Working memory, reading, and mathematical skills in children with developmental coordination disorder

The aim of the present study was investigate the relationship between working memory and reading and mathematical skills in 55 children diagnosed with developmental coordination disorder (DCD). The findings indicate a pervasive memory deficit in all memory measures. In particular, deficits observed in visuospatial short-term and working memory tasks were significantly worse than in the verbal short-term memory ones. On the basis of these deficits, the sample was divided into high and low visuospatial memory ability groups. The low visuospatial memory group performed significantly worse on the attainment measures compared to the high visuospatial memory group, even when the contribution of IQ was taken into account. When the sample was divided into high and low verbal working memory ability groups, verbal working memory skills made a unique contribution to attainment only when verbal IQ was taken into account, but not when performance IQ was statistically controlled. It is possible that the processing demands of the working memory tasks together with the active motor component reflected in the visuospatial memory tasks and performance IQ subtest both play a crucial role in learning in children with DCD.     

Modelling relations between sensory processing, speech perception, orthographic and phonological ability, and literacy achievement

The general magnocellular theory postulates that dyslexia is the consequence of a multimodal deficit in the processing of transient and dynamic stimuli. In the auditory modality, this deficit has been hypothesized to interfere with accurate speech perception, and subsequently disrupt the development of phonological and later reading and spelling skills. In the visual modality, an analogous problem might interfere with literacy development by affecting orthographic skills. In this prospective longitudinal study, we tested dynamic auditory and visual processing, speech-in-noise perception, phonological ability and orthographic ability in 62 five-year-old preschool children. Predictive relations towards first grade reading and spelling measures were explored and the validity of the global magnocellular model was evaluated using causal path analysis. In particular, we demonstrated that dynamic auditory processing was related to speech perception, which itself was related to phonological awareness. Similarly, dynamic visual processing was related to orthographic ability. Subsequently, phonological awareness, orthographic ability and verbal short-term memory were unique predictors of reading and spelling development.     

Individual differences in proactive interference in verbal and visuospatial working memory

Proactive interference (PI) has been shown to affect working memory (WM) span as well as the predictive utility of WM span measures. However, most of the research on PI has been conducted using verbal memory items, and much less is known about the role of PI in the visuospatial domain. In order to further explore this issue, the present study used a within-subjects manipulation of PI that alternated clusters of trials with verbal and visuospatial to-be-remembered items. Although PI was shown to build and release across trials similarly in the two domains, important differences also were observed. The ability of verbal WM to predict performance on a measure of fluid intelligence was significantly affected by the amount of PI present, consistent with past research, but this proved not to be the case for visuospatial WM. Further, individuals’ susceptibility to PI in one domain was relatively independent of their susceptibility in the other domain, suggesting that, contrary to some theories of executive function, individual differences in PI susceptibility may not be domain-general.     

The generality of working memory capacity: a latent-variable approach to verbal and visuospatial memory span and reasoning

A latent-variable study examined whether verbal and visuospatial working memory (WM) capacity measures reflect a primarily domain-general construct by testing 236 participants in 3 span tests each of verbal WM. visuospatial WM, verbal short-term memory (STM), and visuospatial STM. as well as in tests of verbal and spatial reasoning and general fluid intelligence (Gf). Confirmatory' factor analyses and structural equation models indicated that the WM tasks largely reflected a domain-general factor, whereas STM tasks, based on the same stimuli as the WM tasks, were much more domain specific. The WM construct was a strong predictor of Gf and a weaker predictor of domain-specific reasoning, and the reverse was true for the STM construct. The findings support a domain-general view of WM capacity, in which executive-attention processes drive the broad predictive utility of WM span measures, and domain-specific storage and rehearsal processes relate more strongly to domain-specific aspects of complex cognition.     

Kindergarten predictors of three aspects of reading achievement

Kindergarten measures of intelligence, auditory perception, visual perception, and associative learning were used to predict three aspects of reading achievement (word attack, word recognition, and comprehension) at the end of Grades 1,2, and 3 for 79 subjects. The predictability of each measure was a function not only of grade, but also of the aspect of reading achievement being predicted. Multiple correlations of the predictors tended to increase across grade levels and were highest for the comprehension aspect of reading. The Number Facility subtest of the PMA was the over-all best predictor or reading achievement. Possible reasons for this and other findings are discussed.     

