Spatial exploration and navigation in Down syndrome and Williams syndrome.

We know little about the ability to explore and navigate large-scale space for people with intellectual disability (ID). In this cross-syndrome study, individuals with Down syndrome (DS), individuals with Williams syndrome (WS) and typically developing children (TD; aged 5-11 years) explored virtual environments with the goal of learning where everything was within the environment (Experiment 1) or to find six stars (Experiment 2). There was little difference between the WS and DS groups when the goal was simply to learn about the environment with no specific destination to be reached (Experiment 1); both groups performed at a level akin to a subset of TD children of a similar level of non-verbal ability. The difference became evident when the goal of the task was to locate targets in the environment (Experiment 2). The DS group showed the weakest performance, performing at or below the level of a subset of TD children at a similar level of non-verbal ability, whilst the WS group performed at the level of the TD subset group. The DS, WS and TD group also demonstrated different patterns of exploration behavior. Exploration behaviour in DS was weak and did not improve across trials. In WS, exploration behavior changed across trials but was atypical (the number of revisits increased with repeated trials). Moreover, transdiagnostic individual difference analysis (Latent Profile Analysis) revealed five profiles of exploration and navigation variables, none of which were uniquely specific to DS or to WS. Only the most extreme profile of very poor navigators was specific to participants with DS and WS. Interestingly, all other profiles contained at least one individual with DS and at least one individual with WS. This highlights the importance of investigating heterogeneity in the performance of individuals with intellectual disability and the usefulness of a data-driven transdiagnostic approach to identifying behavioral profiles.

The French Version of the DABS: Adaptation Process and Preliminary Field Test.

The aim of this study was to develop a transcultural adaptation of the Diagnostic Adaptive Behavior Scale (DABS) in French and to perform a field evaluation of the adapted version of the tool (DABS-F). Eight experts in intellectual and developmental disabilities (IDD) and two professional translators formed two committees to translate the instrument. Thirty-four independent experts in IDD rated the clarity and relevance of the DABS-F. Results indicated complete agreement between the two translation committees and also demonstrated very satisfactory levels of clarity and relevance for the DABS-F. The latter result can be considered as evidence of the content validity of the adapted tool. Adjustments for the few items that presented less satisfactory results are discussed.

Eye-tracking-based experimental paradigm to assess social-emotional abilities in young individuals with profound intellectual and multiple disabilities.

Individuals with Profound Intellectual and Multiple Disabilities (PIMD) experience a combination of severe cognitive and motor impairments frequently associated with additional sensory deficits and numerous medical disorders. The purpose of the present study was to propose an experimental paradigm based on eye-tracking that combines various pre-existing tasks from infancy research as an assessment tool. This would enable the investigation of social-emotional abilities in nine young individuals with PIMD through their visual preferences for different types of stimuli. The first objective was to test the feasibility of this paradigm, by expecting individuals to look more at the tasks' presentation screen than elsewhere during its implementation. The second objective was to investigate whether PIMD individuals exhibit visual preferences for (a) biological (vs. non-biological) motion, (b) socially salient (vs. non-social) scenes, (c) the facial area of the eyes (vs. the mouth), (d) happy (vs. angry) faces, (e) objects of joint attention (vs. non-looked at ones), and for (f) prosocial (vs. anti-social) behaviors similar to those of a control group of typically developing children aged two years on average. Overall, the feasibility of this paradigm proved to be good, resulting in high individual looking rates that were not affected by the presentation or the content of the tasks. Analyses of individual social-emotional abilities, supported by the visual preference patterns of each PIMD individual, firstly revealed strong-but expected-variability both within and between subjects, and secondly highlighted some individual task-specific abilities although few similarities between these individual results and those of the control group were found. These findings underline the great relevance of using this type of paradigm for assessing PIMD individuals and thus contribute to a better understanding of their social and emotional development.

Anxiety and Spatial Navigation in Williams Syndrome and Down Syndrome.

Individuals with Down Syndrome (DS) and individuals with Williams syndrome (WS) present with poor navigation and elevated anxiety. The aim of this study was to determine the relationship between these two characteristics. Parent report questionnaires measured navigation abilities and anxiety in WS (N = 55) and DS (N = 42) as follows. Anxiety: Spence Children's Anxiety Scale and a novel measure of navigation anxiety. Navigation: Santa Barbara Sense of Direction Scale (SBSOD) and a novel measure of navigation competence. Most individuals were not permitted to travel independently. A relationship between navigation anxiety and SBSOD scores (but not navigation competence) was observed for both groups.

Spatial Cognition in Children With Physical Disability; What Is the Impact of Restricted Independent Exploration?

