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1.
Executive Functions in Young Children with Autism   总被引：17，自引：0，他引：17  
The executive dysfunction hypothesis of autism has received support from most studies of older people with autism; however, studies of young children have produced mixed results. Two studies are presented that compare the performance of preschoolers with autism (mean = 51 months/4.3 years of age) to a control group matched on age, and verbal and nonverbal ability. The first study (n = 18 autism and 17 control) found no group differences in performance on 8 executive function tasks (A not B, Object Retrieval, A not B with Invisible Displacement, 3-Boxes Stationary and Scrambled, 6-Boxes Stationary and Scrambled, and Spatial Reversal), but did find that children with autism initiated fewer joint attention and social interaction behaviors. The second (longitudinal) study of a subset of the children (n = 13 autism and 11 control) from the first study found that neither groups' performance on Spatial Reversal changed significantly over the course of a year. The results of these studies pose a serious challenge to the executive dysfunction hypothesis of autism.  相似文献   

2.
Intact and Impaired Memory Functions in Autism   总被引：21，自引：0，他引：21  
This study examined memory functions in individuals with autism. Based on previous evidence of executive function (EF) deficits, we hypothesized that subjects with autism would demonstrate a pattern of intact and imparred memory functions similar to that found in other groups with EF deficits, such as patients with frontal lobe pathology. We compared the performance of high-functioning children and adolescents with autism (n = 19) and clinical comparison subjects (n = 19) matched on sex, CA, and VIQ on measures of memory and EF. The group with autism performed significantly worse than comparison subjects on measures of temporal order memory, source memory, supraspan free recall, working memory, and EF, but not on short- and long-term recognition, cued recall, or new learning ability, consistent with the predictions of the EF theory. The cognitive measures were significantly more intercorrelated in the autism group than the comparison group, consistent with a limit in central cognition.  相似文献   

3.
Neuropsychological Correlates of Early Symptoms of Autism   总被引：8，自引：0，他引：8  
Both the medial temporal lobe and dorsolateral prefrontal cortex have been implicated in autism. In the present study, performance on two neuropsychological tasks—one tapping the medial temporal lobe and related limbic structures, and another tapping the dorsolateral prefrontal cortex—was examined in relation to performance on tasks assessing autistic symptoms in young children with autism, and developmentally matched groups of children with Down syndrome or typical development. Autistic symptoms included orienting to social stimuli, immediate and deferred motor imitation, shared attention, responses to emotional stimuli, and symbolic play. Compared with children with Down syndrome and typically developing children, children with autism performed significantly worse on both the medial temporal lobe and dorsolateral prefrontal tasks, and on tasks assessing symptoms domains. For children with autism, the severity of autistic symptoms was strongly and consistently correlated with performance on the medial temporal lobe task, but not the dorsolateral prefrontal task. The hypothesis that autism is related to dysfunction of the medial temporal lobe and related limbic structures, such as the orbital prefrontal cortex, is discussed.  相似文献   

4.
This study explored the hypothesis that children with early-treated phenylketonuria (PKU) are selectively impaired on executive function measures, even when still on diet. The rationale for this hypothesis is that even mild elevations in phenylalanine (Phe) can lead to lower central levels of biogenic amines, including dopamine (DA). We hypothesize that this mild DA depletion causes subtle prefrontal dysfunction, which in turn affects executive functions such as set maintenance, planning, and organized search. 11 preschool early-treated PKU children (M age = 4.64) and a sample of age- and IQ-matched unaffected peers (n = 11) were evaluated on a battery of executive function (EF) measures. In addition, a "non-executive function" task, recognition memory, was administered to all subjects. Group comparisons demonstrated that PKU children were significantly impaired on an executive function composite score; there were no group differences, however, in recognition memory. These results supported the hypothesized specific deficit in executive function. Furthermore, within the PKU group the executive function composite score was significantly negatively correlated with concurrent phenylalanine levels, even after controlling for the correlation between IQ and executive function skills. This second finding provides support for the proposed biochemical mechanism underlying the specific cognitive deficits.  相似文献   

5.
Studies have shown that young children with autism are not impaired on prefrontal tasks relative to what would be expected for their mental age, raising questions about the executive dysfunction hypothesis of autism. These studies did not include ventromedial prefrontal tasks, however. The present study examined whether young children with autism spectrum disorder (ASD) are impaired on ventromedial prefrontal tasks, and whether performance on such tasks is correlated with a core autism symptom, joint attention ability. Seventy-two 3- to 4-year-old children with ASD, 34 3- to 4-year-old developmentally delayed children, and 39 12- to 46-month-old typically developing children, matched on mental age, were administered ventromedial and dorsolateral prefrontal tasks and joint attention tasks. Children with ASD performed similarly to comparison groups on all executive function tasks, indicating that at this early age, there is no autism-specific pattern of executive dysfunction. Ventromedial, but not dorsolateral, prefrontal task performance was strongly correlated with joint attention ability, however. The ventromedial prefrontal cortex is hypothesized to play a role in the development of joint attention and possibly some aspects of the autistic syndrome.  相似文献   

