Patterns of differences in wayfinding performance and correlations among abilities between persons with and without Down syndrome and typically developing children

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.

A profile of spatial abilities in people with Down syndrome

BACKGROUND

Spatial abilities are fundamental cognitive abilities, have direct applications in daily life, serve as a cognitive foundation for many other complex skills and are used in many specialty jobs. The current study aimed to systematically and comprehensively evaluate the spatial abilities of individuals with Down syndrome (DS) relative to mental ability-matched typically developing (TD) children based on Newcombe and Shipley's double-dimension theoretical framework for classifying spatial abilities.

METHODS

Forty adolescents and young adults with DS and 40 TD children completed a nonverbal intelligence test (Raven's), two measures of static-extrinsic skills (water-level task and cart task), two measures of static-intrinsic skills (figure ground and form completion), two measures of dynamic-extrinsic skills (three mountains task and dog task) and two measures of dynamic-intrinsic spatial skills (mental rotation task and block design task).

RESULTS

Participants with DS showed reduced performance on two dynamic-intrinsic tasks and one static-extrinsic task (i.e. cart task) relative to TD children. Performances were similar in two dynamic-extrinsic tasks and two static-intrinsic tasks. Analyses of composite accuracy for each spatial category further confirmed deficits in dynamic-intrinsic and static-extrinsic categories for people with DS relative to TD children.

CONCLUSIONS

Our results showed an uneven profile of spatial abilities in people with DS relative to ability-matched TD children with particular weaknesses in comprehending and manipulating dynamic-intrinsic and static-extrinsic spatial relations. Furthermore, our research has important clinical implications for more targeted interventions to improve spatial abilities in people with DS.

Visuospatial perspective taking in people with Down syndrome

Visuospatial perspective taking (VPT) refers to the process of mentally representing a viewpoint different from one's own. It is related to mental rotation and theory of mind and helps to support some complex spatial activities such as wayfinding. Despite research advances in spatial cognition, little is known about VPT in people with Down syndrome (DS). Here, we examined VPT in people with DS. A total of 38 individuals with DS (aged 12-25 years old) and nonverbal ability-matched typically developing (TD) children (aged 4-9 years old) participated. They completed two VPT tasks: the classic Piagetian Three Mountains Task and a modified version of the "Dog Task" (Newcombe & Huttenlocher, 1992). For both groups, the Three Mountains Task was more difficult than the Dog Task, implying the impact of task complexity on assessing VPT. However, the overall performance did not differ between the TD and DS groups in either VPT task. Implications of the results were discussed.

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.

Developmental Trajectories in Spatial Visualization and Mental Rotation in Individuals with Down Syndrome

BACKGROUND

The analysis of developmental trajectories of visuospatial abilities in individuals with Down Syndrome (DS) remains an unexplored field of investigation to examine in depth. The study aimed to fill such a gap by examining changes in two visuospatial abilities: spatial visualization (the ability to manage spatial stimuli) and mental rotation (the ability to rotate spatial stimuli).

METHOD

Eighty-seven participants with DS, aged between 7 and 53 years (forty-seven males and forty females), completed spatial visualization and mental rotation tasks. Changes in these two abilities were analyzed in relation to chronological age and developmental level, the latter derived from Raven's Colored Progressive Matrices.

RESULTS

Chronological age was linearly associated with spatial visualization performance, whereas mental rotation performance increased until 14 years of age and then decreased. Developmental level was linearly associated with increased performance in spatial visualization, the trend in mental rotation was segmented with an increase after 5 years of age. Furthermore, developmental trajectories in mental rotation depended on the rotation degree.

CONCLUSION

Chronological age explains a modest quote of variance. Developmental level better describes changes in spatial visualization and mental rotation of individuals with DS.

Everyday Memory in People with Down Syndrome

Although memory functions in people with Down Syndrome (DS) have been studied extensively, how well people with DS remember things about everyday life is not well understood. In the current study, 31 adolescents/young adults with DS and 26 with intellectual disabilities (ID) of mixed etiology (not DS) participated. They completed an everyday memory questionnaire about personal facts and recent events (e.g., school name, breakfast). They also completed a standard laboratory task of verbal long-term memory (LTM) where they recalled a list of unrelated words over trials. Results did not indicate impaired everyday memory, but impaired verbal LTM, in people with DS relative to people with mixed ID. Furthermore, the laboratory verbal LTM task predicted everyday memory for both groups after taking into account mental age equivalent. Our research showed both an independence and a connection between everyday memory and the standard laboratory memory task and has important research and clinical implications.

