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Verbal working memory (WM) has been assumed to involve 2 different systems of maintenance, a phonological loop and a central attentional system. Though the capacity estimate for letters of each of these systems is about 4, the maximum number of letters that individuals are able to immediately recall, a measure known as simple span, is not about 8 but 6. We tested the hypothesis that, unaware of the dual structure of their verbal WM, individuals underuse it by trying to verbally rehearse too many items. In order to maximize the use of verbal WM, we designed a new procedure called the maxispan procedure. When performing an immediate serial recall task, participants were invited to cumulatively rehearse a limited number of letters, and to keep rehearsing these letters until the end of the presentation of the list in such a way that the following letters can no longer enter the phonological loop and must be stored in the attentional system. As we expected, in 3 successive experiments, the maxispan procedure resulted in a dramatic increase in spans compared with the traditional simple span procedure, with spans approaching 8 when the to-be-rehearsed letters were presented auditorily and the following letters visually. These results indicate that simple spans, which have been used for more than a century in intelligence tests and are assumed to measure the capacity of short-term memory (STM), actually reflect the complex interplay between different structures and cognitive processes. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Attentional refreshing allows the maintenance of information in working memory and has received growing interest in recent years. However, it is still ill-defined and several proposals have been put forward to account for its functioning. Among them, some proposals suggest that refreshing relies on the retrieval of knowledge from semantic long-term memory. To examine such a proposal, the present study examined the impact on refreshing of two effects known to affect the retrieval from semantic long-term memory: word frequency and lexicality. In working memory span tasks, participants had to maintain memoranda varying in either frequency, or lexicality while performing concurrent tasks. By examining recall performance in complex span tasks and response times for the concurrent task in Brown-Peterson tasks, the present study provided evidence that long-term memory effects (a) affected recall without interacting with manipulation of refreshing and (b) did not affect refreshing speed. These findings challenge the idea that refreshing acts through the retrieval of knowledge from semantic long-term memory. Different WM models are discussed to account for these findings.

Multiple theories of working memory are described in the chapters of this book and often these theories are viewed as being mutually incompatible, yet each is associated with a supporting body of empirical evidence. This chapter argues that many of these differences reflect different research questions, different levels of explanation, and differences in how participants perform their assigned tasks in different laboratories, rather than fundamental theoretical adversity. It describes a version of a multiple component working memory in which a range of specialized cognitive functions (or mental tools) act in concert, giving the impression, at a different level of explanation, of a unified cognitive system. The chapter argues that more rapid and more substantial scientific progress on the understanding of the concept of working memory would be achieved through identifying the levels of explanation explored within each theoretical framework, and attempting to integrate theoretical frameworks rather than perpetuating debate with no clear resolution in sight.