Cowan’s embedded-processes model

Cowan’s embedded-processes model of working memory (1988, 1999, 2005) has been developing since 1988, although the term “embedded processes” did not appear until 1999. One of the most notable differences between Cowan’s model of working memory and Baddeley’s model is in the level of analysis: Cowan uses more generic terms to explain working memory rather than explicit terms favored by Baddeley. For example, rather than supporting specific slave systems, Cowan’s model uses vaguer terminology such as “activated memory”, which according to him is a more all-embracing term. Activated memory is not limited to phonological or visual-spatial information, but can include representations of tactile sensor)’ information, which is lacking from Baddeley’s model, even with the inclusion of an episodic buffer (Cowan, 2005).

Two key elements play a role in Cowan’s model (1988, 1999,2005).The first is activated memory, or sensory and categorical features from long-term memory that are currently in an activated state.The second element is the focus of attention, which is a portion of the activated memory that is in conscious awareness and of limited capacity. It functions to form new episodic links between items that are activated at the same time and which are subsequently integrated into long-term memory. Like Baddeley, Cowan (2005) suggests that the central executive controls, at least in part, the focus of attention through orienting responses that can either attract attention when information is new or interesting, or counteract the central executive when information is not novel. Recently Cowan (2005) has asserted that working memory is “a set of processes that hold a limited amount of information in a readily accessible state for use in an active task” (p. 39). However, there are clear conceptual similarities between the rival theories and Cowan has stated that: “Practically, there may be only subtle (though potentially important) differences between a distinct-buffers view and a more integrated approach” (2005, p. 43).

Ericsson and Kintsch’s long-term working memory theory

Another rival to the multicomponent view is Ericsson and Kintsch’s (1995) theory of long-term working memory (LT-WM). Unlike the models just discussed, LT-WM is meant to describe a specific instance of working memory capacity. Specifically, LT- WM theory accounts for the extensive working memory capacity often displayed by experts and skilled performers as well as the large working memory demands made by text comprehension. Like Cowan’s model, LT-WM theory developed in response to Baddeley’s model, or rather, the inadequacies of Baddeley’s model. In particular, Ericsson and Kintsch (1995) made the case that Baddeley’s model (1986) left unexplained the working memory processes of highly skilled activities (such as piano playing, typing, and reading). It is noteworthy, however, that the LT-WM theory of Ericsson and Kintsch was formulated in 1995, before Baddeley added the episodic buffer as the fourth component of his model in 2000—a component he deemed necessary to help account for “the temporary storage of material in quantities that seemed clearly to exceed the capacity of either the verbal or visual-spatial peripheral subsystems. This shows up particularly clearly in the retention of prose passages” (Baddeley, 2003, p. 202).

In their theory, Ericsson and Kintsch (1995) refer to the temporary storage of information (the traditional view of working memory) as short-term working memory (or ST-WM), which differs from LT-WM in “the durability of the storage it provides and the need for sufficient retrieval cues in attention for access to information in long-term memory” (Ericsson & Kintsch, 1995, p. 211). In highly skilled activities retrieval cues in ST-WM make accessible relevant information in longterm memory. Thus, Ericsson and Kintsch stress the importance of efficient and reliable storage of information, as well as its organization.

 
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