Path Learning in Individuals With Down Syndrome: The Challenge of Learning Condition and Cognitive Abilities

Analyzing navigational abilities and related aspects in individuals with Down syndrome (DS) is of considerable interest because of its relevance to everyday life. This study investigates path learning, the conditions favoring it, and the cognitive abilities involved. A group of 30 adults with DS and 32 typically-developing (TD) children matched on receptive vocabulary were shown a 4 × 4 Floor Matrix and asked to repeat increasingly long sequences of steps by walking on the grid. The sequences were presented under two learning conditions, one called Oral instructions (participants received verbal instructions such as “turn right” or “turn left”), the other Observation (participants watched the experimenter's moves). Participants were also assessed on verbal and visuospatial cognitive measures. The results showed a similarly better performance in both groups when the Floor Matrix task was administered in the Observation as opposed to the Oral instructions condition. As for the relation with cognitive abilities, in the Floor Matrix task in the Oral instructions condition, individuals with DS showed an effect of both verbal and visuospatial abilities, which was only positive for verbal ability. The effect of verbal and visuospatial abilities was negligible in the TD group. In the Observation condition, performance was predicted by sequential working memory in both groups. Overall, these results shed light on path learning in individuals with DS, showing that they benefited from the Observation condition, and that the involvement of their cognitive abilities depended on the learning condition.

A Critical Review of Spatial Abilities in Down and Williams Syndromes: Not All Space Is Created Equal

Down syndrome (DS, Trisomy 21) and Williams syndrome (WS) are two neurodevelopmental disorders of genetic origin that are accompanied by mild to moderate intellectual disability but exhibit distinct cognitive profiles. In this review we discuss our recent work characterizing the real-world spatial learning and memory abilities of adult individuals with DS and WS. We used several different paradigms in which participants locomote freely and have access to coherent input from all sensory modalities to investigate their fundamental egocentric (body-centered or viewpoint-dependent) and allocentric (world-centered or viewpoint-independent) spatial abilities. We found unequivocal evidence that most individuals with DS exhibit low-resolution egocentric and allocentric spatial learning and memory abilities similar to typically developing (TD) children in the same mental age range. In contrast, most individuals with DS exhibit impaired high-resolution allocentric spatial learning and facilitated response learning as compared to TD children. In comparison, whereas most individuals with WS also exhibit facilitated response learning, their low-resolution allocentric spatial learning and memory abilities are severely impaired as compared to both TD children and individuals with DS. Together with work from other laboratories using real-world or virtual reality paradigms, these findings indicate that in order to navigate in their environment most individuals with DS may use either egocentric route learning that does not integrate individual landmarks, or a low-resolution allocentric spatial representation that encodes the relationships between different locations (i.e., cognitive mapping). In contrast, since most individuals with WS are unable to build or use a low-resolution allocentric or configural representation of the environment they may use visually and verbally encoded landmarks as beacons to learn routes. Finally, we discuss the main neural structures implicated in these different spatial processes and explain how the relative preservation or impairment of specific brain functions may engender the unique cognitive profiles observed in individuals with these neurodevelopmental disorders.

Executive function in Down syndrome: A meta-analysis

BACKGROUND

Executive function (EF) refers to a set of cognitive processes involved in goal-oriented behavior-especially inhibition, attention shifting, and working memory. EF has been identified as a probable area of difficulty in Down syndrome (DS), but the exact nature of the difficulty has not been well-established.

AIMS

The meta-analysis sought to confirm or disconfirm EF as an area of difficulty in DS and elucidate an EF profile.

METHODS AND PROCEDURES

A random-effects meta-analysis was conducted on 57 studies that compared a group with DS to a typically developing (TD) mental age matched group on one or more executive function tasks. Heterogeneity was examined and moderators analyzed.

OUTCOMES AND RESULTS

The overall mean weighted effect size was large (d = -0.87), indicating poorer EF in groups with DS vs TD groups. Heterogeneity was significant, and moderator analysis revealed an EF profile with a very large effect for verbal WM/STM, a large effect for shifting, and moderate effects for inhibition and nonverbal WM/STM. Skewness analysis suggested that mean effect sizes might have been dampened, especially for WM/STM and shifting.

CONCLUSIONS AND IMPLICATIONS

Individuals with DS display a pronounced difficulty in EFs; implications for interventions and future research are discussed.

