Ability-matched Controls Research Articles

Efficacy of ABRACADABRA literacy instruction in a school setting for children with autism spectrum disorders

BackgroundThere is evidence indicating that instruction using ABRACADABRA (ABRA) – a free web application designed to promote literacy development – may benefit children with autism spectrum disorders (ASD) when administered on an individualized basis in children’s homes. AimsHere, we investigated the efficacy of ABRA instruction administered in small groups of children with ASD within a school setting. Methods and proceduresChildren were aged 5.83–8.42 years (n = 23). Some children were assigned to an instruction group and received a minimum of 20 h of ABRA instruction over 9 weeks (n = 11). The other children comprised an age- and ability-matched control group (n = 12) and received business as usual literacy instruction. Outcome measures included word-level accuracy, passage-level accuracy, and passage-level comprehension, all assessed using standardized tests that were independent of ABRA. Outcomes and resultsANOVAs comparing pre- versus post-instruction raw scores showed statistically significant improvements in word- and passage-level reading accuracy for the instruction group relative to the control group, with large effect sizes. Gains in reading comprehension for the instruction group were not statistically significant and, in a posthoc correlational analysis, appeared to be related to children’s socialisation skills (r = .62). Conclusions and implicationsLiteracy instruction using ABRA is associated with improvement in reading accuracy for children with ASD when administered in small groups within a school setting. Children with ASD may require additional supports to make gains in reading comprehension when literacy instruction using ABRA is delivered in groups.

Autism is associated with reduced ability to interpret grasping actions of others

We investigated the ability of children with ASD to discriminate a small cylinder from a large cube by observing a point-light movie of an actor grasping the object, either from an allocentric or egocentric viewpoint (observing action of others or self). Compared with typically developing controls, high functioning autistic children showed a strong selective impairment in this task, but only with the allocentric viewpoint, where thresholds were twice as high: egocentric thresholds were similar to age- and ability-matched controls. The magnitude of the impairment correlated strongly with the degree of symptomology (R2 = 0.5). The results suggest that children with ASD might be impaired in their ability to predict and infer the consequences of others’ movements, which could be related to the social-communicative deficits often reported in autism.

Further understanding of complex information processing in verbal adolescents and adults with autism spectrum disorders.

More than 20 years ago, Minshew and colleagues proposed the Complex Information Processing model of autism in which the impairment is characterized as a generalized deficit involving multiple modalities and cognitive domains that depend on distributed cortical systems responsible for higher order abilities. Subsequent behavioral work revealed a related dissociation between concept formation and concept identification in autism suggesting the lack of an underlying organizational structure to manage increases in processing loads. The results of a recent study supported the impact of this relative weakness in conceptual reasoning on adaptive functioning in children and adults with autism. In this study, we provide further evidence of the difficulty relatively able older adolescents and adults with autism have with conceptual reasoning and provide evidence that this characterizes their difference from age- and ability-matched controls with typical development better than their differences in language. For verbal adults with autism, language may serve as a bootstrap or compensatory mechanism for learning but cannot overcome an inherent weakness in concept formation that makes information processing challenging as task demands increase.

Prospective memory in adults with high-functioning autism spectrum disorders: exploring effects of implementation intentions and retrospective memory load.

This study examined, for the first time, the impact of implementation intentions on prospective memory (PM) performance in adults with autism spectrum disorders (ASD) and further explored the role of retrospective memory for PM in ASD. PM was assessed with Virtual Week, a computerized game simulating upcoming everyday-life tasks. Twenty-seven adults with ASD and 27 age- and ability-matched controls were included. Half of the participants were instructed to form implementation intentions (i.e., encoding PM tasks in form of if-then statements), while the rest received simple PM instructions. Results provide first tentative evidence for beneficial effects of implementation intentions and PM tasks with low demands on retrospective memory for adults with ASD's PM. Overall, results point to the importance of planning and retrospective memory for successful prospective remembering in ASD.

Development of magnitude processing in children with developmental dyscalculia: space, time, and number.

Developmental dyscalculia (DD) is a learning disorder associated with impairments in a preverbal non-symbolic approximate number system (ANS) pertaining to areas in and around the intraparietal sulcus (IPS). The current study sought to enhance our understanding of the developmental trajectory of the ANS and symbolic number processing skills, thereby getting insight into whether a deficit in the ANS precedes or is preceded by impaired symbolic and exact number processing. Recent work has also suggested that humans are endowed with a shared magnitude system (beyond the number domain) in the brain. We therefore investigated whether children with DD demonstrated a general magnitude deficit, stemming from the proposed magnitude system, rather than a specific one limited to numerical quantity. Fourth graders with DD were compared to age-matched controls and a group of ability-matched second graders, on a range of magnitude processing tasks pertaining to space, time, and number. Children with DD displayed difficulties across all magnitude dimensions compared to age-matched peers and showed impaired ANS acuity compared to the younger, ability-matched control group, while exhibiting intact symbolic number processing. We conclude that (1) children with DD suffer from a general magnitude-processing deficit, (2) a shared magnitude system likely exists, and (3) a symbolic number-processing deficit in DD tends to be preceded by an ANS deficit.