Unexpected reading precocity in a normal preschooler: implications for hyperlexia

This is a case study of a left-handed, preschool boy of superior intelligence who read very early and at a level well beyond what his IQ would predict. He is developmentally normal with no signs of autism or related disorders. His reading age was 9.3 at age 2-11 and 11.2 at 4-2; these levels are considerably beyond what would be predicted by his IQ or language age. He was able to read nonwords and both regular and irregular words equally well, indicating his mechanisms of lexical access in reading are similar to those of normal readers. Unlike classical hyperlexics, his reading comprehension for both single words and sentences was well above age level. When his precocious reading first appeared, he was also advanced in reading-related linguistic skills, such as phoneme awareness, auditory verbal short-term memory, and word retrieval, but not in visuospatial skills. These results imply that neither pathological language and/or social development, nor pathological variation in the normal mechanisms of lexical access in reading are necessary causes for reading precocity in early childhood. A model for integrating subtypes of precocious readers with subtypes of normal and dyslexic readers is proposed.     

Inspection time and its relation to intelligence

Inspection time, defined as the minimum duration for which two different stimuli must be presented if they are to be perceived as different, was measured for both auditory and visual stimuli. The minimum durations were determined by means of a two- alternative forced-choice task for 50 children whose average age was 12 years 2 months. The times were correlated with the children's verbal (Mill-Hill vocabulary) and nonverbal (Raven matrices) intelligence. The Kendall correlation coefficients were ?.3188 and ?.0929 for the auditory and visual inspection times with verbal intelligence, and ?.2322 and ?.2676 for those times with nonverbal intelligence. Auditory and visual inspection times were correlated .1721 with each other. These results do not support earlier claims that inspection time is closely related to conventional measures of intelligence.     

英语学习不良儿童语音能力与阅读理解的关系

探讨了英语学习不良儿童语音能力的发展状况,分析了这些儿童在英语学习中语音能力,句法意识及阅读理解能力间的关系。结果发现,除了在假词拼读能力上存在缺陷外,英语学习不良儿童在其他语音能力--英语语音意识、听觉言语工作记忆及视觉言语工作记忆上均不存在发展滞后现象;在对儿童的阅读理解能力进行预测时,假词拼读、语音意识、句法意识和听觉工作记忆是较好的预测效标。     

Speech perception in preschoolers at family risk for dyslexia: relations with low-level auditory processing and phonological ability

We tested categorical perception and speech-in-noise perception in a group of five-year-old preschool children genetically at risk for dyslexia, compared to a group of well-matched control children and a group of adults. Both groups of children differed significantly from the adults on all speech measures. Comparing both child groups, the risk group presented a slight but significant deficit in speech-in-noise perception, particularly in the most difficult listening condition. For categorical perception a marginally significant deficit was observed on the discrimination task but not on the identification task. Speech parameters were significantly related to phonological awareness and low-level auditory measures. Results are discussed within the framework of a causal model where low-level auditory problems are hypothesized to result in subtle speech perception problems that might interfere with the development of phonology and reading and spelling ability.     

Working memory in children with reading disabilities

This study investigated associations between working memory (measured by complex memory tasks) and both reading and mathematics abilities, as well as the possible mediating factors of fluid intelligence, verbal abilities, short-term memory (STM), and phonological awareness, in a sample of 46 6- to 11-year-olds with reading disabilities. As a whole, the sample was characterized by deficits in complex memory and visuospatial STM and by low IQ scores; language, phonological STM, and phonological awareness abilities fell in the low average range. Severity of reading difficulties within the sample was significantly associated with complex memory, language, and phonological awareness abilities, whereas poor mathematics abilities were linked with complex memory, phonological STM, and phonological awareness scores. These findings suggest that working memory skills indexed by complex memory tasks represent an important constraint on the acquisition of skill and knowledge in reading and mathematics. Possible mechanisms for the contribution of working memory to learning, and the implications for educational practice, are considered.     

Neuropsychological functioning in a patient with essential tremor with and without bilateral VIM stimulation

The effects of deep brain stimulation on motor functions, cognitive abilities, and mood were assessed in an 80-year-old, right-handed male with a chronic history of essential tremor. Electrodes were implanted bilaterally in the ventral intermediate nucleus of the thalamus during a single operation. Upon evaluation at 3 months postsurgery, bilateral stimulation was associated with a clinically significant reduction in tremor ratings and improvement in manual dexterity. At that time, a battery of neuropsychological measures was administered with and without bilateral stimulation. The patient demonstrated comparable performances on measures of visuospatial perception, attention, mental tracking, verbal learning, and verbal recognition memory in both the "on" and "off" conditions. Without stimulation, the patient demonstrated declines of greater than 1 SD on measures of verbal fluency and verbal recall compared to when the stimulators were active. Responses to mood rating scales also indicated greater subjective distress without stimulation. Results are discussed in the context of previous studies of the effects of thalamic stimulation on neurocognitive functioning.     

