Working memory in children with mild intellectual disabilities: abilities and training potential

The two main objectives of this thesis are a) to unravel working memory (WM) strengths and weaknesses in children with mild intellectual disabilities (MID), and b) to investigate if WM can be trained effectively in these children. Chapter 1 provides an introduction to the thesis and encompasses information about the concepts used in the subsequent chapters. Chapter 2 reports empirical data on the functioning of two components of Baddeley’s WM model (1986): (1) the capacity of the phonological loop, also called verbal short-term memory (STM), and its automatic rehearsal capacity and (2) the central executive. Performance of children with MID (average chronological age of 15 years and an average IQ score of 70) was compared with typically developing children of the same chronological age (CA control; average chronological age of 15 years and an average IQ score of 100) and with younger, typically developing children of the same mental age (MA control; average chronological age of 10 years and an average IQ score of 100). In Chapter 3 verbal and visuo-spatial STM and WM in comparable groups was explored by use of an extensive task battery (see Chapter 1, Figure 1). Performance of children with MID was compared to that of the CA and MA control children. Furthermore, it was investigated if within the MID group subgroups exist with a unique WM profile each. Since WM is not only used in school based settings, but in everyday life as well, in Chapter 4 it was investigated how children with MID function on memory tasks in everyday life, and if those performances are related to their WM abilities. Finally, as WM is considered to be so important, it was investigated if WM can be trained effectively in children with MID. This is reported in Chapter 5. In the sixth and final Chapter of the thesis, the results of the above studies will be summarized and integrated. First, the study outcomes will be briefly introduced and summarized. Next, the general conclusions of the thesis will be addressed in which the research questions posed in Chapter 1 will be answered. Returning issues that had to be dealt with, raised by the author, co-workers and reviewers will be considered subsequently. Finally, the implications of the results for practice and directions for future research are discussed