Given the developmental inter-relationship between motor ability and spatial skills, we investigated the impact of physical disability (PD) on spatial cognition. Fifty-three children with special educational needs including PD were divided into those who were wheelchair users (n = 34) and those with independent locomotion ability (n = 19). This division additionally enabled us to determine the impact of limited independent physical exploration (i.e., required wheelchair use) on spatial competence. We compared the spatial performance of children in these two PD groups to that of typically developing (TD) children who spanned the range of non-verbal ability of the PD groups. Participants completed three spatial tasks; a mental rotation task, a spatial programming task and a desktop virtual reality (VR) navigation task. Levels of impairment of the PD groups were broadly commensurate with their overall level of non-verbal ability. The exception to this was the performance of the PD wheelchair group on the mental rotation task, which was below that expected for their level of non-verbal ability. Group differences in approach to the spatial programming task were evident in that both PD groups showed a different error pattern from the TD group. These findings suggested that for children with both learning difficulties and PD, the unique developmental impact on spatial ability of having physical disabilities, over and above the impact of any learning difficulties, is minimal.

On the Developmental Trajectories of Relational Concepts Among Children and Adolescents With Intellectual Disability of Undifferentiated Etiology.

The aim of this study was to examine the developmental trajectories of comprehension of relational concepts among 557 participants with intellectual disability (ID) of undifferentiated etiology (M age  =  12.20 years, SD  =  3.18) and 557 typically developing (TD) participants (M age  =  4.57 years, SD  =  0.80). Logistic regression analyses, with nonverbal cognitive level entered first in the equations, showed only negligible differences with regard to the discriminative power of each of the 72 concepts used as outcome variables, and moderate differences in difficulty for only three items. A moderate mixed effect (i.e., combining a group difference in difficulty and discriminative power) was observed for a fourth item. It is concluded that the developmental trajectories of relational concepts are similar for participants with or without ID. The implications and limitations of the study are discussed.

Description of Routes in People With Intellectual Disability.

The ability to describe routes was assessed in participants with intellectual disability (ID) and participants without ID matched on chronological age (CA) or on mental age (MA). In two experiments, participants learned a route through a virtual environment until they reached a learning criterion. They were then asked to externalize their spatial knowledge in a verbal description task, a landmark recognition task, or a map completion task. Results revealed that participants with ID mainly described the route as a succession of actions ("turn left"), and participants in the CA group prescribed actions referring to a landmark ("turn left at the swing"). Yet, results from the other tasks showed that people with ID had good landmark knowledge of the environment.

Using virtual environments to investigate wayfinding in 8- to 12-year-olds and adults.

Wayfinding is the ability to learn and recall a route through an environment. Theories of wayfinding suggest that for children to learn a route successfully, they must have repeated experience of it, but in this experiment we investigated whether children could learn a route after only a single experience of the route. A total of 80 participants from the United Kingdom in four groups of 20 8-year-olds, 10-year-olds, 12-year-olds, and adults were shown a route through a 12-turn maze in a virtual environment. At each junction, there was a unique object that could be used as a landmark. Participants were "walked" along the route just once (without any verbal prompts) and then were asked to retrace the route from the start without any help. Nearly three quarters of the 12-year-olds, half of the 10-year-olds, and a third of the 8-year-olds retraced the route without any errors the first time they traveled it on their own. This finding suggests that many young children can learn routes, even with as many as 12 turns, very quickly and without the need for repeated experience. The implications for theories of wayfinding that emphasize the need for extensive experience are discussed.

Encouraging 5-year olds to attend to landmarks: a way to improve children's wayfinding strategies in a virtual environment.

Wayfinding is defined as the ability to learn and remember a route through an environment. Previous researchers have shown that young children have difficulties remembering routes. However, very few researchers have considered how to improve young children's wayfinding abilities. Therefore, we investigated ways to help children increase their wayfinding skills. In two studies, a total of 72 5-year olds were shown a route in a six turn maze in a virtual environment and were then asked to retrace this route by themselves. A unique landmark was positioned at each junction and each junction was made up of two paths: a correct path and an incorrect path. Two different strategies improved route learning performance. In Experiment 1, verbally labeling on-route junction landmarks during the first walk reduced the number of errors and the number of trials to reach a learning criterion when the children retraced the route. In Experiment 2, encouraging children to attend to on-route junction landmarks on the first walk reduced the number of errors when the route was retraced. This was the first study to show that very young children can be taught route learning skills. The implications of our results are discussed.

The development of route learning in Down syndrome, Williams syndrome and typical development: investigations with virtual environments.

