The intellectual profile of children with autism spectrum disorders may be underestimated: A comparison between two different batteries in an Italian sample.

Intelligence measures are typically used in the assessment of children with autism spectrum disorders (ASD), but there is a paucity of research on the implications of such testing. In the present study, we examined children with ASD using two of the most largely adopted instruments, i.e., the WISC-IV, arguably the most utilized scale in the world; and the Leiter-3, a nonverbal scale that also excludes, from the IQ calculation, working memory and processing speed, which are points of weakness in ASD. Results showed that IQ and indices of these two batteries are strongly correlated. However, the WISC-IV IQ might underestimates the potential of children with ASD, particularly in children with a low functioning profile. These hold true for both the full scale IQ and three out of four indices of the WISC-IV, with remarkable implications for both assessment and treatment of these children. Practitioners working with children with ASD should be aware that the battery that they are using might severely affect the estimation of these children's potential.

Using Z and age-equivalent scores to address WISC-IV floor effects for children with intellectual disability.

BACKGROUND: The Wechsler Intelligence Scale for Children - Fourth Edition often produces floor effects in individuals with intellectual disability. Calculating respondents' Z or age-equivalent scores has been claimed to remedy this problem. METHOD: The present study applied these methods to the Wechsler Intelligence Scale for Children - Fourth Edition scores of 198 individuals diagnosed with intellectual disability. Confirmatory factor analysis and profile analysis were conducted using a Bayesian approach. RESULTS: The intelligence structure in intellectual disability resembled the one previously reported for typical development, suggesting configural but not metric invariance. When Z or age-equivalent scores (but not traditional scaled scores) were used, the average profile resembled the one previously reported for other neurodevelopmental disorders. CONCLUSIONS: Both methods avoided any floor effects, generating similar but not identical profiles. Despite some practical and conceptual limitations, age-equivalent scores may be easier to interpret. This was true even for a subgroup of individuals with more severe disabilities (mean IQ < 43).

Difficulties in working memory updating in individuals with intellectual disability.

BACKGROUND: Despite the critical role attributed to working memory (WM) updating for executive functions and fluid intelligence, no research has yet been carried out on its specific role in the vital case of fluid intelligence weakness, represented by individuals with intellectual disability (ID). Furthermore, the relationship between updating and other WM functions has not been considered in depth. METHOD: The current study examines these areas by proposing a battery of WM tasks (varying in degree of active attentional control requested) and one updating task to groups of ID individuals and typically developing children, matched for fluid intelligence performance. RESULTS: Comparison between the group of ID individuals and a group of children showed that, despite being matched on the Raven test, the updating measure significantly differentiated the groups as well as the WM complex span. Furthermore, updating proved to be the task with the greatest power in discriminating between groups. CONCLUSIONS: Our results confirm the importance of the demand for active attentional control in explaining the role of WM in fluid intelligence performance, and in particular show that updating information in WM plays an important role in the distinction between typically developing children and ID individuals.

A specific deficit in visuospatial simultaneous working memory in Down syndrome.

BACKGROUND: Recent studies have demonstrated that individuals with Down syndrome (DS) present both central and verbal working memory deficits compared with controls matched for mental age, whereas evidence on visuospatial working memory (VSWM) has remained ambiguous. The present paper uses a battery of VSWM tasks to test the hypothesis that individuals with DS can also encounter specific difficulties in VSWM. METHOD: Four tasks were administered to 34 children and adolescents with DS and 34 controls matched for verbal mental age. In two of these tasks, participants had to remember a series of locations sequentially presented on a matrix (spatial-sequential WM); in another two, they had to remember locations simultaneously presented (spatial-simultaneous WM). RESULTS AND CONCLUSIONS: Results showed that individuals with DS are poorer than controls in the spatial-simultaneous tasks, but not in the spatial-sequential tasks. These findings were not due to a difference in speed of visuospatial processing. In fact, when performances of the two groups in VSWM were compared using speed measures as covariates, differences between groups remained. It is suggested that the simultaneous VSWM deficit of individuals with DS could be due to the request for processing more than one item at a time.

Visuospatial working memory in Turner's syndrome.

Turner's syndrome is a genetic disorder, specific to women, in which one of the X chromosomes is partially or completely deleted. This syndrome is associated with physical features such as short stature or failure in primary and secondary sexual development, together with a specific pattern of cognitive functions. It has been suggested that women affected by Turner's syndrome perform poorly in tasks measuring visuospatial abilities and have a verbal IQ significantly higher than performance IQ. Although this result has received strong empirical support, the nature of the visuospatial deficit is still unclear. Recent studies on visuospatial processes have highlighted that the underlying cognitive structure is more complex than previously suggested and several dissociations have been reported (e.g., visual vs spatial, sequential vs simultaneous, or passive vs active processes). In the present study we analyze in detail the characteristics of the visuospatial deficit associated with Turner's syndrome by presenting four young women with a comprehensive battery of tasks designed to tap all aspects of visuospatial working memory. Results confirm that Turner's syndrome is associated with a general visuospatial working memory deficit, but the pattern of performance of different cases can be different, with a greater emphasis on active visuospatial processes. and on either sequential or simultaneous spatial processes.

