Academic journal article Memory & Cognition

Short-Term Retention of a Single Word Relies on Retrieval from Long-Term Memory When Both Rehearsal and Refreshing Are Disrupted

Academic journal article Memory & Cognition

Short-Term Retention of a Single Word Relies on Retrieval from Long-Term Memory When Both Rehearsal and Refreshing Are Disrupted

Article excerpt

Published online: 6 February 2014

# Psychonomic Society, Inc. 2014

Abstract Many working memory (WM) models propose that the focus of attention (or primary memory) has a capacity limit of one to four items, and therefore, that performance on WM tasks involves retrieving some items from long-term (or secondary) memory (LTM). In the present study, we present evidence suggesting that recall of even one item on a WM task can involve retrieving it from LTM. The WM task required participants to make a deep (living/nonliving) or shallow ("e"/no "e") level-of-processing (LOP) judgment on one word and to recall the word after a 10-s delay on each trial. During the delay, participants either rehearsed the word or performed an easy or a hard math task. When the to-be-remembered item could be rehearsed, recall was fast and accurate. When it was followed by a math task, recall was slower, error-prone, and benefited from a deeper LOP at encoding, especially for the hard math condition. The authors suggest that a covert-retrieval mechanism may have refreshed the item during easy math, and that the hard math condition shows that even a single item cannot be reliably held in WM during a sufficiently distracting task-therefore, recalling the item involved retrieving it from LTM. Additionally, performance on a final free recall (LTM) test was better for items recalled following math than following rehearsal, suggesting that initial recall following math involved elaborative retrieval from LTM, whereas rehearsal did not. The authors suggest that the extent to which performance on WM tasks involves retrieval from LTM depends on the amounts of disruption to both rehearsal and covert-retrieval/refreshing maintenance mechanisms.

Keywords Short-term memory · Working memory · Long-term memory

Introduction

Cognitive psychologists and neuroscientists have increasingly acknowledged the close relation between short-term or work- ing memory (WM) and long-term memory (LTM; see Jonides, Lewis, Nee, Lustig, Berman & Moore, 2008,forareview). For example, views on the capacity of WM have systemati- cally shrunk from Miller's(1956) magical number 7± 2, to Cowan's(2001) magical number 4, to others who now place the limit at one item (McElree, 2006). Thus, given that WM tests typically require recalling more than one item, recall on tests ostensibly measuring WM may actually involve LTM processes to a substantial degree.

Store models of WM suggest that a small number of items (e.g., four) may be maintained in a temporary store (Atkinson &Shiffrin,1968; Waugh & Norman, 1965)-for example, domain-specific buffers (Baddeley, 1986) or primary memory (Unsworth & Engle, 2007); accessing further items must involve retrieving them from LTM via the episodic buffer (Baddeley, 2000) or secondary memory (Atkinson & Shiffrin, 1968;Unsworth&Engle,2007;Waugh& Norman, 1965). State models suggest that information "in WM" consists of representations that vary in their level of activation. Cowan (2001) suggested that four chunks of infor- mation may be within the focus of attention; accessing other recently processed information requires retrieval from the activated portion of LTM. McElree (2006) suggested that only one item may be in the focus of attention at any given time and that accessing other items requires retrieval from LTM. Oberauer (2002) also suggested that only one item can be in the focus of attention, but that a small number (e.g., three) of recently processed items may remain in a "region of direct access" or "broad focus" (Oberauer & Hein, 2012); accessing items outside this region involves retrieving them from the activated portion of LTM.1

In sum, the models reviewed above all claim that at least one item can be maintained in WM over short delays. Recently, we presented evidence that patient H.C., an amnesic with LTM impairment due to damage to her hippocampus, could not reliably maintain a single item in WM if rehearsal was disrupted and/or the stimulus was novel (Rose, Olsen, Craik & Rosenbaum, 2012). …

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