The Science: Sequential Processing
Information from the environment is stored (memory), then processed (information coded-changes forms) (Anderson, 1995; Roediger & Craik, 1989). Some stages of processing occur at the same time (parallel) in different places of the brain, and some occur one at a time (sequential). Memory systems hold information and processing location. Three major memory systems exist: short-term sensory memory, short-term memory, and long-term memory (Anderson, 1995; Roediger & Craik, 1989). Short-term memory is important in cognitive processing as it serves as the link between sensory information input and information storage in long-term memory (Atkinson & Shiffrin, 1971). Working memory is part of short-term memory and has roots in the mechanism of information processing (Engle, 2000). The speed with which individuals can memorize a list of a given length increases and matches the presentation rates in memory tasks designed to study short-term memory (Kane & Engle, 2000).
Neuroscientists have made great advances in understanding the relationship between cognitive processes and the anatomic organization of the brain. For many years it was believed that memory was a single entity. Today it is known that memory consists of multiple components. Recent research has shown that working memory consists of several subsystems that can be relied on to complete various types of tasks (Eslinger, 2003; Narayanan, 2003). Working memory capacity predicts language comprehension and reasoning performance during early ages of learning and skill acquisition (Kyllonen & Christal, 1990). Utilization of more than one sensory channel, implemented in NACD's sequential processing exercises, leads to a successful and more in depth learning.
Long-term memory depends considerably on working memory (Engle, 2001). The combining of moment-to-moment awareness and instant retrieval of long-term information constitutes working memory, like in mental arithmetic (Rosen & Engle, 1997). Relevant information is stored in long-term memory during task processing, and this information must be potentially accessible during the work on that task. The use of long-term memory as an extension of working memory is possible only under very restricted circumstances. Laboratory studies have shown that a wide range of cognitive exercises, such as problem solving, concept formation and decision-making, can be successfully accounted for by models that permit storage of a very small number of products in short-term memory (Ericsson & Kintch, 2003). Individuals must be able to rapidly store information in long-term memory, which is an ability that requires extensive experience and a large body of relevant knowledge and patterns of the particular type of information involved.
Working memory, based on storage in retrieval from long-term memory, could be attained through practice storage and retrieval speed (Ericsson & Kinch, 2003). Ericsson and Kinch (2003) bring broad research support to emphasize that individual differences in the capacity of working memory is not fundamentally fixed and unchangeable, but rather acquired by the amount of available activation. Ericsson and Kinch (2003) suggest that the capacity of working memory must be far greater than what Miller (1956) claimed in the original study. Expanded working memory capacity occurs by developing methods for storing information in long-term memory in accessible forms (Cantor et al., 1991; Crowder, 1993). Ericsson (1988) found that after 50 hours of digit span practice, participants increased their memory performance. Furthermore, performance was correlated significantly with comprehension task scores (Engle, 2001). NACD intervention is based on specific practices and tasks, therefore making a tremendous change in short-term working memory capacity.
Associative memory sometimes replaces available activation of working memory by providing short-term memory storage of symbolic information (Engle, 2000). The hippocampus controls associative or learned memory, and the frontal cortex is associated with executive functions (Halgren, Boujon, Clarle, Wang, Chauvel, 2002). The primary function of the hippocampus is to consolidate new associations, whereas the prefrontal cortex is necessary for retrieving the products of such associative learning (facts, events, rules) from long-term working memory (Narayanan, 2003). Learned actions are controlled by the cerebral cortex, basal ganglia, and cerebellum (Hikosaka, 2002; Mountcastle, 1998). These brain regions are by no means independent (Hikosaka, 2002).
Most current knowledge about long-term working memory originally comes from studies of high brain processes of exceptional digit recall (Staszewski, 1990). Individuals with high working memory spans are able to keep more of the relevant information active in working memory as they comprehend the sentences (Just & Carpenter, 1992; Moravcsik & Kintsch, 1993). The rule of thumb for mental abacus, for example, is an increase of 1 digit per year with deliberate practice effort (Engle, 2000). This is especially valuable for low span individuals who have difficulty blocking out attention to distracting information in unattended messages. Engle (2001) reported that 65% of subjects with low working memory heard their names mentioned (Cocktail Party Effect) while working on a task, compared to only 20% with high span, meaning that they were easily distracted.