The intelligence of the Mongoloids: A psychometric, evolutionary and neurological theory

This paper presents a theory of the intelligence of the Mongoloids consisting of three linked sub-theories. The first concerns the psychometric features of Mongoloid intelligence and proposes that Mongoloids are characterised by high general intelligence (Spearman's g), high visuospatial abilities and low verbal abilities. Mongoloid abilities also display slow maturation in infancy and early childhood. It is proposed that this pattern of abilities cannot be explained in environmental terms and should be regarded as substantially genetically programmed. The second sub-theory presents an evolutionary explanation for this pattern of abilities in Mongoloids, whereby it is proposed that the extreme cold of the ice ages acted as a selection pressure for increases in Spearman's g and the visuospatial abilities. The low verbal abilities and slow maturation rates are interpreted as by-products of these adaptations. The third sub-theory presents a neurological model for the Mongoloid brain in which it is proposed that cortex devoted to the visuospatial abilities was expanded at the expense of the cortex devoted to the verbal abilities. The implication that there exists a negative correlation between the visuospatial abilities and the verbal abilities is considered in the concluding part of the paper and shown to be correct.     

The influence of strategies on relationships between working memory and cognitive skills

The aim of this study was to test the effect of administration method on relationships between working memory span tasks and cognitive skills. Participants completed both participant-administered and experimenter-administered working memory measures in both verbal and visuospatial domains. Although the tasks were equally reliable, the additional time taken to implement strategies in the participant-administered tasks in the verbal domain reduced the correlations between working memory and reading comprehension and arithmetic. These findings did not extend to a visuospatial working memory measure, for which there was no significant difference between the participant-administered and experimenter-administered tasks in terms of their relationships with comprehension and arithmetic. However, performance on experimenter-administered working memory tasks in both verbal and visuospatial domains predicted unique variance in comprehension and arithmetic while controlling for scores on the participant-administered tasks. The results are discussed in terms of theoretical and practical implications for working memory research.     

The influence of strategies on relationships between working memory and cognitive skills

The aim of this study was to test the effect of administration method on relationships between working memory span tasks and cognitive skills. Participants completed both participant-administered and experimenter-administered working memory measures in both verbal and visuospatial domains. Although the tasks were equally reliable, the additional time taken to implement strategies in the participant-administered tasks in the verbal domain reduced the correlations between working memory and reading comprehension and arithmetic. These findings did not extend to a visuospatial working memory measure, for which there was no significant difference between the participant-administered and experimenter-administered tasks in terms of their relationships with comprehension and arithmetic. However, performance on experimenter-administered working memory tasks in both verbal and visuospatial domains predicted unique variance in comprehension and arithmetic while controlling for scores on the participant-administered tasks. The results are discussed in terms of theoretical and practical implications for working memory research.     

Adaptive n-back training does not improve fluid intelligence at the construct level: Gains on individual tests suggest that training may enhance visuospatial processing

Short-term adaptive cognitive training based on the n-back task is reported to increase scores on individual ability tests, but the key question of whether such increases generalize to the intelligence construct is not clear. Here we evaluate fluid/abstract intelligence (Gf), crystallized/verbal intelligence (Gc), working memory capacity (WMC), and attention control (ATT) using diverse measures, with equivalent versions, for estimating any changes at the construct level after training. Beginning with a sample of 169 participants, two groups of twenty-eight women each were selected and matched for their general cognitive ability scores and demographic variables. Under strict supervision in the laboratory, the training group completed an intensive adaptive training program based on the n-back task (visual, auditory, and dual versions) across twenty-four sessions distributed over twelve weeks. Results showed that this group had the expected systematic improvements in n-back performance over time; this performance systematically correlated across sessions with Gf, Gc, and WMC, but not with ATT. However, the main finding showed no significant changes in the assessed psychological constructs for the training group as compared with the control group. Nevertheless, post-hoc analyses suggested that specific tests and tasks tapping visuospatial processing might be sensitive to training.     