Path Integration and Cognitive Mapping Capacities in Down and Williams Syndromes

Williams (WS) and Down (DS) syndromes are neurodevelopmental disorders with distinct genetic origins and different spatial memory profiles. In real-world spatial memory tasks, where spatial information derived from all sensory modalities is available, individuals with DS demonstrate low-resolution spatial learning capacities consistent with their mental age, whereas individuals with WS are severely impaired. However, because WS is associated with severe visuo-constructive processing deficits, it is unclear whether their impairment is due to abnormal visual processing or whether it reflects an inability to build a cognitive map. Here, we tested whether blindfolded individuals with WS or DS, and typically developing (TD) children with similar mental ages, could use path integration to perform an egocentric homing task and return to a starting point. We then evaluated whether they could take shortcuts and navigate along never-traveled trajectories between four objects while blindfolded, thus demonstrating the ability to build a cognitive map. In the homing task, 96% of TD children, 84% of participants with DS and 44% of participants with WS were able to use path integration to return to their starting point consistently. In the cognitive mapping task, 64% of TD children and 74% of participants with DS were able to take shortcuts and use never-traveled trajectories, the hallmark of cognitive mapping ability. In contrast, only one of eighteen participants with WS demonstrated the ability to build a cognitive map. These findings are consistent with the view that hippocampus-dependent spatial learning is severely impacted in WS, whereas it is relatively preserved in DS.

The Acquisition of Survey Knowledge by Individuals With Down Syndrome

People with Down syndrome often exhibit deficiencies in wayfinding activities, particularly route learning (e.g., Courbois et al., 2013; Davis et al., 2014; Farran et al., 2015). Evidence concerning more sophisticated survey learning has been sparse. In the research reported here, two experiments are reported that evaluated survey learning of youth with DS and typically developing children (TD) matched on mental age. In Experiment 1, participants learned two overlapping routes consisting of three turns each through a virtual environment depicting 9 square city blocks. Following acquisition, they were tested on multiple measures of survey knowledge: finding a shortcut, identifying the direction of landmarks not currently visible from their location in the environment, and recognizing a bird's-eye representation of the overall environment. Under these conditions, which should provide relatively optimal opportunities for survey learning, the participants with DS performed comparably to TD participants matched on non-verbal ability on all of our measures of survey learning. Hence, we concluded that people with DS can acquire some survey knowledge when tasked with learning a small environment and given the opportunity to do so. In Experiment 2, the experimenter navigated participants through a large, relatively complex, virtual environment along a circuitous path, beginning and ending at a target landmark. Then, the participants were placed at a pre-specified location in the environment that they had viewed previously and instructed to navigate to the same target (a door) using the shortest possible path from their current location. They completed the task three times: once after being shown the environment one time, once after three exposures, and once after five exposures. Results indicated that the participants with DS exhibited significantly less skill at identifying the shortcut than did the TD participants, with differences emerging as the number of exposures increased. Participants with DS were also less able to recall landmarks at the end of the experiment. Overall, however, the performance of both groups was relatively poor in both experiments - with the performance of participants with DS being worse as conditions became less optimal. These results were discussed in terms of underlying mechanisms that may account for variations in survey learning as environmental complexity increases.

Path Learning in Individuals With Down Syndrome: The Floor Matrix Task and the Role of Individual Visuo-Spatial Measures

Environment learning is essential in everyday life. In individuals with Down syndrome (DS), this skill has begun to be examined using virtual exploration. Previous studies showed that individuals with DS can learn and remember paths in terms of sequences of turns and straight stretches, albeit with some difficulty, and this learning is supported by their cognitive abilities. This study further investigates environment learning in the DS population, newly examining their ability to learn a path from actual movements, and to learn increasingly long paths, and how their performance relates to their visuo-spatial abilities and everyday spatial activities. A group of 30 individuals with DS and 30 typically-developing (TD) children matched for receptive vocabulary performed a 4 × 4 Floor Matrix task in a grid comprising 16 squares (total area 2.3 × 2.3 meters). The task involved repeating increasingly long sequences of steps by actually moving in the grid. The sequences were presented in two learning conditions, called Observation (when participants watched the experimenter’s moves), or Map (when they were shown a map reproducing the path). Several visuo-spatial measures were also administered. The results showed a clear difference between the two groups’ performance in the individual visuo-spatial measures. In the Floor Matrix task, after controlling for visuo-spatial reasoning ability, both groups benefited to the same degree from the Observation condition vis-à-vis the Map condition, and no group differences emerged. In the group with DS, visuo-spatial abilities were more predictive of performance in the Floor Matrix task in the Observation condition than in the Map condition. The same was true of the TD group, but this difference was much less clear-cut. The visuo-spatial working memory and visualization tasks were the strongest predictors of Floor Matrix task performance. Finally, the group with DS showed a significant relation between Floor Matrix task performance in the Observation condition and everyday spatial activity. These results enlarge on what we know about path learning in individuals with DS and its relation to their visuo-spatial abilities. These findings are discussed within the frame of spatial cognition and the atypical development domain.

