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Front. Psychol. | doi: 10.3389/fpsyg.2018.02581

Verbal Working Memory Processes in Students with Mild and Borderline Intellectual Disabilities: Differential Developmental Trajectories for Rehearsal and Redintegration

 Gunnar Bruns1*, Birgit Ehl1 and  Michael Grosche1
  • 1University of Wuppertal, Germany

In verbal working memory, two processes serve to retain a fading memory trace: subvocal rehearsal and lexical redintegration. While recent studies on students with mild and borderline intellectual disabilities (MBID) have yielded mixed results on rehearsal, redintegration has not been researched in MBID, yet. Furthermore, most studies have used a group-matched design which, due to methodological constraints, can only distinguish between two different development patterns. Thus, we study both rehearsal and redintegration in students with MBID using developmental trajectories that have better potential of identifying differential developmental patterns than traditional group-matching approaches. We investigate whether three aspects in working memory develop differently in students with MBID in comparison to typically developing students: (a) the general capacity of the phonological loop, and the effectiveness of (b) rehearsal, and (c) redintegration. We use three different developmental indicators to compare trajectories: chronological age, cognitive capacity, and vocabulary size. N = 210 students (87 students with MBID, 123 typically developing students) completed working memory span tasks with short and long (1- vs. 3-syllable) real words and pseudowords. The effect for word-length (short vs. long) measures rehearsal, and the lexicality effect (real words vs. pseudowords) measures redintegration. Results show that developmental trajectories reveal an intercept difference but no slowed rate in rehearsal, and no impairment in redintegration. However, concerning the developmental relation between redintegration and vocabulary size, students with MBID reveal a differential pattern as redintegration appears higher for students with small vocabulary size, but unexpectedly decreases with growing vocabulary size. We conclude that students with MBID show a delayed onset in the development of capacity of the phonological loop and rehearsal and that they do not catch up in their development. Redintegration does not seem to be impaired in relation to age and cognitive capacity. However, the differential relation of redintegration with vocabulary size calls for further research. While impaired subvocal rehearsal appears to be connected to developmental problems that students with MBID have, lexical redintegration seems to be intact in relation to chronological age and cognitive capacity posing a possible area of strength.

Keywords: working memory, Mild Intellectual Disability (MID), Borderline intellectual disability, rehearsal, Redintegration, developmental trajectories, Delayed onset, phonological loop

Received: 21 Aug 2018; Accepted: 03 Dec 2018.

Edited by:

Peter Klaver, University of Surrey, United Kingdom

Reviewed by:

Yoshifumi Ikeda, Joetsu University of Education, Japan
Vrinda Kalia, Miami University, United States  

Copyright: © 2018 Bruns, Ehl and Grosche. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Mr. Gunnar Bruns, University of Wuppertal, Wuppertal, Germany, gbruns@uni-wuppertal.de