Balance, gait, and navigation performance are related to physical exercise in blind and visually impaired children and adolescents.

Self-motion perception used for locomotion and navigation requires the integration of visual, vestibular, and proprioceptive input. In the absence of vision, postural stability and locomotor tasks become more difficult. Previous research has suggested that in visually deprived children, postural stability and levels of physical activity are overall lower than in sighted controls. Here we hypothesized that visually impaired and blind children and adolescents differ from sighted controls in postural stability and gait parameters, and that physically active individuals outperform sedentary peers in postural stability and gait parameters as well as in navigation performance. Fourteen blind and visually impaired children and adolescents (8-18 years of age) and 14 matched sighted individuals took part. Assessments included postural sway, single-leg stance time, parameters of gait variability and stability, self-reported physical activity, and navigation performance. Postural sway was larger and single-leg stance time was lower in blind and visually impaired participants than in blindfolded sighted individuals. Physical activity was higher in the sighted group. No differences between the group of blind and visually impaired and blindfolded sighted participants were observed for gait parameters and navigation performance. Higher levels of physical activity were related to lower postural sway, longer single-leg stance time, higher gait stability, and superior navigation performance in blind and visually impaired participants. The present data suggest that physical activity may enhance postural stability and gait parameters, and thereby promote navigation performance in blind and visually impaired children and adolescents.

Allocentric spatial perception through vision and touch in sighted and blind children.

Vision and touch play a critical role in spatial development, facilitating the acquisition of allocentric and egocentric frames of reference, respectively. Previous works have shown that children's ability to adopt an allocentric frame of reference might be impaired by the absence of visual experience during growth. In the current work, we investigated whether visual deprivation also impairs the ability to shift from egocentric to allocentric frames of reference in a switching-perspective task performed in the visual and haptic domains. Children with and without visual impairments from 6 to 13 years of age were asked to visually (only sighted children) or haptically (blindfolded sighted children and blind children) explore and reproduce a spatial configuration of coins by assuming either an egocentric perspective or an allocentric perspective. Results indicated that temporary visual deprivation impaired the ability of blindfolded sighted children to switch from egocentric to allocentric perspective more in the haptic domain than in the visual domain. Moreover, results on visually impaired children indicated that blindness did not impair allocentric spatial coding in the haptic domain but rather affected the ability to rely on haptic egocentric cues in the switching-perspective task. Finally, our findings suggested that the total absence of vision might impair the development of an egocentric perspective in case of body midline-crossing targets.

Auditory and proprioceptive spatial impairments in blind children and adults.

It is not clear what role visual information plays in the development of space perception. It has previously been shown that in absence of vision, both the ability to judge orientation in the haptic modality and bisect intervals in the auditory modality are severely compromised (Gori, Sandini, Martinoli & Burr, 2010; Gori, Sandini, Martinoli & Burr, 2014). Here we report for the first time also a strong deficit in proprioceptive reproduction and audio distance evaluation in early blind children and adults. Interestingly, the deficit is not present in a small group of adults with acquired visual disability. Our results support the idea that in absence of vision the audio and proprioceptive spatial representations may be delayed or drastically weakened due to the lack of visual calibration over the auditory and haptic modalities during the critical period of development.

Recognizing the same face in different contexts: Testing within-person face recognition in typical development and in autism.

Unfamiliar face recognition follows a particularly protracted developmental trajectory and is more likely to be atypical in children with autism than those without autism. There is a paucity of research, however, examining the ability to recognize the same face across multiple naturally varying images. Here, we investigated within-person face recognition in children with and without autism. In Experiment 1, typically developing 6- and 7-year-olds, 8- and 9-year-olds, 10- and 11-year-olds, 12- to 14-year-olds, and adults were given 40 grayscale photographs of two distinct male identities (20 of each face taken at different ages, from different angles, and in different lighting conditions) and were asked to sort them by identity. Children mistook images of the same person as images of different people, subdividing each individual into many perceived identities. Younger children divided images into more perceived identities than adults and also made more misidentification errors (placing two different identities together in the same group) than older children and adults. In Experiment 2, we used the same procedure with 32 cognitively able children with autism. Autistic children reported a similar number of identities and made similar numbers of misidentification errors to a group of typical children of similar age and ability. Fine-grained analysis using matrices revealed marginal group differences in overall performance. We suggest that the immature performance in typical and autistic children could arise from problems extracting the perceptual commonalities from different images of the same person and building stable representations of facial identity.

Proportional Reasoning Deficit in Dyslexia.

