Charles Hulme

Is working memory training effective? A meta-analytic review

It has been suggested that working memory training programs are effective both as treatments for attention-deficit/hyperactivity disorder (ADHD) and other cognitive disorders in children and as a tool to improve cognitive ability and scholastic attainment in typically developing children and adults. However, effects across studies appear to be variable, and a systematic meta-analytic review was undertaken. To be included in the review, studies had to be randomized controlled trials or quasi-experiments without randomization, have a treatment, and have either a treated group or an untreated control group. Twenty-three studies with 30 group comparisons met the criteria for inclusion. The studies included involved clinical samples and samples of typically developing children and adults. Meta-analyses indicated that the programs produced reliable short-term improvements in working memory skills. For verbal working memory, these near-transfer effects were not sustained at follow-up, whereas for visuospatial working memory, limited evidence suggested that such effects might be maintained. More importantly, there was no convincing evidence of the generalization of working memory training to other skills (nonverbal and verbal ability, inhibitory processes in attention, word decoding, and arithmetic). The authors conclude that memory training programs appear to produce short-term, specific training effects that do not generalize. Possible limitations of the review (including age differences in the samples and the variety of different clinical conditions included) are noted. However, current findings cast doubt on both the clinical relevance of working memory training programs and their utility as methods of enhancing cognitive functioning in typically developing children and healthy adults.

Phonemes, rimes, vocabulary, and grammatical skills as foundations of early reading development: evidence from a longitudinal study.

The authors present the results of a 2-year longitudinal study of 90 British children beginning at school entry when they were 4 years 9 months old (range = 4 years 2 months to 5 years 2 months). The relationships among early phonological skills, letter knowledge, grammatical skills, and vocabulary knowledge were investigated as predictors of word recognition and reading comprehension. Word recognition skills were consistently predicted by earlier measures of letter knowledge and phoneme sensitivity (but not by vocabulary knowledge, rhyme skills, or grammatical skills). In contrast, reading comprehension was predicted by prior word recognition skills, vocabulary knowledge, and grammatical skills. The results are related to current theories about the role of phonological, grammatical, and vocabulary skills in the development of early reading skills.

Oscillator-based memory for serial order

A computational model of human memory for serial order is described (OSCillator-based Associative Recall [OSCAR]). In the model, successive list items become associated to successive states of a dynamic learning-context signal. Retrieval involves reinstatement of the learning context, successive states of which cue successive recalls. The model provides an integrated account of both item memory and order memory and allows the hierarchical representation of temporal order information. The model accounts for a wide range of serial order memory data, including differential item and order memory, transposition gradients, item similarity effects, the effects of item lag and separation in judgments of relative and absolute recency, probed serial recall data, distinctiveness effects, grouping effects at various temporal resolutions, longer term memory for serial order, list length effects, and the effects of vocabulary size on serial recall.

Phonological skills and their role in learning to read: A meta-analytic review.

The authors report a systematic meta-analytic review of the relationships among 3 of the most widely studied measures of childrens phonological skills (phonemic awareness, rime awareness, and verbal short-term memory) and childrens word reading skills. The review included both extreme group studies and correlational studies with unselected samples (235 studies were included, and 995 effect sizes were calculated). Results from extreme group comparisons indicated that children with dyslexia show a large deficit on phonemic awareness in relation to typically developing children of the same age (pooled effect size estimate: -1.37) and children matched on reading level (pooled effect size estimate: -0.57). There were significantly smaller group deficits on both rime awareness and verbal short-term memory (pooled effect size estimates: rime skills in relation to age-matched controls, -0.93, and reading-level controls, -0.37; verbal short-term memory skills in relation to age-matched controls, -0.71, and reading-level controls, -0.09). Analyses of studies of unselected samples showed that phonemic awareness was the strongest correlate of individual differences in word reading ability and that this effect remained reliable after controlling for variations in both verbal short-term memory and rime awareness. These findings support the pivotal role of phonemic awareness as a predictor of individual differences in reading development. We discuss whether such a relationship is a causal one and the implications of research in this area for current approaches to the teaching of reading and interventions for children with reading difficulties.