6.
The purpose of this study was to investigate whether changes in working memory (WM) of children with reading disabilities (RD) were related to a domain-specific or a domain-general system. Based on Daneman and Carpenter's (1980) Sentence Listening Span task, children were subgrouped into a group of high executive processing (high listening span) children without RD, a group of low executive processing (low listening span) children with RD, and a group of children with and without RD matched on executive processing (moderate listening span). Subgroups were compared on phonological, visual-spatial, and semantic WM tasks across initial (no probes or cues), gain (cues that bring performance to an asymptotic level), and maintenance conditions (asymptotic conditions without cues). The results showed that (a) children without RD high in executive processing ability outperformed all other subgroups, (b) the RD subgroup low in executive processing performed poorly relative to all other subgroups across task and memory conditions, (c) children with and without RD matched on executive processing were comparable in WM span and changes in WM for all tasks, and (d) WM performance of children with RD was a strong linear function of the high executive processing group, suggesting that the nature or the specific componential makeup of the tasks are not the main contributors to WM performance. Taken together, the results suggest that a domain-general system may partially contribute to poor WM in children with RD, and that this system may operate independently of their reading deficits.  相似文献   

7.
Dyslexia and the double deficit hypothesis   总被引：1，自引：4，他引：1  
The double deficit hypothesis (Bowers and Wolf 1993) maintains that children with both phonological and naming-speed deficits will be poorer readers than children with just one or neither of these deficits. In the present study, we drew on this hypothesis to help understand why some children have a serious reading impairment. In addition, by adding an orthographic factor, we extended it to a triple deficit hypothesis. Participants were 90 children aged 6 to 10 years. Dyslexic children, whose reading was low for age and for expected level, garden-variety poor readers, reading-level matched younger children, and low verbal IQ good readers, were compared. The dyslexic group was significantly lower then the garden-variety poor readers and the low verbal IQ good readers on most measures, and lower than the younger group on phonological measures. Findings support the double deficit hypothesis of Bowers and Wolf, and also the triple deficit hypothesis. Most of the poorest readers, nearly all of whom qualified as dyslexic, had a double or triple deficit in phonological, naming-speed, and orthographic skills. Conclusions were that dyslexia results from an overload of deficits in skills related to reading, for which the child cannot easily compensate.  相似文献   

8.
It is now thought that the cerebellum is involved in the acquisition of “language dexterity” in addition to its established role in motor skill acquisition and execution. Mild cerebellar impairment, therefore, provides a possible explanation of a range of problems shown by children with dyslexia. The authors have established suggestive evidence in support of this hypothesis in tests of balance and of time estimation. In a further test of the hypothesis, a battery of clinical tests for cerebellar impairment, including tests of muscle tone and of coordination, was administered to matched groups of children with dyslexia and control children aged 10, 14, and 18 years (55 subjects in all). The children with dyslexia showed highly significant impairments on all the cerebellar tests, and significant impairment compared even with reading age controls on 11 of the 14 tasks. Deficits on the majority of tests were among the largest found in our research program. The findings, therefore, provide further intriguing evidence of cerebellar impairment in dyslexia. We speculate that the well-established phonological deficits in dyslexia may arise initially from inefficient articulatory control attributable to cerebellar impairment.  相似文献   

9.
The study sought out to extend our knowledge regarding the origin of mathematical learning disabilities (MLD) in children by testing different hypotheses in the same samples of children. Different aspects of cognitive functions and number processing were assessed in fifth- and sixth-graders (11–13 years old) with MLD and compared to controls. The MLD group displayed weaknesses with most aspects of number processing (e.g., subitizing, symbolic number comparison, number-line estimation) and two cognitive functions (e.g., visual–spatial working memory). These findings favor the defective approximate number system (ANS) hypothesis, but do not fit well with the access deficit hypothesis. Support is also provided for the defective object-tracking system (OTS) hypothesis, the domain general cognitive deficit hypothesis and to some extent the defective numerosity-coding hypothesis. The study suggests that MLD might be caused by multiple deficits and not a single core deficit.  相似文献   