Dyslexia has been linked to an altered perception of metrical structures in language, but no study to date has explored the link between reading impairments and other forms of metrical thinking (e.g., proportional reasoning). In the present study, we assessed proportional reasoning in 16 dyslexic children and 16 age-matched controls from 7 to 10 years of age in order to investigate whether dyslexia might be also linked to an altered form of metrical thinking. We found that dyslexic children are less accurate in performing judgments about proportionality compared to typical peers and that reading accuracy correlates with proportional reasoning abilities for 7-8-year-old children. Overall, these findings suggest that a link exists between reading and proportional reasoning abilities. We might speculate that fostering reasoning based on the meter can facilitate reading because it permits the segmentation of words in syllables and that dyslexia can be identified early with alternative non-reading tasks such as the proportional reasoning task used in this work.

Primary Schoolers' Response to a Multisensory Serious Game on Cartesian Plane Coordinates in Immersive Virtual Reality.

The Cartesian coordinate system is a fundamental concept for mathematics and science and poses a teaching challenge at primary school level. Learning the Cartesian coordinate system has the potential to promote numerical cognition through number-space associations, as well as core geometric concepts, including isometric transformations, symmetry, and shape perception. Immersive virtual reality (VR) facilitates embodied forms of teaching and learning mathematics through whole-body sensorimotor interaction and offers benefits as a platform to learn the Cartesian coordinate system compared with "real world" classroom activities. Our goal was to validate the Cartesian-Garden, a serious game designed to provide an educationally robust but engaging vehicle to teach these concepts in primary-level mathematics in a multisensory VR environment. In the game, the child explores a Cartesian-Garden, that is, a field of flowers in which each flower corresponds to x and y coordinates. Specifically, we tested whether exploring numbers spatially represented improved spatial and numerical skills independently from the use of VR. Children (n = 49; age 7-11 years old) were divided into experimental and age-matched control groups. The experimental group explored the Cartesian-Garden and picked flowers corresponding to target coordinates; the control group played a VR game unrelated to Cartesian coordinates. To quantify potential improvements, children were tested before and after training with perceptual tests investigating number line and spatial thinking. The results point toward differential age-related improvements depending on the tested concept, especially for the number line. This study provides the guidelines for the successful use of the Cartesian-Garden game, beneficial for specific age groups.

Clinical assessment of the TechArm system on visually impaired and blind children during uni- and multi-sensory perception tasks.

We developed the TechArm system as a novel technological tool intended for visual rehabilitation settings. The system is designed to provide a quantitative assessment of the stage of development of perceptual and functional skills that are normally vision-dependent, and to be integrated in customized training protocols. Indeed, the system can provide uni- and multisensory stimulation, allowing visually impaired people to train their capability of correctly interpreting non-visual cues from the environment. Importantly, the TechArm is suitable to be used by very young children, when the rehabilitative potential is maximal. In the present work, we validated the TechArm system on a pediatric population of low-vision, blind, and sighted children. In particular, four TechArm units were used to deliver uni- (audio or tactile) or multi-sensory stimulation (audio-tactile) on the participant's arm, and subject was asked to evaluate the number of active units. Results showed no significant difference among groups (normal or impaired vision). Overall, we observed the best performance in tactile condition, while auditory accuracy was around chance level. Also, we found that the audio-tactile condition is better than the audio condition alone, suggesting that multisensory stimulation is beneficial when perceptual accuracy and precision are low. Interestingly, we observed that for low-vision children the accuracy in audio condition improved proportionally to the severity of the visual impairment. Our findings confirmed the TechArm system's effectiveness in assessing perceptual competencies in sighted and visually impaired children, and its potential to be used to develop personalized rehabilitation programs for people with visual and sensory impairments.

Effects of audio-motor training on spatial representations in long-term late blindness.

Vision plays a pivotal role in the development of spatial representation. When visual feedback is absent, complex spatial representations are impaired and temporal properties of auditory information are used by blind people to build spatial maps. Specifically, late blind (LB) adults that have spent more than 20 years without vision (i.e., long-term LB) represent space based on temporal cues. In the present study, we investigate whether audio-motor training based on body feedback modifies the way in which long-term LB adults create spatial representations of the environment. Three long-term LB adults performed a battery of spatial tasks before and after four weeks of training, while three long-term LB adults performed the same tasks before and after four weeks without attending any training. Tasks included: i) an EEG recording during a spatial bisection task with coherent or conflicting spatiotemporal information, ii) auditory vertical and horizontal localization paradigms where participants indicated the final position of a moving sound source, iii) proprioceptive-motor paradigms where participants discriminated the end point of arm movements. The training consisted of specific exercises based on upper-limb movements with auditory feedback from a bracelet device and auditory paths. Our findings suggest that training produces a beneficial effect on some spatial competencies and tends to induce a cortical reorganization of occipital areas sensitive to spatial instead of temporal coordinates of sounds.

