Measurement and development of executive function

Deposited with permission of the author. © 2001 Dr. Peter AndersonExecutive function is an umbrella term that encompasses the cognitive skills necessary for purposeful, goal directed activity (Lezak, 1995). In order to operationalise this complex psychological construct, a model of executive function was proposed that incorporates four inter-dependent and inter-related subdomains (attentional control, cognitive flexibility, goal setting, information processing). Intact executive functioning is critical for new learning and adaptive functioning, and therefore understanding the normal development of these processes is of clinical significance. Previous research has shown that executive processes are functional in early childhood, but the developmental trajectory of these skills during middle childhood was not clear. A battery of tests (Tower of London, Contingency Naming Test, Rey Complex Figure) was assembled and standardised to investigate the development of executive subdomains in middle childhood. Scoring systems were devised that enabled a detailed analysis ofperforn1ance. Normative and developmental studies verified that the selected tests were age appropriate and sensitive to developmental changes, while clinical validity studies confirmed that the tests were sensitive to executive deficits. Examination of the developn1ental data demonstrated that the executive subdomains matured at different rates. It was also established that most executive function development occurs within middle childhood, with the exception of the attentional control subdomain that matures substantially in innll1cy and early childhood. For processes within the cognitive flexibility, goal setting, and information processing subdomains, a critical period of development was identified between 7 to 9 years of age. A major transition between developmental stages was observed between 11 to 13 years of age, reflected in performance fluctuations