Working memory and updating processes in reading comprehension.

In this study, we examine the relation between reading comprehension ability and success in working memory updating tasks. Groups of poor and good comprehenders, matched for logical reasoning ability, but different in reading comprehension ability, were administered various updating tasks in a series of experiments. In the first experiment, the participants were presented with lists of words, the length of which (4-10 words) was unknown beforehand, and were required to remember the last 4 words in each series. In this task, we found a decrease in performance that was related to longer series and poor reading ability. In the second experiment, we presented lists of nouns referring to items of different sizes, in a task that simulated the selection and updating of relevant information that occurs in the on-line comprehension process. The participants were required to remember a limited, predefined number of the smallest items presented. We found that poor comprehenders not only had a poorer memory, but also made a greater number of intrusion errors. In the third and fourth experiments, memory load (number of items to be selected) and suppression request (number of potentially relevant items) were manipulated within subjects. Increases in both memory load and suppression requests impaired performance. Furthermore, we found that poor comprehenders produced a greater number of intrusion errors, particularly when the suppression request was increased. Finally, in a fifth experiment, a request to specify the size of presented items was introduced. Poor comprehenders were able to select the appropriate items, although their recall was poorer. Altogether, the data show that working memory abilities, based on selecting and updating relevant information and avoiding intrusion errors, are related to reading comprehension.

Working memory interference control deficit in children referred by teachers for ADHD symptoms.

It has been hypothesised that children with Attention Deficit/Hyperactivity Disorder (ADHD) present memory problems, including working memory deficits. This research is aimed at finding clearer evidence of a working memory deficit in these children. In the first study 22 children that had been referred by teachers as having ADHD symptoms were compared with a control group. Their performance on a listening span test, drawn up by De Beni, Palladino, Pazzaglia, and Cornoldi (1998), was investigated. In this task the subjects were asked to select the names of animals in word strings and to remember the last word in each string. In a second study, 34 children with ADHD symptoms and 50 control children were presented with a visuospatial working memory task mirroring the verbal task used in Study 1. In both studies, the children with ADHD symptoms had difficulty in remembering the last item in the string and had a higher number of intrusions when memorising items that were not in the final position. The results were interpreted that children with ADHD symptoms have working memory problems because they are not capable of suppressing information that initially has to be processed, and subsequently excluded from memory. This particular difficulty can be interpreted as an inhibitory processing deficit. The implications of the results in understanding learning difficulties in children with ADHD are discussed.

Passive and active processes in visuo-spatial memory: double dissociation in developmental learning disabilities.

The distinction between passive and active visuo-spatial memory has been useful to interpret various pattern of deficits reported in individual differences studies. However, this interpretation raises the issue of task difficulty, since active tasks could be failed simply because more complex and the corresponding deficit could reflect a reduced capacity of the system. We describe two children with Nonverbal Learning Disability whose performance provides evidence of a dissociation between passive and active memory processes. One of the children showed a selective impairment in passive tasks and performed flawlessly in active tasks, whereas the second child displayed the opposite pattern. These data suggest that a qualitative difference between passive and active processes does exist and that differences in performance do not reflect a lower/higher level of task difficulty. Further, these data underlie the importance of formulating theoretical models of visuo-spatial memory including both material-related (i.e., visual vs spatial) and process-related (i.e., passive vs active) distinctions.

Working memory and intrusions of irrelevant information in a group of specific poor problem solvers.

An important body of evidence has shown that reading comprehension ability is related to working memory and, in particular, to the success in Daneman and Carpenter's (1980) reading and listening span test. This research tested a similar hypothesis for arithmetic word problems, since, in order to maintain and process the information, they require working memory processes. A group of children possessing average vocabulary but poor arithmetic problem-solving skills was compared with a group of good problem solvers, matched for vocabulary, age, and socioeconomic status. Poor problem solvers presented lower recall and a greater number of intrusion errors in a series of tasks testing working memory and memory for problems. The results obtained over a series of six experimental phases, conducted during a 2-school-year period, offer evidence in favor of the hypotheses that groups of poor problem solvers may have poor performance in a working memory test requiring inhibition of irrelevant information (Hypothesis 1), but not in other short-term memory tests (Hypothesis 2), that this difficulty is related to poor recall of critical information and greater recall of to-be-inhibited information (Hypothesis 3), that poor problem solvers also have difficulty in remembering only relevant information included in arithmetic word problems (Hypothesis 4) despite the fact that they are able to identify relevant information (Hypothesis 5). The results show that problem-solving ability is related to the ability of reducing the memory accessibility of nontarget and irrelevant information.

