A Comparative Study of Working Memory in Children
with Neurodevelopmental Disorders.
PhD thesis, National University of Ireland Maynooth.
Background: Previous research has provided conflicting reports with regards to the
functioning of the various components of working memory in children with
neurodevelopmental disorders, and in particular in those with autism. This research
was initiated to answer some of the questions raised by these research studies and to
provide a comparison of performance of children with different neurodevelopmental
disorders on the same measure of working memory.
Aim: The purpose of this research was to investigate working memory functioning of
children with neurodevelopmental disorders including autism spectrum disorder
(ASD), intellectual disability (ID), and specific and language impairment (SLI). A
group of typically developing (TD) children was also tested for comparison. The
groups included in the present study were selected with the aim of identifying varying
patterns or profiles of working memory dysfunction, as a function of the different
levels of intellectual functioning within these neurodevelopmental groups. The scores
of children with SLI were within the average range on the performance IQ scale
(PIQ). Low functioning children with ASD have a Full scale IQ (FSIQ) score of less
than 70; high functioning children with ASD have a Full Scale IQ score above 70.
Children with ID have a FSIQ score of lower than 70. Within each group, there can be
considerable variation in IQ score, allowing the examination of working memory as a
function of IQ. The research also aimed to explore the relationship between
intelligence and memory, with particular reference to crystallized and fluid
intelligence and processing speed. The present research study also aimed to examine
any particular working memory profiles that might characterise each group; these
were predicted to vary across groups. The hypotheses were generated based on
previous research in this field, which suggests that children with neurodevelopmental
difficulties demonstrate impairments in memory functioning, particularly affecting
working memory, compared to typically developing children.
Method: Data were collected from children in pre-schools and schools located in the
Munster region of the Republic of Ireland. In total, 96 children participated, with ages
ranging from 48 to 192 months. The ASD group consisted of 26 children (23 male; 3
female) with an age range of 49-161 months. The group with ID consisted of 32
children (21 male; 11 female), with an age range of 56-192 months. The SLI group
consisted of 15 children (10 male and 5 female) with an age range of 75-154 months.
The typically developing children consisted of 23 children (12 male and 11 female)
with an age range of 48-190 months. The SLI group had a lower age range when
compared to the other three groups; however, this would not have had any substantial
effect on the outcome of the results as the test batteries used in the research were age
normed. The children were assessed using the Wechsler Intelligence Scale for
Children-IV (WISC-IV) or the Wechsler Preschool and Primary Scale of Intelligence
(WPPSI-III), as appropriate for their age, to determine their level of intellectual
ability. The children with a diagnosis of ASD and SLI were assessed by the relevant
professionals to confirm their diagnosis. All children were subsequently assessed
using a measure of the components of working memory, the Automated Working
Memory Assessment (AWMA), in order to identify any relative strengths and
weaknesses in their working memory functioning.
Results: The results indicate that the high functioning children with ASD performed
equally well on almost all the subtests of AWMA when matched with the typically
developing children on IQ and age. There was no difference observed on the memory
tasks between the performance of low functioning children with ASD and those with
ID. The children with ID performed poorly on the memory tasks compared to the
children with average intelligence. The SLI group showed impairment on the verbal
memory measures and, when IQ was controlled, the SLI group indicated some further
impairment on visual spatial tasks when their performance was compared with the
typically developing children. Furthermore, these groups presented their own unique
profiles when Verbal Comprehension Index (VCI), Perceptual Reasoning Index (PRI)
and Processing Speed Index (PSI), measures that contribute towards calculating the
Full Scale IQ (FSIQ), were statistically controlled. The VCI and PRI are considered to
measure crystallized and fluid aspects of intelligence respectively. Correlational
analyses indicated a unique profile for each group.
Conclusion: The implications of the findings are discussed with reference to relevant
research and interventions for children with neurodevelopmental difficulties. The
present research highlights the differential performance of the four groups with
respect to working memory, and notes the contribution of intellectual functioning to
the memory dysfunction.
||Working Memory in Children; Neurodevelopmental Disorders;
||Faculty of Science and Engineering > Psychology
||17 Jun 2011 14:01
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