Impact of inhibitory load on remembering delayed intentions in autism

Objective:Research on prospective memory (PM) in autism spectrum disorders (ASD) is scarce and inconsistent. Differences in results have been attributed to differences in executive control demands of the respective PM tasks. However, so far no study has systematically and experimentally manipulated executive control load. The present study set out to explore the impact of varying inhibitory control demands on PM performance in ASD.Method:Twenty-two adults with ASD and 22 age-, gender- and cognitive ability-matched controls were asked to work on a computerised word categorization task into which an event-based PM task was embedded. In addition, they were required to work on a task that put either low or high load on inhibitory resources.Results:With regards to the event-based PM task, no significant effects emerged. Controls outperformed individuals with ASD on the ongoing task performance and ongoing task performance varied with inhibition load. Similarly, inhibition load affected performance on the inhibition task; here, no group effects were found.Conclusion:Findings suggest spared event-based PM performance in ASD regardless of inhibition load. However, results might be limited by ceiling effects and future studies are needed to investigate to explore inhibition effects using more difficult tasks.

Do Adults with Autism Spectrum Disorders Compensate in Naturalistic Prospective Memory Tasks?

The present study is the first to directly compare event- and time-based prospective memory in Autism Spectrum Disorders (ASD) using a contextual task mirroring real life demands of prospective memory. Twenty-five individuals with ASD and 25 age- and ability-matched controls completed the Dresden Breakfast task which required participants to prepare breakfast following a set ofrules and time restrictions. Overall, adults with ASD had less correct time- and event-based prospective memory responses in comparison to controls, which is consistent with previous research in children with ASD. Moreover, ASD participants completed fewer tasks, followed rules less closely, and monitored the elapsing time less closely than controls. Individuals with ASD seem not to be compensating in naturalistic prospective memory tasks.

Memory in autistic spectrum disorder.

Behavioral evidence concerning memory in forms of high-functioning autism (HFA) and in moderately low-functioning autism (M-LFA) is reviewed and compared. Findings on M-LFA are sparse. However, it is provisionally concluded that memory profiles in HFA and M-LFA (relative to ability-matched controls) are similar but that declarative memory impairments are more extensive in M-LFA than in HFA. Specifically, both groups have diminished memory for emotion- or person-related stimuli. Regarding memory for nonsocial stimuli, both groups probably have mental-age-appropriate nondeclarative memory, and within declarative memory, both groups have mental-age-appropriate immediate free recall of within-span or supraspan lists of unrelated items, as well as cued recall and paired associate learning. By contrast, recognition is largely unimpaired in HFA but moderately impaired in M-LFA, and free recall of meaningful or structured stimuli is moderately impaired in HFA but more severely impaired in M-LFA. Theoretical explanations of data on declarative memory in HFA identify problems in the integrative processing, or the consolidation and storage, of complex stimuli or a specific problem of recollection. Proposed neural substrates include the following: disconnectivity of primary sensory and association areas; dysfunctions of medial prefrontal cortex, hippocampus, or posterior parietal lobe; or combinations of these associated with neural disconnectivity. Hypothetically, perirhinal dysfunction might explain the more extensive declarative memory impairments in M-LFA. Foreseeable consequences of uneven memory abilities in HFA and M-LFA are outlined, including possible effects on language and learning in M-LFA. Finally, priorities for future research are identified, highlighting the urgent need for research on memory in lower functioning individuals.

Numerical magnitude processing in children with mild intellectual disabilities

The present study investigated numerical magnitude processing in children with mild intellectual disabilities (MID) and examined whether these children have difficulties in the ability to represent numerical magnitudes and/or difficulties in the ability to access numerical magnitudes from formal symbols. We compared the performance of 26 children with MID on a symbolic (digits) and a non-symbolic (dot-arrays) comparison task with the performance of two control groups of typically developing children: one group matched on chronological age and one group matched on mathematical ability level. Findings revealed that children with MID performed more poorly than their typically developing chronological age-matched peers on both the symbolic and non-symbolic comparison tasks, while their performance did not substantially differ from the ability-matched control group. These findings suggest that the development of numerical magnitude representation in children with MID is marked by a delay. This performance pattern was observed for both symbolic and non-symbolic comparison tasks, although difficulties on the former task were more prominent. Interventions in children with MID should therefore foster both the development of magnitude representations and the connections between symbols and the magnitudes they represent.