The role of distinct components of visuo-spatial working memory in the processing of texts.

Three experiments examined whether visuo-spatial working memory is involved in processing spatial descriptions and tested whether different processes within the visuo-spatial working memory are involved in processing different kinds of descriptions. Experiment 1 considered the performance of two groups with low and high visuo-spatial working memory abilities in memorizing the description of a city. The high visuo-spatial working memory group had a better memory performance than the low visuo-spatial working memory group. In Experiment 2, the Brooks' (1967) task was adapted to investigate the selective interference of four different concurrent tasks (a verbal, a visual, a spatial-sequential, and a spatial-simultaneous task) on the recall of short abstract, visual and spatial texts. In Experiment 3, the same distinction was extended to longer and natural descriptions of different environments. Participants listened to three descriptions: a description that mainly stressed the visual properties of an environment, a description from a route perspective, and a description from a survey perspective. They also performed the concurrent visual and the two concurrent spatial tasks proposed in Experiment 2. Results of Experiments 2 and 3 demonstrated that tasks involving different cognitive resources (i.e. the verbal, visual, spatial-simultaneous, and the spatial-sequential tasks) had a differential interference with the free recall of different kinds of descriptions.

Imagery deficits in nonverbal learning disabilities.

This study reports the observations gathered from 11 children referred to consulting services because of learning difficulties at school and diagnosed with nonverbal learning disabilities (NVLD). These children had an average verbal IQ, but a WISC-R performance IQ lower than the verbal IQ by at least 15 points and experienced difficulties especially in mathematics and drawing. The children completed a battery of four tasks requiring visuospatial working memory and visual imagery: a memory task composed of pictures and their positions (Pictures task), a task that required them to memorize the positions filled in a matrix (Passive Matrix task), a task that required them to imagine a pathway along a matrix (Active Matrix task) and a task that required them to learn groups made up of three words, using a visual interactive imagery strategy (TV task). In comparison to a control group of 49 children, children with NVLD scored lower in all the tasks, showing deficits in the use of visuospatial working memory and visual imagery. By contrasting subgroups of children of different ages in the control group, it was possible to show that some tasks did not show a clear developmental trend. Thus the deficits shown by the children with NVLD cannot simply be attributed to a developmental delay of these children, but seem to reflect a more severe disability.

Increases in intrusion errors and working memory deficit of poor comprehenders.

This study tests the hypothesis that the ability to inhibit already processed and actually irrelevant information could influence performance in the listening span test (Daneman & Carpenter, 1980) and have a crucial role in reading comprehension. In two experiments, the listening span test and a new working memory test were given to two groups of young adults, poor and good comprehenders, matched for logical reasoning ability. In Experiment 1, the poor comprehenders had a significantly lower performance in the listening span test associated to a higher number of intrusions--that is, recalled words that, in spite of being in sentence form, were not placed in the last position. In Experiment 2, a new working memory test was devised in order to analyse more effectively the occurrence of intrusions. Subjects were required to listen to a growing series of strings of animal and non-animal words. While listening, they had to detect when an animal word occurred, and at the end of each series they had to recall the last word of each string. The poor comprehenders obtained a significantly lower performance in the memory task and made a higher number of intrusions, particularly of animal words.

Visuo-spatial working memory: structures and variables affecting a capacity measure.

The present paper examines the issue of the capacity of visuo-spatial working memory. A series of experiments test the hypothesis that two different components are critical in visuo-spatial working memory (passive store and active imagery operations), and, thereafter, attempt to specify the variables that affect the capacity of the passive store component. In the experiments, congenitally blind and sighted participants were asked to remember the spatial positions of target objects in two-dimensional matrices, with or without simultaneously performing a sequence of spatially-based imagery operations. We considered both the positions recall performance (the passive storage component) and the sequential imagery processing performance (the active processing component). We suggest that the two components of visuo-spatial working memory are independent. We also propose that both the number of relevant matrices and the number of target objects within each matrix affect the capacity of visuo-spatial working memory, with the latter factor possibly playing a greater role than the former one.

Visuo-spatial working memory limitations in low visuo-spatial high verbal intelligence children.

Visuo-spatial working memory was investigated in a group of 37 children aged between 10 and 14 years with low visuo-spatial intelligence. Their performance was poorer than that of a matched control group on a series of tests devised to ascertain visuo-spatial working memory yet was broadly similar in a language test and in school achievement tests. It is argued that low visuo-spatial intelligence children typically present limitations in the storage capacity of a passive system of the visuo-spatial working memory (with a raw measure of four-five stored elements) and especially in the operations required to process that information.