10.
Phonological processing skills and deficits in adult dyslexics   总被引：13，自引：0，他引：13  
This article presents 4 experiments aimed at defining the primary underlying phonological processing deficit(s) in adult dyslexia. 5 phonological processes, all involving spoken language, were studied: phoneme perception, phoneme awareness, lexical retrieval of phonology, articulatory speed, and phonetic coding in verbal short-term memory. 2 differently ascertained adult dyslexic groups, familial dyslexics (n = 15) and clinic dyslexics (n = 15), were the subjects in each experiment. These dyslexic groups were chosen because deficits that persist until adulthood and that are found in differently ascertained dyslexic groups are more likely to be primary. Each dyslexic group was compared to 2 control groups, chronological age (CA) controls who were similar in age and sex, and younger reading age (RA) controls who were similar in reading age and sex. The main finding was a clear deficit in phoneme awareness in both dyslexic groups, with each dyslexic group performing significantly worse than both CA and RA controls. Moreover, performance on the 2 phoneme awareness tasks together uniquely accounted for substantial variance in nonword reading. The clinic but not the familial dyslexics appeared to have an additional deficit in verbal short-term memory. No clear deficits were found in either dyslexic group in phoneme perception, lexical retrieval, or articulatory speed.  相似文献   

11.
The goals of this study were to explore the deficits in working memory associated with literacy disorders (i.e. developmental disorders of reading and/or spelling) and the developmental trajectories of these working memory deficits. The performance of 28 children with literacy disorders was compared to a non-disabled control group with the same group size at five bi-annual times of measurement in a three-year-longitudinal study beginning at the end of primary school (9.5 years of age). Storage capacity and central-executive working memory were assessed in phonological and visual-spatial modalities, the latter under static and dynamic conditions. Overall, children with literacy disorders were outperformed by their typical developing peers in all phonological and in dynamic visual-spatial storage and central-executive tasks except for the static visual-spatial storage task. Results at single times of measurement revealed that the most consistent deficit was found in the storage capacity of the phonological loop. An additional central-executive impairment is supported by low backward spans. The causes for output deficits in dynamic visual-spatial tasks and good performance under static visual-spatial condition are discussed.  相似文献   

12.
This study examined whether the characteristic reading speed impairment of German dyslexic children results from a general skill-automatization deficit sensu Nicolson and Fawcett (1990) or from more specific deficits in visual naming speed and phonological skills. The hypothesized skill-automatization deficit was assessed by balancing, peg moving, and visual search. Rapid "automatized" naming tasks served as measures of impaired visual naming speed, and the phonological deficit was assessed by speech perception, phonological sensitivity, and phonological memory tasks. Dyslexic German children and age-matched control children (all boys) were tested at the end of Grade 2 and as participants of a longitudinal study also at the beginning of Grade 1. No evidence for a skill-automatization deficit was found, as the dyslexic children did not differ at all on the balancing tasks and little on the other nonverbal skill tasks. However, the dyslexic children showed impaired visual naming speed and impaired phonological memory performance that were observed not only in Grade 2 but also before learning to read. Overall, the findings support the conclusion that, even in regular orthographies, difficulties in learning to read are due to a phonological deficit and not to a general skill-automatization deficit.  相似文献   

13.
W E Pelham 《Child development》1979,50(4):1050-1061
Poor readers (PRs) and controls (i.e., normal readers) from the second, fourth, and sixth grades were compared on four tasks chosen to measure the development of selective attention. The PRs performed more poorly than controls on the central but not on the incidental portion of an auditory memory task. The differences on the central task were interpreted as a function of group differences in mnemonic skills rather than selective attention. There were no group differences on either central or incidental portions of a visual memory task. In a speeded classification task, PRs exhibited a slower rate of information processing, measured in bits of information transmitted per second, than controls, but this difference in rate was not affected by distraction. On a dichotic listening task, PRs performed more poorly than controls under a variety of conditions in which the presence of distraction, the rate of information presentation, and attended ear were manipulated; the pattern of differences obtained, however, was not readily interpretable as a function of greater distractibility on the part of PRs than controls. As a whole, the results did not support the hypothesis that PRs show deficits in selective attention relative to age-matched normal readers. In addition, correlations computed among indices of selectivity (residualized gain scores) derived from the four tasks were uniformly low, suggesting that the four tasks did not measure the same cognitive construct. The implications for the study of reading disabilities and for the construct of selective attention in developmental studies are discussed.  相似文献   

14.
The performance of participants with attention-deficit/hyperactivity disorder (ADHD) relative to control participants was measured on four tasks uniquely assessing the functions of selective attention, executive attention, sustained attention, and orienting of attention. The results showed that deficits in sustained attention were the most pronounced, characterizing most participants with ADHD and deficits in each of the other three functions characterized more than half of these participants. Different participants with ADHD revealed different clusters of attentional deficits. These results call for a revision of leading theories of ADHD that identify the core of the pathology as a sole deficit in executive functions.  相似文献   

