) are a set of cognitive operations, including working memory, inhibitory control and attention shifting, that underpin accurate, flexible and coordinated behaviour in many problem-solving contexts. While it seems likely that humans surpass nonhuman animals in EFs, previous research into the evolutionary origins of EFs is limited and lacks systematic comparisons of EFs in human and nonhuman animals. In this thesis, I aimed to overcome these limitations by developing a test battery to study EFs in our closest primate relative, the chimpanzee. Using an individual differences approach, I investigated the performance of 19 chimpanzees on several EF tasks and extracted two factors in an exploratory factor analysis accounting for 70.9 % of the variability. The two measures of working memory loaded onto one factor, suggesting that a common cognitive process underlay performance on both tasks. This factor could be clearly differentiated from a well-established measure of attention shifting, loading onto a second factor. In addition, the measures of inhibitory control did not contribute to a unique factor. Intriguingly, the emerging structure of separable EF processes, paralleled the EF structure suggested for human adults (Miyake et al, 2012). The subsequent comparison of a sub-sample of chimpanzees (n = 12; excluding aged individuals), pre-schoolers (n = 36) and undergraduates (n = 16) on two selected EF tests revealed impressive EF capacities of chimpanzees. Chimpanzees could deal with interference in working memory at levels comparable to four and five year-olds. Additionally, the ability of chimpanzees to shift attention was not significantly different from four year-olds; however, five- year-olds outperformed their primate relatives. My work suggests that important aspects of EFs are shared between humans and chimpanzees; while performance differences in EFs emerge late in human ontogeny. The implications of my results for theories on human cognitive evolution are discussed.

Executive functions (including attentional shifting/flexibility, working memory, and inhibitory control) are strong predictors of children's early school success (Blair & Razza, 2007; Espy et al., 2004). The current study explored questions related to measurement of executive functions in preschool-aged children. Convergent and predictive validity were assessed for two traditional executive function tasks (the Dimensional Change Card Sort and the Day-Night Stroop), a behavioral executive function task (the Head-Toes-Knees- Shoulders, HTKS), and teacher ratings of child classroom behavior (the Child Behavior Rating Scale, CBRS). All measures were low-to-moderately correlated for the full sample of preschoolers. The CBRS and the HTKS tasks were the most consistent predictors of emergent mathematics, vocabulary, and literacy, controlling for child age and Head Start status; however, all tasks were significantly related to each achievement outcome. Additionally, the convergent and predictive validity of the executive function tasks and teacher ratings were examined by Head Start status. Results show that the tasks were more closely related in non Head Start children. For predictive validity, the most notable difference was for the Day-Night Stroop, which was a strong consistent predictor of academic outcomes for non Head Start children but not for Head Start children. Together, these findings provide insight to the convergent and predictive validity of executive function tasks during early childhood and differences in executive function associated with Head Start status. / Graduation date: 2012