Do you remember what you imagined you would do in that place? The motor encoding cue-failure effect in sighted and blind people.

Three experiments examine why the recall of performed actions often fails to profit from provision of retrieval context. A cue failure has, for instance, been demonstrated with cued recall for performed actions in that cued recall is lower than free recall, whereas control conditions show the usual free to cued recall increase for non-enacted material. The first experiment confirms the cue-failure effect and extends the generality of the finding to everyday cue contexts (where the cues are represented by images of the locations associated to the actions), which intuitively should be of general retrieval help. The second experiment shows that the cue-failure effect is also present, even to a greater extent, in congenitally totally blind people; the third experiment suggests how the cue-failure effect may be defeated by means of simultaneous motor and non-motor encoding. The results are discussed in terms of strategic and non-strategic conceptions of action memory and of the independence of motor and visuospatial codes. This independence appears maintained also in the blind.

Why are there sometimes concreteness effects in memory for prose?

Four experiments explored on-line encoding strategies and memory for high imagery and low imagery texts. Results consistently indicated that concreteness effects in memory for text depend on how materials are presented in several different respects. Most importantly, the experiments clarified apparently contradictory results of previous studies by indicating that concreteness effects generally do not occur in memory for prose when imageability is manipulated between-subjects, and that their occurrence when imageability is manipulated within-subjects depends on the order occurrence when imageability is manipulated within-subjects depends on the order of presentation. In addition, moving window analyses of text processing strategies indicated that differential strategies observed in previous studies when subjects listened to high vs low imagery text do not generalize to reading of the same materials. Potential explanations for the pattern of results are evaluated, and implications for theories of mental imagery and memory are considered.

Processing capacity limitations in pictorial and spatial representations in the totally congenitally blind.

The study of visuo-spatial imagery abilities in totally congenitally blind people may be instrumental in understanding the contribution of visual experience to imagery processes. In the present paper visuo-spatial imagery capacity was explored through a task devised by Kerr (1987) and adapted for presentation to the blind, in which subjects were asked to imagine either two- or three-dimensional matrices of different complexity and to follow a mental pathway. The first experiment showed that blind people have difficulty with three-dimensional matrices which are within the reach of sighted people, and that their performance is affected by the processing rate. In the second experiment the spatial and pictorial components of visual imagery were analyzed by way of the same spatial task and of a pictorial-tactual task in which subjects had to match a mental representation of a pathway to a tactually explored wire silhouette. On the latter task, blind people did not meet any particular difficulty, probably because they could form representations using other sensory modalities and because they were skillful in tactual exploration. These data suggest that research on the blind cannot easily contribute to the distinction between the spatial and pictorial components of visual imagery.

Deaf and hard of hearing adolescents' memory for concrete and abstract prose. Effects of relational and distinctive information.

In two experiments, we examined deaf and hard of hearing adolescents' memory for prose as compared to that of hearing students. The study focused on the possibility that deaf and hard of hearing readers might make relatively less use of relational information in textual materials. Text structure and material concreteness were manipulated, and memory for relational and distinctive information was assessed. Results indicated that deaf and hard of hearing students remembered the abstract materials as well as they did the concrete materials. They were less likely than hearing students to remember idea units (concrete or abstract) holistically within passages, but they showed relatively better memory for individual words. This difference disappeared when the same sentences were presented without global paragraph coherence. The findings suggest that deaf and hard of hearing readers may be less likely than hearing readers to integrate text information across idea units, although they may retain as much information from within units.

Bizarreness effect in dream recall.

This study aimed to ascertain a) whether morning reports of dream experience more frequently reproduce bizarre contents of night reports than nonbizarre ones and b) whether this effect depends on the rarity of bizarre contents in the dream or on their richer encoding in memory. Ten subjects were awakened in rapid eye movement (REM) sleep three times per night for 4 nonconsecutive nights and asked to report their previous dream experiences. In the morning they were asked to re-report those dreams. Two separate pairs of judges scored the reports: the former identified the parts in each report with bizarre events, characters or feelings and the latter parsed each report into content units using transformational grammar criteria. By combining the data of the two analyses, content units were classified as bizarre or nonbizarre and, according to whether present in both the night and corresponding morning reports, as semantically equivalent or nonequivalent. The proportion of bizarre contents common to night and morning reports was about twice that of nonbizarre contents and was positively correlated to the quantity of bizarre contents present in the night report. These findings support the view that bizarreness enhances recall of dream contents and that this memory advantage is determined by a richer encoding at the moment of dream generation. Such a view would seem to explain why dreams in everyday life, which are typically remembered after a rather long interval, appear more markedly bizarre than those recalled in the sleep laboratory.