Date of Award

Spring 5-15-2006

Document Type


Degree Name

Doctor of Psychology (PsyD)


Graduate Department of Clinical Psychology

First Advisor

Wayne Adams, Ph.D

Second Advisor

Kathleen Gathercoal, Ph.D

Third Advisor

Gale Roid, Ph.D


The purpose of this study is to examine the development of Executive Function (EF). Specifically, this study investigates whether there are consistent increases in EF performance on the Delis-Kaplan Executive Function System (D-KEFS) from the age of 8 years to 15 years. Gender differences in the development of EF are also examined. To this end, the standardization data for eight of the D-KEFS tests were analyzed, comparing performance across age groups (8- year-olds, 9-year-olds, etc.) and gender groups. Significant age effects were found for all tests overall. However, significant change between consecutive age groups was found only for some age groups, on some tests. Gender effects were significant for two D-KEFS tests. However, age and gender interaction effects were not significant for any test. The results suggest that EF is developing, in irregular patterns, between the ages of 8 years and 15 years. There is not evidence for significant gender differences in the developmental course ofEF as measured by the D-KEFS.