Procedural and Declarative Memory and Language Ability in Children

340 Pages·2017·4.38 MB·English

by  Gill West

Procedural and Declarative Memory
and Language Ability in Children

Gillian West
University College London

A thesis submitted for the
degree of Doctor of Philosophy (PhD)

November 2017
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Declaration

I, Gillian West, confirm that the work presented in this thesis is my own. Where
information has been derived from other sources, I confirm that this has been
indicated in the thesis.

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Abstract
Impaired procedural learning has been suggested as a possible cause of
developmental language disorder and dyslexia (Nicolson & Fawcett, 2007; Ullman &
Pierpont, 2005). However, studies investigating this hypothesis have so far delivered
inconsistent results. These studies typically use extreme group designs, frequently with
small sample sizes and measures of procedural learning with unreported reliability.
This thesis first used a meta-analysis to examine the existing evidence for a
procedural deficit in language disorders. The experimental studies then took a different
approach to previous studies, using a concurrent correlational design to test large
samples of children unselected for ability on a wide range of implicit (serial reaction
time, Hebb serial learning, contextual cueing and probabilistic category learning) and
declarative learning tasks and literacy, language and arithmetic attainment measures.
The reliability of the tasks was also carefully assessed. A final study explored the
hypothesis from an extreme group design perspective, comparing a typically
developing sample with a group of dyslexic children matched for reading ability. None
of the studies found evidence of a relationship between procedural learning and
language-related abilities. By contrast, a relationship between verbal declarative
learning and attainment was found replicating earlier studies. Crucially, the first large-
scale study showed that procedural learning tasks of a similar length to those typically
used in earlier studies had unacceptably low reliability and correlated poorly with each
other and with attainment. The second large-scale study, used extended procedural
learning tasks that had proved reliable in adults, but found similar low levels of
reliability in children. Additionally, the level of attention children paid during these
extended tasks accounted entirely for the relationship between procedural learning and
attainment.
The results in this thesis highlight the importance of establishing task reliability, as
well as considering the potential effects of individual differences in basic cognitive
processes such as attention in all investigations of procedural learning.

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Acknowledgements
First and foremost, I would like to thank my supervisor Professor Charles Hulme
for such tremendous guidance and support throughout the last three years, for shaping
this thesis, alongside my development as a researcher, and for making my time at UCL
such an enriching experience. Thank you also to my secondary supervisor Professor
David Shanks for his support and insightful comments on papers and on the draft of
this thesis. I would also like to acknowledge my gratitude to the ESRC for the funding
I received that enabled me to undertake this PhD.
I want to thank several people who have been integral to my success during my
time at UCL. Thank you to Miguel Vadillo for his programming skill and support on
the contextual cueing and weather prediction tasks. His enthusiasm for cognitive
psychology and the investigation of procedural learning has been contagious. Thank
you to Mike Coleman for the expert programming of the serial reaction time task that
forms the backbone of this thesis. I have also been lucky to be part of a very special
and supportive community of PhD students, postdocs and lecturers at UCL and I thank
them all, but I am particularly grateful to Francina Clayton who was unfailingly helpful
and full of good advice. My gratitude also goes to the head teachers and teachers who
welcomed me into their schools and the many wonderful, interested and interesting
children who took part in the research.
Last, but by no means least, I would like to thank my lovely family for giving me the
courage to start this PhD and see it through to the end. Your confidence in me has
made all the difference. I thank my parents and brother for their unwavering and
unquestioning love and support, always. I thank my husband, James, for his love and
patience and for putting up with so many lost evenings and weekends. He has been my
partner in this adventure, as in all things. I thank my children, Alice and Casper, for
surviving three years of benign neglect with such good humour. You are still and
always the best things I have ever done. I will pay more attention to you now, I
promise.

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For my family

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Table of Contents
Chapter 1 Developmental disorders of language .................................................... 21
1.1 Developmental language disorder .............................................................. 21
1.2 Developmental dyslexia ............................................................................. 22
1.3 Developmental language disorder & dyslexia are distinct disorders ......... 23
1.4 Both disorders are dimensional .................................................................. 25
1.5 Heterogeneity ............................................................................................. 25
1.6 Comorbidity with other developmental disorders ...................................... 25
1.7 Genetic and environmental factors............................................................. 26
1.8 The biological basis of developmental language disorder and dyslexia .... 28
1.9 Causal explanations of developmental language disorder ......................... 30
1.9.1 Language specific accounts of developmental language disorder ......... 31
1.9.2 Cognitive level explanations of developmental language disorder........ 32
1.10 Causal explanations of dyslexia ................................................................. 33
1.10.1 A core phonological deficit ................................................................ 33
1.10.2 Phonological short-term memory ....................................................... 35
1.10.3 Other causal explanations of dyslexia ................................................ 35
Chapter 2 Implicit and Explicit memory ................................................................ 39
2.1 Multiple Memory Systems ......................................................................... 39
2.1.1 Multiple Memory Systems Taxonomy .................................................. 39
2.1.2 Declarative memory and learning .......................................................... 41
2.1.3 Non-declarative memory and learning ................................................... 42
2.2 Evidence for multiple memory systems ..................................................... 45
2.2.1 Evidence from Alzheimer’s disease and schizophrenia ......................... 47
2.2.2 Evidence from diseases of the basal ganglia .......................................... 48
2.2.3 Demonstrations in normal participants .................................................. 49
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2.2.4 Age and IQ independence ...................................................................... 50
2.3 Interaction and Competition ....................................................................... 51
2.4 Other accounts of the organization of memory .......................................... 52
Chapter 3 The Procedural Deficit Hypothesis ........................................................ 58
3.1 Summary of the hypothesis ........................................................................ 58
3.2 The neural basis for the procedural deficit hypothesis ............................... 59
3.2.1 The basal ganglia .................................................................................... 59
3.2.2 Broca’s area ............................................................................................ 60
3.2.3 The cerebellum ....................................................................................... 61
3.3 Measures of implicit learning ..................................................................... 62
3.3.1 The serial reaction time task (SRT) ........................................................ 63
3.3.2 Hebb serial order learning task ............................................................... 67
3.3.3 Artificial grammar and statistical learning ............................................. 69
3.3.4 Probabilistic category learning ............................................................... 72
3.3.5 Contextual cueing ................................................................................... 74
3.3.6 Different metrics to measure implicit learning ...................................... 76
3.4 Declarative memory and the distinction between short-term and long-term
memory ................................................................................................................... 79
3.4.1 Neural evidence ...................................................................................... 81
3.4.2 Behavioural evidence ............................................................................. 82
3.4.3 The processing view of short-term and long-term memory ................... 83
Chapter 4 Meta-analyses ......................................................................................... 85
4.1 Previous reviews of the procedural deficit hypothesis ............................... 85
4.2 Methodology and inclusion criteria ............................................................ 88
4.3 Search Strategy ........................................................................................... 89
4.4 Procedure .................................................................................................... 92
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