15.
Few studies have looked at the strengths and weaknesses and needs of students with developmenal co‐ordination disorder (DCD). This paper describes a cohort of 93 UK students currently studying at further or higher education and who have reported motor difficulties present since childhood. The study group consisted of 21 reporting to have DCD only, 38 with DCD plus another diagnosis (a combination of any of the following: dyslexia, attention deficit hyperactivity disorder (ADHD), autism spectrum disorder (ASD), learning difficulties); 23 subjects reporting dyslexia only, and 11 students who have not been formally diagnosed. The aim of this study was to first ascertain the similarities and differences between the students in the type of support received in childhood and while at university. The second goal was to examine the reported strengths and difficulties and see how they vary for each subgroup. The DCD group reported higher levels of motor‐related difficulties such as handwriting and also executive functioning difficulties. They also had higher levels of professional support given in childhood and were also more likely to be living at home with parents compared with the dyslexia group. Despite different types of difficulties reported in the DCD group, the range of student support given across all groups was similar. Significantly more of the dyslexia group were reported to be in receipt of disability student allowance than the DCD group. The DCD and other disorders group were seen to be an intermediary group in most of the areas studied.  相似文献   

16.
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.  相似文献   

17.
The aim of this study was to compare visual and verbal memory in children with nonverbal learning disability (NLD) using the Children's Memory Scale and to identify the profile of strengths and weaknesses in visual memory abilities. Performance was significantly lower on measures of visual than verbal memory, indicating that children with NLD have deficits in visual memory despite adequate verbal memory. A unique pattern of performance emerged for the visual but not the verbal subtests. Performance on the Faces Immediate subtest was well below average, although other measures of visual memory were within the average range. Hence, it appears that children with NLD have a specific deficit on immediate memory for faces. This facial memory deficit may be linked to a deficit in right hemisphere functioning, which has already been implicated in facial processing and may also be linked with other disorders (e.g., autism spectrum disorder) in which similar facial processing deficits have been documented. More research is needed to further understand the visual memory profile of children with NLD and to inform instruction and remediation.  相似文献   

18.
A comprehensive test battery, including phonological, speed, motor and cerebellar tasks, was administered to the entire cohort of two schools for children with learning disabilities. Testing was undertaken blind without accessing the psychometric data on the children. Children were then allocated to a discrepancy group on the basis of their IQ, with the majority (n = 29) classified as nondiscrepant (IQ < 90) and a smaller set (n = 7), with IQ of at least 90, classified as discrepant (with dyslexia). Both groups showed significant deficits relative to age-matched controls on almost all the tests. On phonological, speed, and motor tasks, the nondiscrepant group were at least as severely impaired as the discrepant group. By contrast, on the cerebellar tests of postural stability and muscle tone, the nondiscrepant group performed significantly better than the children with dyslexia and close to the level of the controls. The findings indicate that cerebellar tests may prove a valuable method of differentiating between poor readers with and without IQ discrepancy. The findings are interpreted in terms of the cerebellar deficit hypothesis for dyslexia.  相似文献   

19.
Although weaknesses in metaphonological skills are well-documented in poor readers, prior studies have yielded inconsistent findings as to whether less-skilled readers also have deficits in the more primary phonological processes entailed in verbal working memory and speech production tasks. The present study was designed to examine this issue by comparing less-skilled third-graders readers (n=30) with younger children at the same reading level (n=30) and with more-skilled agemates (n=30) on a variety of tasks that require phonological processing (i.e., three “verbal memory” tasks [word span, span with concurrent processing, pseudoword imitation] and three “speech production” tasks [word-pair repetition, tongue twisters, rapid naming]). The results were striking: the less-skilled third-grade readers had significantly lower accuracy scores than both their agemates and the younger normal readers on the word span, pseudoword imitation, word-pair repetition, and tongue twister tasks. Measures of accuracy were more related to reading ability than were measures of speed. Performance on a pseudoword imitation task was the variable most strongly linked to reading achievement.  相似文献   

20.
The cognitive profiles of children with Developmental Reading Disorder (RD) and Attention-Deficit/Hyperactivity Disorders (ADHD) have been extensively studied in alphabetic language communities. Deficits in phonological processing and rapid naming have been implicated as core features of RD although whether the latter is a deficit specific to RD remains controversial. Similar research aiming to explore the cognitive profiles of children with both RD and ADHD in non-alphabetic language communities is limited. The specificity of rapid naming deficit to RD among Chinese has yet to be studied. In the first study, 43 Chinese children with confirmed diagnoses of RD + ADHD were assessed on their cognitive abilities in relating to reading. In the second study, the specificity deficit hypothesis of rapid naming to RD but not ADHD was examined. A digit naming test was administered to the RD + ADHD group (43 subjects) and an ADHD only group (49 subjects). In regard to cognitive profiling, rapid naming and orthographic knowledge were found to be the most common deficits among the Chinese RD + ADHD group. This co-morbid group was also found to have a significant deficit performance on the rapid naming task than the ADHD only group. The present findings support the double dissociation hypothesis in cognitive deficit between RD and ADHD. The results of both studies are discussed with reference to the findings of the Western counterparts.  相似文献   

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