The ability to navigate new environments has a significant impact on the daily life and independence of people with learning difficulties. The aims of this study were to investigate the development of route learning in Down syndrome (N = 50), Williams syndrome (N = 19), and typically developing children between 5 and 11 years old (N = 108); to investigate use of landmarks; and to relate cognitive functions to route-learning ability in these groups. Overall, measures of attention and long-term memory were strongly associated with route learning, even once non-verbal ability was controlled for. All of the groups, including 5- to 6-year-old TD children, demonstrated the ability to make use of all landmark types to aid route learning; those near junctions, those further from junctions, and also distant landmarks (e.g. church spire, radio mast). Individuals with WS performed better than a matched subset of TD children on more difficult routes; we suggest that this is supported by relatively strong visual feature recognition in the disorder. Participants with DS who had relatively high levels of non-verbal ability performed at a similar level to TD participants.

Route knowledge and configural knowledge in typical and atypical development: a comparison of sparse and rich environments.

BACKGROUND: Individuals with Down syndrome (DS) and individuals with Williams syndrome (WS) have poor navigation skills, which impact their potential to become independent. Two aspects of navigation were investigated in these groups, using virtual environments (VE): route knowledge (the ability to learn the way from A to B by following a fixed sequence of turns) and configural knowledge (knowledge of the spatial relationships between places within an environment). METHODS: Typically developing (TD) children aged 5 to 11 years (N = 93), individuals with DS (N = 29) and individuals with WS (N = 20) were presented with a sparse and a rich VE grid maze. Within each maze, participants were asked to learn a route from A to B and a route from A to C before being asked to find a novel shortcut from B to C. RESULTS: Performance was broadly similar across sparse and rich mazes. The majority of participants were able to learn novel routes, with poorest performance in the DS group, but the ability to find a shortcut, our measure of configural knowledge, was limited for all three groups. That is, 59 % TD participants successfully found a shortcut, compared to 10 % participants with DS and 35 % participants with WS. Differences in the underlying mechanisms associated with route knowledge and configural knowledge and in the developmental trajectories of performance across groups were observed. Only the TD participants walked a shorter distance in the last shortcut trial compared to the first, indicative of increased configural knowledge across trials. The DS group often used an alternative strategy to get from B to C, summing the two taught routes together. CONCLUSIONS: Our findings demonstrate impaired configural knowledge in DS and in WS, with the strongest deficit in DS. This suggests that these groups rely on a rigid route knowledge based method for navigating and as a result are likely to get lost easily. Route knowledge was also impaired in both DS and WS groups and was related to different underlying processes across all three groups. These are discussed with reference to limitations in attention and/or visuo-spatial processing in the atypical groups.

Wayfinding behaviour in Down syndrome: a study with virtual environments.

The aim of this study was to assess wayfinding abilities in individuals with Down syndrome (DS). The ability to learn routes though a virtual environment (VE) and to make a novel shortcut between two locations was assessed in individuals with DS (N=10) and control participants individually matched on mental age (MA) or chronological age (CA). The results showed that most of the participants with DS were able to learn routes through the VE, even though they needed more trials than the CA controls to reach the learning criterion. However, they did not show flexible wayfinding behaviour because they were unable to find a shortcut between two known locations (unlike the CA controls). The results suggest that most individuals with DS can acquire knowledge about specific routes, but are unable to integrate that knowledge into a configurational understanding of the environment.

Short-term memory, executive control, and children's route learning.

The aim of this study was to investigate route-learning ability in 67 children aged 5 to 11years and to relate route-learning performance to the components of Baddeley's model of working memory. Children carried out tasks that included measures of verbal and visuospatial short-term memory and executive control and also measures of verbal and visuospatial long-term memory; the route-learning task was conducted using a maze in a virtual environment. In contrast to previous research, correlations were found between both visuospatial and verbal memory tasks-the Corsi task, short-term pattern span, digit span, and visuospatial long-term memory-and route-learning performance. However, further analyses indicated that these relationships were mediated by executive control demands that were common to the tasks, with long-term memory explaining additional unique variance in route learning.

Colour as an environmental cue when learning a route in a virtual environment: typical and atypical development.