Reading development and dyslexia in a transparent orthography: a survey of Spanish children

Spanish-speaking children learn to read words printed in a relatively transparent orthography. Variation in orthographic transparency may shape the architecture of the reading system and also the manifestation of reading difficulties. We tested normally developing children and children diagnosed with reading difficulties. Reading accuracy was high across experimental conditions. However, dyslexic children read more slowly than chronological age (CA)-matched controls, although, importantly, their reading times did not differ from those for ability-matched controls. Reading times were significantly affected by frequency, orthographic neighbourhood size and word length. We also found a number of significant interaction effects. The effect of length was significantly modulated by reading ability, frequency and neighbourhood. Our findings suggest that the reading development of dyslexic children in Spanish is delayed rather than deviant. From an early age, the salient characteristic of reading development is reading speed, and the latter is influenced by specific knowledge about words.

Abnormal Adaptive Face-Coding Mechanisms in Children with Autism Spectrum Disorder

In low-level vision, exquisite sensitivity to variation in luminance is achieved by adaptive mechanisms that adjust neural sensitivity to the prevailing luminance level. In high-level vision, adaptive mechanisms contribute to our remarkable ability to distinguish thousands of similar faces [1]. A clear example of this sort of adaptive coding is the face-identity aftereffect [2, 3, 4, 5], in which adaptation to a particular face biases perception toward the opposite identity. Here we investigated face adaptation in children with autism spectrum disorder (ASD) by asking them to discriminate between two face identities, with and without prior adaptation to opposite-identity faces. The ASD group discriminated the identities with the same precision as did the age- and ability-matched control group, showing that face identification per se was unimpaired. However, children with ASD showed significantly less adaptation than did their typical peers, with the amount of adaptation correlating significantly with current symptomatology, and face aftereffects of children with elevated symptoms only one third those of controls. These results show that although children with ASD can learn a simple discrimination between two identities, adaptive face-coding mechanisms are severely compromised, offering a new explanation for previously reported face-perception difficulties [6, 7, 8] and possibly for some of the core social deficits in ASD [9, 10].

Temporal Cognition in Children with Autistic Spectrum Disorders: Tests of Diachronic Thinking

Impaired diachronic thinking-(the propensity and capacity to think about events spreading across time)-was demonstrated in a 2-Phase study in which children with autism were compared with age and ability matched controls. Identical tests of diachronic thinking were administered in both phases of the study, but to different participant groups, with the same results. The marked impairments shown are therefore robust. Various non-temporal explanations of the findings were eliminated by the results of control tasks in Phase 2. Diachronic thinking did not correlate with verbal or non-verbal ability, age, or mentalising ability, consistent with other evidence of the specificity of diachronic thinking ability. Possible causes of impaired diachronic thinking in autism are discussed.

Perceptual Similarity in Autism

People with autism have consistently been found to outperform controls on visuo-spatial tasks such as block design, embedded figures, and visual search tasks. Plaisted, O'Riordan, and others (Bonnel et al., 2003; O'Riordan & Plaisted, 2001; O'Riordan, Plaisted, Driver, & Baron-Cohen, 2001; Plaisted, O'Riordan, & Baron-Cohen, 1998a, 1998b) have suggested that these findings might be explained in terms of reduced perceptual similarity in autism, and that reduced perceptual similarity could also account for the difficulties that people with autism have in making generalizations to novel situations. In this study, high-functioning adults with autism and ability-matched controls performed a low-level categorization task designed to examine perceptual similarity. Results were analysed using standard statistical techniques and modelled using a quantitative model of categorization. This analysis revealed that participants with autism required reliably longer to learn the category structure than did the control group but, contrary to the predictions of the reduced perceptual similarity hypothesis, no evidence was found of more accurate performance by the participants with autism during the generalization stage. Our results suggest that when all participants are attending to the same attributes of an object in the visual domain, people with autism will not display signs of enhanced perceptual similarity.

Inner speech impairments in autism

Three experiments investigated the role of inner speech deficit in cognitive performances of children with autism. Experiment 1 compared children with autism with ability-matched controls on a verbal recall task presenting pictures and words. Experiment 2 used pictures for which the typical names were either single syllable or multisyllable. Two encoding conditions manipulated the use of verbal encoding. Experiment 3 employed a task-switching paradigm for which performance has been shown to be contingent upon inner speech. In Experiment 1, children with autism demonstrated a lower picture-superiority effect compared to controls. In Experiment 2, the children with autism showed a lower word-length effect when pictures were presented alone, but a more substantial word-length effect in a condition requiring overt labelling. In Experiment 3, articulatory suppression affected the task-switching performance of the control participants only. Individuals with autism have limitations in their use of inner speech.

Paradoxical autonomic response to mental tasks in autism.

