About the Distinction between Working Memory and Short-Term Memory

Abstract

The theoretical concepts short-term memory (STM) and working memory (WM) have been used to refer to the maintenance and the maintenance plus manipulation of information, respectively. Although they are conceptually different, the use of the terms STM and WM in literature is not always strict. STM and WM are different theoretical concepts that are assumed to reflect different cognitive functions. However, correlational studies have not been able to separate both constructs consistently and there is evidence for a large or even complete overlap. The emerging view from neurobiological studies is partly different, although there are conceptual problems troubling the interpretation of findings. In this regard, there is a crucial role for the tasks that are used to measure STM or WM (simple and complex span tasks, respectively) and for the cognitive load reflected by factors like attention and processing speed that may covary between and within these tasks. These conceptual issues are discussed based on several abstract models for the relation between STM and WM.

Keywords: attention; cognitive load; complex span; short-term memory; simple span; working memory.

Figure 1

Hypothetical models of the relation between STM and WM. There are several ways to hypothesize on the relation between STM and WM. One could consider them as two independent (A) or identical (B) entities. In models (C,D) it is assumed that STM is a part of WM and vice versa. This would imply that there is no transfer of information from WM to STM or from STM to WM. In these models a part of the information in WM is in STM, or a part of the information in STM is in WM. Model (E) would not assume a transfer of information from STM to WM (or vice versa) either. Model (F) proposes that WM is STM plus additional processes. This model fits the models of Baddeley and Cowan in an abstract way. In model (G) it is assumed that information entering STM can be transferred to WM in order to undergo manipulation. After manipulation information is sent back to STM. Model (G) considers WM and STM as two different, but strongly collaborative entities. However, the term WM is not appropriate here, since the actual memorizing takes place in the STM component.