"Working memory is a fundamental aspect of executive cognition that is thought to encompass three primary mental processes: 1) the access of information, 2) “on-line” operation(s) on this information, and 3) the production of a motor output response based on these operations (Goldman-Rakic, 1987). At present, several distinct theoretical conceptualizations of working memory exist within the cognitive science literature (reviewed in Kimberg, D’Esposito, & Farah, 1998). This lack of consensus may be due, in part, to the functional complexity of working memory, which includes aspects of rehearsal, maintenance, short term storage, attention, and executive control (Kimberg, et al., 1998). Working memory is widely accepted as being dependent on the lateral frontal cortex (Fuster, 1997; Goldman-Rakic, 1987; Owen, et al., 1998; 1999; Owen, 2000), and plays an important role in the temporal coordination of guided behavior via the perception-action cycle (Fuster, 2000). Immediate serial recall and memory span tasks are two common tools used to assess working memory in humans (Baddeley, 1996). In such tasks, the participant is presented with a series of stimuli, and required to recall this stimulus string in sequential order (Baddeley, 1996). In these tasks, the likelihood of correct recall is directly related to the length of the stimulus string, and by manipulating the length of this string, the participant’s working memory capacity (memory span) can be assessed (Baddeley, 1996)."