Autonomic responses to mental tasks requiring sustained attention were examined in individuals with autism and age- and ability-matched controls. Cardiac autonomic function (CAF) was evaluated based on heart rate variability. While the control group showed a significant decrease in the parasympathetic function during mental tasks, the autistic group showed no significant changes in CAF. When examined individually, parasympathetic function was suppressed in all subjects in the control group. On the other hand, parasympathetic function was activated in half of the autistic subjects. The paradoxical autonomic response suggests that some autistic subjects were more stressed under 'resting' conditions than while performing mechanical or repetitive mental tasks. The results seem to support autonomic hyperarousal in some people with autism.

Long-term memory and levels-of-processing in autism

Prior studies reported that long-term memory (LTM) was basically unimpaired in individuals with autism. However, people with autism have been found to perform worse than ability-matched controls when verbal materials to be remembered are semantically related. In normal subjects, semantic processing of verbal materials facilitates LTM better than ‘shallow’ (phonological or perceptual) processing, which is known as the levels-of-processing effect. In this study, the relationship between LTM and semantic processing was investigated using a levels-of-processing task. In Study 1, a levels-of-processing task was conducted on healthy volunteers, which confirmed the levels-of-processing effect with our task. In study 2, the same task was conducted on autistic subjects with mild or no mental retardation and ability-matched controls. The levels-of-processing effect was confirmed in the control group. Although overall performance in the two groups was comparable, the levels-of-processing effect was not found in the autistic group. LTM resulting from perceptual processing was better in the autistic group than in the control group, indicating superior ‘rote memory’ in individuals with autism. Furthermore, the pattern of correlations between LTM performance and cognitive measures differed greatly between the two groups. The lack of the levels-of-processing effect, which has not been reported in other psychiatric or neuropathological conditions, suggests an abnormal relationship between semantic memory and episodic memory in individuals with autism.

Working Memory Impairments in Children with Specific Arithmetic Learning Difficulties

Working memory impairments in children with difficulties in arithmetic have previously been investigated using questionable selection techniques and control groups, leading to problems concluding where deficits may occur. The present study attempted to overcome these criticisms by assessing 9-year-old children with difficulties specific to arithmetic, as indicated by normal reading, and comparing them with both age-matched and ability-matched controls. A battery of 10 tasks was used to assess different aspects of working memory, including subtypes of executive function. Relative to age-matched controls, children with poor arithmetic had normal phonological working memory but were impaired on spatial working memory and some aspects of executive processing. Compared to ability-matched controls, they were impaired only on one task designed to assess executive processes for holding and manipulating information in long-term memory. These deficits in executive and spatial aspects of working memory seem likely to be important factors in poor arithmetical attainment.

Evidence for executive dysfunction in autism

A group of young people with autism (ranging in ability from high functioning to moderately learning disabled), and ability-matched control groups of (i) non-autistic individuals with moderate learning disabilities, and (ii) normally developing children, were presented with two tests of executive function: the Intra-dimensional/Extra-dimensional set-shifting task and the Tower of London planning task. These tests were graded in difficulty and included internal control measures. On each task, the autistic group was differentially impaired with respect to both control groups. Moreover, this impairment was specific to the stages of each task which placed greatest demands upon executive control. This evidence for executive dysfunction in autism is discussed in the context of Norman and Shallice's ( Centre for Human Information Processing Technical Report 99, 1980) “Supervisory Attentional System” model of frontal function.

The Triple X Chromosome Syndrome in Childhood: Recent Empirical Findings

This study addresses the issue of the relationship between intellectual ability and the X chromosome. It involves a sample of 11 girls ranging in age from 8 to 11 years who were identified at birth as having an extra X chromosome through a screening program for sex chromosome abnormalities. The purpose was to examine their performance on verbal, nonverbal, and memory tasks. The first study compared triple X girls with their normal siblings on standardized ability tasks. The results revealed markedly lower verbal skills in the extra X girls as well as a short-term memory deficit for sequentially ordered auditory information. The second study compared triple X subjects to age-matched normal girls on laboratory-based tasks of verbal and spatial information processing. The results revealed greater impairments with the verbal than the spatial task. The third study, which dealt with their recall abilities, involved comparing triple X girls with age- and ability-matched female controls on a wide variety of short-term memory tasks. The results showed that the triple X girls were markedly inferior in their performance on these tasks, indicating a rehearsal deficit, an inability to use list structures, and weaker language skills. The results are discussed in terms of the influence of various biological factors in mediating the deficits observed.

Memory for recent events in autistic children.

An experiment is reported in which autistic children's memory for recent events was compared with that of normal age-matched and retarded age-and ability-matched controls. The autistic subjects' recall was significantly inferior to that of normal controls. Recent event memory correlated with a language measure in the autistic group and with a nonverbal measure in the retarded control group. These findings are discussed in terms of relationships between language and memory, and possible mechanisms underlying the distinctive pattern of memory ability and disability that occurs in autism.