Academic journal article Memory & Cognition

Working Memory and Executive Function: The Influence of Content and Load on the Control of Attention

Academic journal article Memory & Cognition

Working Memory and Executive Function: The Influence of Content and Load on the Control of Attention

Article excerpt

In a series of three experiments, increasing working memory (WM) load was demonstrated to reduce the executive control of attention, measured via task-switching and inhibitory control paradigms. Uniquely, our paradigms allowed comparison of the ability to exert executive control when the stimulus was either part of the currently rehearsed memory set or an unrelated distractor item. The results demonstrated a content-specific effect-insofar as switching attention away from, or exerting inhibitory control over, items currently held in WM was especially difficult-compounded by increasing WM load. This finding supports the attentional control theory that active maintenance of competing task goals is critical to executive function and WM capacity; however, it also suggests that the increased salience provided to the contents of WM through active rehearsal exerts a content-specific influence on attentional control. These findings are discussed in relation to cue-induced ruminations, where active rehearsal of evocative information (e.g., negative thoughts in depression or drug-related thoughts in addiction) in WM typically results from environmental cuing. The present study has demonstrated that when information currently maintained in WM is reencountered, it is harder to exert executive control over it. The difficulty with suppressing the processing of these stimuli presumably reinforces the maintenance of these items in WM, due to the greater level of attention they are afforded, and may help to explain how the cue-induced craving/rumination cycle is perpetuated.

The ability to keep relevant information in mind is considered a crucial aspect of cognitive function, influencing performance across a range of other areas. Working memory (WM) has been described as the "desktop of the brain" (Logie, 1999), in an attempt to encapsulate the on-line, multitask processing and temporary storage system first outlined by Baddeley and Hitch (1974). Of particular interest here is the proposed role for the central executive, considered to be the most complex but least well-understood component of WM (Baddeley, 1996; Baddeley & Della Sala, 1998). Baddeley argues that the central executive may in fact be a conglomeration of several subcomponents, servicing at least four separate functions. These include the coordination of separate task performances, switching retrieval strategies for tasks (such as in random generation), selectively attending to a particular stimulus while simultaneously inhibiting a separate stimulus, and manipulating information sourced from the temporary stores.

The Interaction Between Central Executive Resources and Working Memory Capacity

The recent revision of Baddeley's WM model highlighted the role of central executive resources in strategic processing of information held in the temporary stores (Baddeley, 2001). Baddeley (1996) suggested that the level of performance on the digit-span task, which was argued to involve relatively little complex processing, would be determined primarily by storage rather than by executive function. However, he also cautioned (Baddeley, 1996, 2001) that maximal verbal memory span depended on both the phonological loop and central executive, with participants recruiting central executive resources as the digit load increased past capacity: "As the digit load increased, the demands made on the central executive will increase" (Baddeley, 1996, p. 11). One may infer from this research that maintaining high WM loads requires input from strategic executive processes, such as chunking.

Kane, Engle, and colleagues (Engle, Tuholski, Laughlin, & Conway, 1999; Kane, Bleckley, Conway, & Engle, 2001; Kane & Engle, 2003) have proposed that cognitive measures of WM capacity reflect an individual's capacity to maintain information, including task goals, in a highly active state despite interference. They suggest that keeping relevant information highly active and easily accessible reflects an individual's ability to control attention, because "coherent and goal-oriented behavior in interference-rich conditions requires both the active maintenance of relevant information and the blocking or inhibiting of irrelevant information" (Kane et al. …

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