The episodic buffer in children with intellectual disabilities: An exploratory study

Lucy A Henry

doi:10.1016/j.ridd.2010.04.025

Abstract

Performance on three verbal measures (story recall, paired associated learning, category fluency) designed to assess the integration of long-term semantic and linguistic knowledge, phonological working memory and executive resources within the proposed ‘episodic buffer’ of working memory (Baddeley, 2007) was assessed in children with intellectual disabilities (ID). It was hypothesised that children with ID would show equivalent performance to typically developing children of the same mental age. This prediction was based on the hypothesis that, despite poorer phonological short-term memory than mental age matched peers, those with ID may benefit from more elaborate long-term memory representations, because of greater life experience. Children with ID were as able as mental age matched peers to remember stories, associate pairs of words together and generate appropriate items in a category fluency task. Performance did not, however, reach chronological age level on any of the tasks. The results suggest children with ID perform at mental age level on verbal ‘episodic buffer’ tasks, which require integration of information from difference sources, supporting a ‘delayed’ rather than ‘different’ view of their development.

Highlights

The episodic buffer of working memory (Baddeley, 2000; Baddeley, 2007) is proposed as a limited capacity storage system responsible for integrating information from several sources to create a unified memory, sometimes referred to as a single ‘episode’
Gathercole, Willis, and Adams (2004) used ‘recall of spoken sentences’ to assess integration of phonological short-term memory representations with relevant long-term language knowledge. They argued that this measure tapped a distinct component of working memory in 4–6-year-old children, which was separable from the phonological loop and the central executive; the three components were somewhat related
It is proposed that greater long-term knowledge might compensate children with intellectual disabilities (ID) for their weaker phonological short-term memory on tasks which require the integration of information from both of these sources in the proposed episodic buffer of working memory

Summary

Introduction

The episodic buffer of working memory (Baddeley, 2000; Baddeley, 2007) is proposed as a limited capacity storage system responsible for integrating information from several sources to create a unified memory, sometimes referred to as a single ‘episode’. The current paper is concerned with the integration/binding of linguistic and semantic long-term knowledge with information from the ‘‘slave’’ verbal storage system, the phonological loop, during verbal episodic remembering and thinking tasks It provides an exploratory investigation of whether the functioning of the episodic buffer in children with intellectual disabilities (IQ below 70, associated adaptive and daily living difficulties) is at a level commensurate with their mental age. Alloway, Gathercole, Willis, and Adams (2004) used ‘recall of spoken sentences’ to assess integration of phonological short-term memory representations with relevant long-term language knowledge They argued that this measure tapped a distinct component of working memory in 4–6-year-old children (i.e. the episodic buffer), which was separable from the phonological loop and the central executive; the three components were somewhat related. There is some corroborating evidence that the knowledge base of individuals with ID is more extensive than that of typically developing mental age matched controls (Lukose, 1987; Numminen, Service, & Ruoppila, 2002)

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