Typically developing (TD) 6-year-olds and 9-year-olds, and older children and adults with Williams syndrome (WS) navigated through brick-wall mazes in a virtual environment. Participants were shown a route through three mazes, each with 6 turns. In each maze the floor of each path section was a different colour such that colour acted as an environmental cue. The colours employed were either easy to verbalise (focal colours) or difficult to verbalise (non-focal colours). We investigated whether participants would verbally code the colour information in the focal colour condition only, and whether this facilitated route-learning. All groups could learn the routes; the WS group required more learning trials to learn the route and achieved lower memory scores than both of the TD groups. Despite this, all groups showed the same pattern of results. There was no effect of condition on the ability to learn the maze. However, when asked which colours featured in each route, higher memory scores were achieved for the focal colour (verbalisable) than the non-focal colour (non-verbalisable) condition. This suggests that, in both young children and individuals with WS, once a route has been learnt, the nature of the environmental cues within it can impact an individual's representation of that route.

How useful are landmarks when learning a route in a virtual environment? Evidence from typical development and Williams syndrome.

The ability to learn a route through a virtual environment was assessed in 19 older children and adults with Williams syndrome (WS) and 40 typically developing (TD) children aged 6-9 years. In addition to comparing route-learning ability across groups, we were interested in whether participants show an adult-like differentiation between "useful" and "less useful" landmarks when learning a route and the relative salience of landmark position versus landmark identity. Each virtual environment consisted of a brick wall maze with six junctions. There were 16 landmarks in the maze, half of which were on the correct path and half on incorrect paths. Results showed that both groups could learn each route to criterion (two successful completions of a route without error). During the learning phase, the WS group produced more errors than the TD group and took longer to reach criterion. This was predominantly due to the large number of perseverative errors (i.e., errors that were made at the same choice point on consecutive learning trials) made by the WS group relative to the TD children. We suggest that this reflects a difficulty in inhibiting erroneous responses in WS. During the test phase, the TD group showed stronger recall of landmarks adjacent to junctions (more useful landmarks) than of landmarks along path sections (less useful landmarks) independent of each individual's level of nonverbal ability. This pattern was also evident in the WS group but was related to level of nonverbal maturation; the differentiation between recall of junction and path landmarks increased as nonverbal ability increased across WS participants. Overall, the results demonstrate that individuals with WS can learn a route but that the development of this ability is atypical.

On the difficulty of relational concepts among participants with Down syndrome.

The aim of the study was to compare the difficulty of relational concepts among participants with and without intellectual disability. The French versions of the Boehm Tests of Basic Concepts Third Edition (Preschool and Kindergarten to 2nd grade) were administered to three groups of 47 participants individually matched on their total raw score on the tests. The first group comprised participants with intellectual disability of undifferentiated etiology, the second, participants with Down syndrome and the third, typical children. Item analyses using the transformed item difficulties method to detect differential item functioning across groups showed that the groups' rank-orders of item difficulty were highly similar. It is concluded that, all things being equal, relational concepts are of comparable difficulty and follow a similar sequence of development whatever the cognitive and etiological status of participants. Methodological and theoretical implications of these findings are discussed.

Route learning and shortcut performance in adults with intellectual disability: a study with virtual environments.

The ability to learn routes though a virtual environment (VE) and to make a novel shortcut between two locations was assessed in 18 adults with intellectual disability and 18 adults without intellectual disability matched on chronological age. Participants explored two routes (A ⇔ B and A ⇔ C) until they reached a learning criterion. Then, they were placed at B and were asked to find the shortest way to C (B ⇔ C, five trials). Participants in both groups could learn the routes, but most of the participants with intellectual disability could not find the shortest route between B and C. However, the results also revealed important individual differences within the intellectual disability group, with some participants exhibiting more efficient wayfinding behaviour than others. Individuals with intellectual disability may differ in the kind of spatial knowledge they extract from the environment and/or in the strategy they use to learn routes.

Mental rotation in Williams syndrome: an impaired ability.

Typically developing young children and individuals with intellectual disabilities often perform poorly on mental rotation tasks when the stimulus they are rotating lacks a salient component. However, performance can be improved when salience is increased. The present study investigated the effect of salience on mental rotation performance by individuals with Williams syndrome. Individuals with Williams syndrome and matched controls were presented with two versions of a mental rotation task: a no salient component condition and a salient component condition. The results showed that component salience did not benefit individuals with Williams syndrome in the same manner as it did controls.

Mental rotation of unfamiliar stimuli by teenagers with mental retardation: role of feature salience.

Teenagers with mental retardation and two groups of children without mental retardation matched on MA or CA carried out mental rotation tasks of unfamiliar stimuli. Three shapes composed of four arms were used. For each shape, there was a version with a salient feature (F+), and a version with no salient feature (F-). Results showed that teenagers with mental retardation could perform mental rotation tasks with unfamiliar stimuli. However, they had a steeper increase in error rate for F- stimuli than did the MA and CA groups. Individuals with mental retardation may have difficulties in performing mental rotation tasks when stimuli have no feature with a salient axis of elongation.