The rate at which individuals need to process information in the 21st Century’s high speed, information packed, constantly changing, competitive environment is overwhelming (Long, 2000). Information processing has been extensively investigated in brain research due to its relationship with cognitive processes such as learning, reading and comprehension (Moravcsik & Kintsch, 1993. Memory seems to be crucial for the cognitive processes of learning because it associates incoming information with information previously retained (Cantor, Engle, & Hamilton, 1991). One of the most accepted forms of assessment in brain studies regarding this component of working memory is a digit/letter span test (La Pointe, & Engle, 1990). This test offers insight into memory. It links to attention span, sequential abilities, and organization of information (Sylwester, 1997).
Studies have identified a relationship between poor performance on digit/letter span tests and diminished memory (Long, 2000). Individuals who experience reading and learning difficulties cannot keep information in its correct, sequential order (Eslinger, 2003). No recall is possible because rapid articulation of information reaches a point of decay (Shmidt & Boshuizen, 1993). Unable to learn at a typical pace of instruction, these individuals miss learning skills and concepts (Watson & Willows, 1995). The NACD Sequential Processing Program is a cognitive training tool that is used in directing such individuals to reach their working memory capacity potential (Long, 2000).
Memory plays a significant role in organizing thoughts and ideas, building outlines and hierarchical order plans, and creating schemas for designed exercises (Parasuraman, 1998). In order for a higher-level process to use the output of a lower-level process, that output must remain available for some minimal amount of time (Groeger, 1992). The human brain is the center for thought, emotion, action planning and self-regulation of mind and body and has a remarkable ability for plasticity based on the input processed (Eslinger, 2003). Brain metabolic activation of processing is measured by Positron Emission Tomography (PET) or functional Magnetic Resonance Imaging (fMRI) (Kintsch, Welsch, Schmalhofer, & Zimny, 1990). Glucose utilization reflects task engagement, and greater verbal fluency is an indication of efficient strategies in cognitive operations where little effort is needed (Bontempi, Jaffard, & Destrade, 1996). Higher processing takes place in the area of the prefrontal cortex (Braver et al., 1997). This area shows activity during object working memory like in planning, focusing attention on an object and switching between tasks (Schoubotz & von Cramon, 2001). However, it is not clear if high intelligence individuals differ from normal/low intelligence individuals in processing as a result of greater glucose utilization (Larson, Haier, Lacasse, & Hazen, 1995).
Neuroimaging studies yield that there is high metabolic activity in different brain areas activated in spatial object memory tasks compared to those in verbal working memory tasks (Eden, Stein, Wood, & Wood, 1995; Pazzaglia & Cornoldi, 1999; Vecchi, Monticellai, & Cornoldi, 1995). NACD Sequential Processing Exercises tax working memory to its capacity in these brain areas by presenting spatial object and verbal tasks. Good cognitive functions depend upon the brain’s abilities to prioritize tasks and switch from parallel processing to sequential processing when the processing load of the tasks is excessive (Humphreys, Tehan, O’Shea, & Bolland, 2000). Simulation experiments which tested the hypothesis that a single learning system is capable of presenting both serial and temporal structures, supported the fact that temporal structure is an integral part of the sequence and where it is altered, the sequence can also change (Dominey, Lelekov, Dominey, & Jeannerod, 1998; Schubotz & von Cramon, 2001). Temporal order is especially vital in everyday life where perceptual abilities and language skills (e.g. typing) must be precisely timed and put in proper order. NACD Sequential Processing Exercises facilitate executive memory, which is a function of temporal order processing (Eslinger, 2003; Weinberger & Gallhofer, 1997). NACD Sequential Processing Training affects the central executive control systems which mediate attention and regulation of processes occurring in working memory (Narayanan, 2003).
Attention and refocusing are a function of the left hemisphere neural network and are especially important when there is interference with the main task or during multitasking (Meyer et al., 1997). In multitasking situations, text comprehension is relatively unaffected by low and intermediate loads on memory and only becomes impaired when the resource demands of one of the tasks are maximal. NACD digit/letter span exercises were developed to increase the ease and speed with which critical elements are retrieved after the interruption (Ericsson, 1988). With digit/letter span training, Ericsson and Linch (2003) reported that individuals managed to remember more than 7 units and that text comprehension is not impaired by long interruptions between reading of consecutive sentences. These findings are important because many daily activities rely on memory interruptions and many concurrent activities demand attention simultaneously.