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.

Accessible and inclusive transportation for youth with disabilities: exploring innovative solutions

Background: Although access to reliable transportation is an essential component of quality of life, young people with disabilities encounter many transportation-related obstacles.Objective: To explore solutions to the challenges that youth with disabilities encounter in accessing and navigating transportation.Methods: A nominal group technique was used in two consultation workshops (one involving rehabilitation clinicians and accessible transportation stakeholders; and one with youth with disabilities and parents). Fifteen participants across two workshops took part and prioritized their solutions and we used a comparative analysis within and between groups to explore overarching themes.Results: The workshops resulted in 122 solutions (76 from youth/parents; 46 from stakeholders). Although there was considerable overlap within the ideas generated between the groups, they each prioritized them differently. The following themes emerged across the two group's prioritized solutions: training, funding, enhancing access, and improved efficiency.Conclusions: Our findings highlight that youth with disabilities, parents and key stakeholders offered many practical solutions for enhancing accessible transportation for youth with disabilities.Implications for RehabilitationClinicians and educators should explore different apps and transportation training programs that could help support youth with disabilities to enhance their independence and participation in the communityClinicians and educators should be involved in the development of disability awareness training programs for public transit and school bus drivers to enhance youth's inclusion and participation in society.Clinicians, educators, youth and parents should continue to advocate for inclusive, accessible, affordable and efficient transportation for people with disabilities.

Pedestrian navigation and public transit training interventions for youth with disabilities: a systematic review

Purpose: Being able to travel independently, whether as a pedestrian or by taking public transportation, is a critical element to maintaining quality of life and participation in the community. The objective of this systematic review is to understand the best practices and effective components of pedestrian and public transit training interventions for youth with disabilities. Method: Systematic searches of seven international databases identified 29 studies meeting our inclusion criteria. We analyzed these studies based on participant characteristics, methods, results, and quality of evidence. Results: Among the 29 studies, 857 participants (aged 5-39, mean 18.3 years) were represented across 10 countries. Although the intervention outcomes varied across the studies, 24 of them reported an improvement in at least one of the following: pedestrian and general navigation skills, pedestrian safety, landmark recognition, route knowledge, and public transportation skills. Conclusions: Our findings highlight that pedestrian and public transit interventions have the potential to improve the participation and quality of life of children and youth with disabilities. More rigorous, theoretically informed interventions, using standardized measures are needed to enhance pedestrian and transit training skills among youth with disabilities. Implications for rehabilitation Travel training interventions have the potential to effectively support youth with disabilities in learning pedestrian and public transportation navigation skills. Clinicians and educators should encourage youth with disabilities to participate in travel training programs enhance their independence skills and participation in the community. Clinicians, educators, and program managers can help to build relevant content for travel training programs and connect youth to programs.

Memory profiles in Down syndrome across development: a review of memory abilities through the lifespan

Down syndrome (DS) is associated with a variety of cognitive impairments, notably memory impairments. Due to the high prevalence rates of early-onset dementia associated with DS, it is imperative to understand the comprehensive development of memory impairments beginning in childhood and into adulthood, as this may help researchers identify precursors of dementia at earlier stages of development and pinpoint targets for memory intervention. The current paper provides a systematic, developmentally focused review of the nature of memory difficulties in DS across the lifespan. Specifically, this review summarizes what is known about long-term, short-term, and working memory abilities (distinguishing between verbal and nonverbal modalities) in DS, compared to both mental age-matched typically developing peers and individuals with other forms of intellectual disability (ID) at three developmental stages (i.e., preschool, adolescence, and adulthood). Additionally, this review examines the degree of impairment reported relative to typically developing mental age-matched peers in the existing literature by examining effect size data across memory domains as a function of age. With few exceptions, memory abilities were impaired across the lifespan compared to mental age-matched typically developing peers. Relative to other groups with ID, research findings are mixed. Our review of the literature identified a scarcity of memory studies in early childhood, particularly for STM and WM. In adulthood, research was limited in the LTM and WM domains and very little research has compared memory abilities in older adults with DS to those with typical development. Looking to the future, longitudinal studies could provide a better understanding of the developmental trajectory of memory abilities in DS, and the possible associations between memory abilities and real-world functioning. This research could ultimately inform interventions to improve independence and overall quality of life for those with DS and their families.

