Event Reasoning as a Function of Working Memory Capacity and Long Term Working Memory Skill

The present research examined the relationship of working memory (WM) capacity and long term working memory (LTWM) skill in complex task performance as a function of expertise. Individual differences in WM capacity and LTWM skills of 62 aviation pilots (Expert = 25, Novice = 37) were related to their performance on a task designed to measure components of flight situation awareness (SA). LTWM skill and WM capacity were not correlated, suggesting they are distinct constructs. Experts have higher LTWM skill compared to novices, and LTWM skill acts as a predictor of Expert SA task performance. The implications of these results are discussed. There is currently a debate in the literature regarding the explanation of individual differences in complex task performance relative to WM capacity (e.g., Baddeley & Hitch, 1974) and LTWM skill (e.g., Ericsson & Kintsch, 1995). The present research addresses this debate. Prior to describing this research, a brief summary of the two theories and the debate is provided. Working memory (WM), defined as a limited, temporary store for processing and storing information (Baddeley & Hitch, 1974), has been studied extensively in various cognitive tasks. Relevant to the present research, individual differences in cognitive task performance are often explained by WM capacity. For example, Just and Carpenter (1992) proposed that WM capacity constrains text comprehension. Once an individual’s WM capacity is reached, the lack of available processing and storage hinders the ability to use and retain new information as well as intermediate products resulting from newly obtained information, resulting in decreased comprehension. Further research suggests a role of WM capacity in performing additional cognitive tasks, such as spatial visualization (Shah & Miyake, 1996), the ability to follow complex directions (Engle, Carullo, & Collins, 1991), and computer problem solving (e.g., Anderson & Jeffries, 1985; Doane, McNamara, Kintsch, Polson, & Clawson; 1992, Doane, Sohn, McNamara, & Adams, 2000; Sohn & Doane, 1997). In this view, WM is thought to reside in short term memory (STM); is believed to have a fixed capacity, although individuals differ in their capacities; and an individual’s WM capacity remains stable over time (e.g., Baddeley & Hitch, 1974). Alternatively, some researchers argue that WM capacity is not fixed (Ericsson & Kintsch, 1995) but instead varies as a function of expertise within a specific domain. This theory is referred to as Long Term Working Memory (Ericsson & Kintsch). LTWM is a theory of a memory process that explains how individuals can extend WM capacity well beyond the proposed seven plus or minus two chunks (Miller, 1956). In LTWM theory, domain-specific knowledge and meaningful experiences are thought to increase individual ability to efficiently encode information into long term memory (LTM) and to create easily accessible retrieval structures. Ericsson and Kintsch (1995) defined a retrieval structure as an organization of meaningful data into a stable structure that can be used to rapidly encode information into and retrieve information from LTM. LTWM uses these retrieval structures as indices to situation-specific information that is temporarily stored in LTM. Because the information is temporarily stored in LTM, after a disruption, a task can still be completed by activating the necessary indices required to retrieve the situation-specific information. The indices change dynamically as a function of the task at hand and the individual’s expertise for that particular task. In summary, the WM capacity and LTWM theories differ in their views about whether WM capacity is fixed for a given individual and how WM capacity responds to the dynamics of task environments. In addition, at first glance they appear to offer competing views of the mechanisms that govern WM capacity and where they reside (STM or LTM). However, some evidence suggests that LTWM and WM coexist, are independent constructs (Sohn & Doane, 2003), and serve distinct roles in cognitive task performance. Sohn and Doane devised a measure of LTWM skill, measured individual WM capacity and LTWM skill, and related these measures to performance on a complex cognitive task. They found that WM capacity and LTWM skill were not correlated, suggesting the two are independent constructs. WM capacity predicted novice task performance, whereas LTWM skill predicted expert task performance. In addition, LTWM skill appeared to have a compensatory role for experts with low WM capacity; experts with high LTWM skill tended to have lower WM capacity. The present study extends Sohn and Doane’s (2003) research paradigm to further examine the roles of WM capacity and LTWM skill in complex cognitive task performance. Specifically, the relationships of WM capacity and LTWM skill are related to aviation pilot performance on a flight situation awareness (SA) task. SA is a term that can be broadly defined as a pilot’s ability to understand his or