Functional neuroimaging data suggests the existence of three distinct attentional roles, with anatomically distinct neural networks. These are alerting, orienting and conflict resolution (Posner & Peterson, 2003). The third of these, conflict resolution, has also been referred to as executive function (Posner & Fan, 2004; Rueda, Posner & Rothbart, 2004). It is equivalent to Baddeley's (1986) top-down central executive system, which he posited oversaw the operation of various subordinate attentional systems, and has been suggested to encompass working memory, planning, switching and inhibitory control (Ruff & Rothbart, 1996). Indeed, some previous models have suggested it is equivalent to the notion of working memory (Baddeley, 1986). It thus appears that executive function and working memory may refer to the same cognitive ability or construct.
Recently, researchers have begun to elucidate these internal attentional processes, largely through using conflict (e.g. Stroop) tasks which require input from an inhibition system. A seminal study by Garavan (1998) examined mental counting ability, and demonstrated that there is a chronometric cost involved in switching attention from one internal counter to another. Garavan termed this cost, the reaction-time difference between "switch" and "non-switch" trials, a switching effect. He inferred from this that working memory - the internal focus of attention - is limited in capacity.
Gehring and colleagues (2003) demonstrated that various top-down (e.g. subjective expectation and trial-position effects) and bottom-up (e.g. priming and inhibition) influences may have confounded Garavan's (1998) findings. Nonetheless, their data supported the notion of switching effects, which they ascribed to the top-down attentional process of shifting attention from one mental object to another - a process they referred to as set-shifting. Such findings are consistent with the abovementioned "spotlight" model of attention, and support the notion of limited capacity processing. Here, executive function represents mechanisms for regulating conflict amongst thoughts, feelings and responses (Rueda, Posner & Rothbart, 2004). Efficiency in this domain may therefore have significant implications for self-regulation (Ruff & Rothbart, 1996).
Especially important may be effortful control (Rueda, Posner & Rothbart, 2004), which reflects the efficiency of executive function in naturalistic settings. Some researchers have suggested that this is "the individual differences variable most closely related to executive attention" (Ruff & Rothbart, 1996, p.285). Consistent with this, it has been suggested that executive function may underlie self-regulation (Posner et al., 2003). Executive dysfunction, therefore, has significant implications for psychological wellbeing. Indeed, Rueda and colleagues (2004) demonstrated that executive function develops relatively late, and may therefore be susceptible to dysfunction. They observed that it "shows a high vulnerability to deficit, and is therefore involved in many forms of psychopathology" (p.295).