Mental rotation ability and everyday-life spatial activities in individuals with Down syndrome

Although certain visuospatial abilities, such as mental rotation, are crucially important in everyday activities, they have been little explored in individuals with Down syndrome (DS). This study investigates: i) mental rotation ability in individuals with DS; and ii) its relation to cognitive abilities and to everyday spatial activities. Forty-eight individuals with DS and 48 typically-developing (TD) children, matched on measures of vocabulary and fluid intelligence, were compared on their performance in a rotation task that involved detecting which of two figures would fit into a hole if rotated (five angles of rotation were considered: 0°, 45°, 90°, 135°, 180°). Participants were also assessed on their visuospatial and verbal cognitive abilities, and on their parents and/or educators reports regarding their everyday spatial activities. Results showed that: (i) individuals with DS were less accurate in mental rotation than TD children, with larger differences between the groups for smaller angles of rotation; individuals with DS could not mentally rotate through 180°, while TD children could; (ii) mental rotation ability was related to fluid intelligence and to spatial activities (though other cognitive abilities are also involved in the latter) to a similar degree in the DS group and the matched TD children. These results are discussed with regard to the atypical development domain and spatial cognition models.

Environment learning from virtual exploration in individuals with down syndrome: the role of perspective and sketch maps

BACKGROUND

Spatial knowledge about an environment is an important determinant of ability to move effectively within it and of personal autonomy. Individuals with Down's syndrome (DS) have difficulty managing configural visuospatial information.

METHOD

Twenty-nine individuals with DS and 29 typically developing (TD) children, matched for mental age, learned about environments through virtual exploration using a route or survey view. A sketch map of the environment was or was not presented before exploration. Then the acquisition of configural knowledge (landmark locations) and route retracing were tested.

RESULTS

Individuals with DS were able to acquire configural knowledge through virtual exploration in all presentation conditions, and generally performed no worse than matched TD children. However, they were not able to benefit from the conditions that facilitated acquisition of configural knowledge in TD children, that is, seeing a sketch map before exploring and exploring in survey (rather than route) view. As regards route retracing, individuals with DS paused more often than controls and tended to travel longer paths, which made them slower overall.

CONCLUSIONS

DS reduces children's ability to benefit from additional survey information and may be related to difficulty in elaborating configural/simultaneous information.

Visuo-spatial knowledge acquisition in individuals with Down syndrome: The role of descriptions and sketch maps

Few studies on individuals with Down syndrome (DS) have explored how they learn space. The present study examines space learning from verbal descriptions in individuals with DS, and explores the role of external cues (such as a sketch map). Twenty-eight individuals with DS and 28 matched typically-developing (TD) children listened to route or survey descriptions with or without seeing a corresponding sketch map (Description+Sketch Map [D+SM] and Description alone [D], respectively). After hearing each description, they performed tasks that involved recognizing, arranging sequentially, and locating landmarks. The results showed that individuals with DS performed less well in recognizing landmarks and arranging them sequentially. The D+SM condition produced general benefits in both groups' accuracy, though the improvement in locating landmarks was greater in the TD than in the DS group. In both groups, the D+SM condition prompted a better performance than the D condition when participants arranged landmarks sequentially after hearing a description from a route perspective, but not from a survey perspective. Overall, our results show that individuals with DS benefited when a spatial description was associated with a corresponding sketch map, albeit to a lesser degree than TD children. The findings are discussed in the light of the literature on DS and on spatial cognition in the TD domain.

Sex Differences in Using Spatial and Verbal Abilities Influence Route Learning Performance in a Virtual Environment: A Comparison of 6- to 12-Year Old Boys and Girls

Previous studies have reported sex differences in wayfinding performance among adults. Men are typically better at using Euclidean information and survey strategies while women are better at using landmark information and route strategies. However, relatively few studies have examined sex differences in wayfinding in children. This research investigated relationships between route learning performance and two general abilities: spatial ability and verbal memory in 153 boys and girls between 6- to 12-years-old. Children completed a battery of spatial ability tasks (a two-dimension mental rotation task, a paper folding task, a visuo-spatial working memory task, and a Piagetian water level task) and a verbal memory task. In the route learning task, they had to learn a route through a series of hallways presented via computer. Boys had better overall route learning performance than did girls. In fact, the difference between boys and girls was constant across the age range tested. Structural equation modeling of the children’s performance revealed that spatial abilities and verbal memory were significant contributors to route learning performance. However, there were different patterns of correlates for boys and girls. For boys, spatial abilities contributed to route learning while verbal memory did not. In contrast, for girls both spatial abilities and verbal memory contributed to their route learning performance. This difference may reflect the precursor of a strategic difference between boys and girls in wayfinding that is commonly observed in adults.

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.