Knox's cube imitation test: a historical review and an experimental analysis

The cube imitation test was developed by as a nonverbal test of intelligence. Many variants show satisfactory reliability, but performance is correlated both with Verbal IQ and with Performance IQ. Performance is impaired by cerebral lesions but unrelated to the side of lesion. Examinees describe both verbal and visuospatial strategies. In a new experiment, performance was disrupted by concurrent random generation, manual tapping, and articulatory suppression. The cube imitation test is not simply a measure of the ability to retain visuospatial information but also depends on verbal representations as well as attentional capacity. Even so, the test was central to the modern appreciation that any adequate measure of intelligence must incorporate both verbal tests and performance tests.     

Lexical effects on speech perception in individuals with "autistic" traits

It has been claimed that Autism Spectrum Disorder (ASD) is characterized by a limited ability to process perceptual stimuli in reference to the contextual information of the percept. Such a connection between a nonholistic processing style and behavioral traits associated with ASD is thought to exist also within the neurotypical population albeit in a more subtle way. We examined this hypothesis with respect to auditory speech perception, by testing whether the extent to which phonetic categorization shifts to make the percept a known word (i.e., the 'Ganong effect') is weakened as a function of autistic traits in neurotypicals. Fifty-five university students were given the Autism-Spectrum Quotient (AQ) and a segment identification test using two word-to-nonword Voice Onset Time (VOT) continua (kiss-giss and gift-kift). A significant negative correlation was found between the total AQ score and the identification shift that occurred between the continua. The AQ score did not correlate with scores on separately administered VOT discrimination, auditory lexical decision, or verbal IQ, thus ruling out enhanced auditory sensitivity, slower lexical access or verbal intelligence as explanations of the AQ-related shift in phonetic categorization.     

Variations in hand position, cerebral lateralization, and reading ability among right-handed children

A group of 121 right-handed children between the ages of 7 and 9 with a range of hand positions between normal and inverted were assessed for verbal and visuospatial lateralization and reading comprehension. Results indicate that (a) children with a normal hand position tended to be more verbally lateralized than children with nonnormal positions, although the effect was not strong or always consistent, (b) the closer the child was to the normal position, the higher the child's reading scores, and (c) poor readers were as lateralized for verbal and visuospatial functions as were good readers. Coupled with the results of previous research, these findings suggest that hand position indexes both maturation and lateralization, and that the relationship between hand position and reading is primarily mediated by the former.     

Early experience of sex hormones as a predictor of reading, phonology, and auditory perception

Previous research has indicated possible reciprocal connections between phonology and reading, and also connections between aspects of auditory perception and reading. The present study investigates these associations further by examining the potential influence of prenatal androgens using measures of digit ratio (the ratio of the lengths of the index and ring fingers). Those with low digit ratios (shorter index finger and therefore in the masculine direction) are hypothesised to have experienced greater "masculinisation" in the uterus. ANCOVA analyses using a verbal reasoning task as a covariate showed that only phonology was influenced by digit ratio in the right hand indicating that hypothesised androgen effects were inhibiting phonology; however this effect in the left hand was reduced and instead there was an effect indicating an inhibition of androgens on reading. Furthermore, subjects with low right-hand digit ratios were also impaired compared to those with high right-hand digit ratios in an auditory saltation task. These findings are discussed in terms of the possible effects of androgens on early brain development impairing aspects of the temporal processing of sounds by the left hemisphere, which could also have a secondary influence on developing phonology and literacy skills.     

Flexibility of working memory encoding in a sentence–picture–sound verification task

Dual-process accounts of working memory have suggested distinct encoding processes for verbal and visual information in working memory, but encoding for nonspeech sounds (e.g., tones) is not well understood. This experiment modified the sentence–picture verification task to include nonspeech sounds with a complete factorial examination of all possible stimulus pairings. Participants studied simple stimuli–pictures, sentences, or sounds–and encoded the stimuli verbally, as visual images, or as auditory images. Participants then compared their encoded representations to verification stimuli–again pictures, sentences, or sounds–in a two-choice reaction time task. With some caveats, the encoding strategy appeared to be as important or more important than the external format of the initial stimulus in determining the speed of verification decisions. Findings suggested that: (1) auditory imagery may be distinct from verbal and visuospatial processing in working memory; (2) visual perception but not visual imagery may automatically activate concurrent verbal codes; and (3) the effects of hearing a sound may linger for some time despite recoding in working memory. We discuss the role of auditory imagery in dual-process theories of working memory.