ABSTRACT
Executive function (EF) is an umbrella term traditionally used to represent higherorder abilities involved in goal-oriented behavior (Lezak, 1995). Refinement of this notion has seen the inclusion of novelty, or unfamiliarity, as an essential component in activation of the executive system (Shallice, 1990); however, some researchers continue to argue that most daily activities require at least some minimal employment of executive control (Stuss & Alexander, 2000). Cognitive skills commonly ascribed to this domain are sometimes referred to as ‘cold’ executive abilities and include strategic planning, organization, goal setting, behavior monitoring, problem solving, inhibition, working memory, and cognitive flexibility (Anderson, 1998; Fuster, 2002; Hughes, 1998; Temple, 1997; Weyandt & Willis, 1994). Recently it has been acknowledged that empathy, theory of mind, emotional regulation, and affective decision making are essential components to our organization and execution of purposeful behavior, and have been labeled by some as ‘hot’ executive skills (Happaney, Zelazo, & Stuss, 2004; Kerr & Zelazo, 2004). Despite their theoretical distinction, cold and hot EFs are considered intimately
connected and are almost always utilized in combination for daily functions. Indeed, these combined executive skills are thought to provide humankind with the unique capacity for reflection and guilt, and establish our autonomy from the environment. Without these higher level abilities we would be reduced to reflexive creatures, responding, but not truly interacting with our surroundings in a meaningful and constructive way. Given that EFs are central to our ability to purposely mediate our actions, it is easy to appreciate that their developmental trajectory covers childhood
and potentially the lifespan. From the primitive reflexes of the immature and helpless newborn, to the development of imaginative play and self-autonomy of the young child, on to the planning and organization of a career and family in adulthood, and finally to the decline of one’s self-sufficiency in later life. When executive development follows its projected route we see the creation of unique individuals, but when disrupted, either through biological or environmental insults, havoc is wreaked on cognitive, social, academic, and vocational growth. As one would expect, the timing, extent, and location of this disruption is important in defining the type and severity of the deficits suffered. This chapter attempts to provide a brief outline of current views of EFs and their
development over the lifespan. First, the neural circuitry, involving prefrontal areas, that has been proposed to support these functions will be described followed by a discussion of the notion that the ‘central executive’ represents a fractionated but intimately connected set of higher level skills. The developmental trajectory of these unique abilities is then discussed, highlighting when they first come ‘online’ in childhood and reach mature levels. This includes an emphasis on key structural and cognitive milestones that occur at each developmental phase from infancy to old age, as well as an exploration of parallels in advances in both these areas. Finally, comparison of the deficits that underlie executive dysfunction in children as compared to the elderly is included to highlight the complexity of this system and how changes in different aspects can masquerade as equivalent deficits in performance on formal testing.