Speech rate and the development of short-term memory span

Abstract Two experiments are reported which examine the effects of word duration on memory span in subjects of different ages. The same linear function relating recall to speech rate (assessed by the speed of repeating words) fits the results of subjects ranging in age from 4 years old to adulthood. It is concluded that developmental increases in short-term memory span can be explained in terms of increases in speech rate and that there is no evidence for an increase in short-term memory capacity. Analyses of the childrens speech suggests that increases in speech rate with age reflect increases in the speed of articulation of individual words, rather than any change in the duration of pauses between successive words or changes in coarticulation between words.

The development of phonological awareness in preschool children

A short-term longitudinal study was carried out on a group of 67 preschool children. At three points in time over a 12-month period, the children were given tests measuring their syllable, rime, and phoneme awareness, speech and language skills, and letter knowledge. In general, childrens rime skills developed earlier than their phoneme skills. Structural equation models showed that articulatory skills and syllable and rime awareness predicted later phoneme awareness.

Concrete words are easier to recall than abstract words : Evidence for a semantic contribution to short-term serial recall

Immediate serial recall and maximal speech rate were assessed for concrete and abstract words differing in length. Experiment 1 showed large advantages for spoken recall of concrete words that were independent of speech rate. Experiment 2 showed an equivalent effect with written, rather than spoken, recall. Experiment 3 showed that the concreteness effect was still present when recall was backward rather than forward. In all 3 experiments, concrete words enjoyed an advantage that was roughly constant across all serial positions (with the possible exception of the 1st and last items). Experiment 4 used a matching-span procedure and showed that when there was no requirement for linguistic output, the effect of concreteness (but not the effect of word length) was eliminated. It is argued that semantic coding exerts powerful effects in verbal short-term memory tasks that have generally been underestimated. (PsycINFO Database Record (c) 2007 APA, all rights reserved) (journal abstract).

Neural systems predicting long-term outcome in dyslexia

Individuals with developmental dyslexia vary in their ability to improve reading skills, but the brain basis for improvement remains largely unknown. We performed a prospective, longitudinal study over 2.5 y in children with dyslexia (n = 25) or without dyslexia (n = 20) to discover whether initial behavioral or brain measures, including functional MRI (fMRI) and diffusion tensor imaging (DTI), can predict future long-term reading gains in dyslexia. No behavioral measure, including widely used and standardized reading and language tests, reliably predicted future reading gains in dyslexia. Greater right prefrontal activation during a reading task that demanded phonological awareness and right superior longitudinal fasciculus (including arcuate fasciculus) white-matter organization significantly predicted future reading gains in dyslexia. Multivariate pattern analysis (MVPA) of these two brain measures, using linear support vector machine (SVM) and cross-validation, predicted significantly above chance (72% accuracy) which particular child would or would not improve reading skills (behavioral measures were at chance). MVPA of whole-brain activation pattern during phonological processing predicted which children with dyslexia would improve reading skills 2.5 y later with >90% accuracy. These findings identify right prefrontal brain mechanisms that may be critical for reading improvement in dyslexia and that may differ from typical reading development. Brain measures that predict future behavioral outcomes (neuroprognosis) may be more accurate, in some cases, than available behavioral measures.

Reading Comprehension Difficulties in Children: The Role of Language Comprehension and Working Memory Skills.

This paper reports two studies investigating the nature of comprehension deficits in a group of 7–8 year old children whose decoding skills are normal, but whose reading comprehension skills are poor. The performance of these poor comprehenders was compared to two control groups, Chronological-Age controls and Comprehension-Age controls. The first study examined whether these comprehension difficulties are specific to reading. On two measures of listening comprehension the poor comprehenders were found to perform at a significantly lower level than Chronological-Age controls. However, they did not differ from a group of younger children matched for reading comprehension skills. This indicates that the observed comprehension difficulties are not restricted to reading, but rather represent a general comprehension limitation. The second study investigated whether these comprehension difficulties can be explained in terms of a memory deficit. The short-term and working memory skills of these three groups were examined. The poor comprehenders did not differ from their Chronological-Age controls on either of these tasks. In conclusion, it is argued that working memory processes are not a major causal factor in the creation of the comprehension difficulties identified in the present group of poor comprehenders.

Words, nonwords, and phonological processes: Some comments on Gathercole, Willis, Emslie, and Baddeley

Gathercole, Willis, Emslie, and Baddeley (1991) present a reanalysis of some of their earlier data concerned with the relationship between nonword repetition and the development of vocabulary knowledge in young children. In the present article we outline some theoretical differences between ourselves and this group in the interpretation of nonword repetition and discuss how best these differences could be resolved.