Visual Function Score: A New Clinical Tool to Assess Visual Function and Detect Visual Disorders in Children.

Introduction: A comprehensive assessment of visual functioning at an early age is important not only for identifying and defining visual impairment but also for planning personalized rehabilitation programs based on the visual diagnosis. Since existing tools to evaluate visual functioning present some important limitations (e.g., they are based on qualitative reports, they do not take into account environmental adaptations of visual testing or they have not been formally validated as clinical instruments), the present work has the main aim to propose a new clinical tool (Visual Function Score, VFS) to detect and define visual disorders at an early age. Methods: The Visual Function Score was administered to one hundred visually impaired children (age range 4 months to 17.75 years old) in the form of a professional-reported protocol for a total of 51 items, each of which is assigned a score from 1 to 9 (or from 0 to 9 in some specific cases). The VFS produces three sub-scores and a global score (from 0 to 100), resulting in a quantitative evaluation of visual functioning. Results: The VFS can detect the well-known differences between different types of visual impairment (cerebral, oculomotor, and peripheral or grouped as central and peripheral) and takes into account different environments in the definition of a quantitative score of visual functioning. Discussion: Overall, the use of a quantitative tool to evaluate visual functions and functional vision such as the VFS would be fundamental to monitor the progresses of patients over time in response to rehabilitation interventions.

Effects of Increasing Stimulated Area in Spatiotemporally Congruent Unisensory and Multisensory Conditions.

Research has shown that the ability to integrate complementary sensory inputs into a unique and coherent percept based on spatiotemporal coincidence can improve perceptual precision, namely multisensory integration. Despite the extensive research on multisensory integration, very little is known about the principal mechanisms responsible for the spatial interaction of multiple sensory stimuli. Furthermore, it is not clear whether the size of spatialized stimulation can affect unisensory and multisensory perception. The present study aims to unravel whether the stimulated area's increase has a detrimental or beneficial effect on sensory threshold. Sixteen typical adults were asked to discriminate unimodal (visual, auditory, tactile), bimodal (audio-visual, audio-tactile, visuo-tactile) and trimodal (audio-visual-tactile) stimulation produced by one, two, three or four devices positioned on the forearm. Results related to unisensory conditions indicate that the increase of the stimulated area has a detrimental effect on auditory and tactile accuracy and visual reaction times, suggesting that the size of stimulated areas affects these perceptual stimulations. Concerning multisensory stimulation, our findings indicate that integrating auditory and tactile information improves sensory precision only when the stimulation area is augmented to four devices, suggesting that multisensory interaction is occurring for expanded spatial areas.

Togetherness, beyond the eyes: A systematic review on the interaction between visually impaired children and their parents.

BACKGROUND: Parent-child interaction is essential to promote adaptive emotional, cognitive, and social development. The majority of previous research on parent-child interaction is largely dependent on face-to-face exchanges that require the interactive partners to visually recognize reciprocal communicative bids. Therefore, previous findings in the field can only partially apply to the early interactive patterns occurring between visually impaired infants and their parents. The present study was aimed to systematically review the available evidence on parent-child interaction in the context of developmental visual impairment. METHODS: Fourteen papers were finally selected after literature search on PubMed and Scopus. Data synthesis was focused on three core topics: visually impaired children's contribution to the interaction, parental caregiving behaviors with visually impaired children, and the association between parents' behaviors and the developmental outcomes of children with visual impairment. RESULTS: Visually impaired children may exhibit reduced reactivity to maternal stimuli and less-than-optimal levels of interactive initiations in social exchanges. Parents of children with visual impairment may use more descriptive communicative acts and greater directiveness compared to mothers of sighted counterparts. Specific caregiving behaviors (e.g., responsiveness and goal setting) of parents of children with visual impairment may significantly support language and socio-emotional development as well as sensorimotor integration. DISCUSSION: Children with visual impairment may be less responsive and they may produce less clear communicative bids while interacting with their parents. Their parents may face specific challenges while engaging with them and they may become increasingly directive and intrusive. Nonetheless, even in the presence of visual impairment, the quality of parental caregiving behaviors appears to play a potential preventive role in the face of children's socio-emotional and cognitive outcomes. These results suggest that early interventions focused on parent-child interactions are especially needed in this population.

The influence of yaw rotation on spatial navigation during development.

Sensory cues enable navigation through space, as they inform us about movement properties, such as the amount of travelled distance and the heading direction. In this study, we focused on the ability to spatially update one's position when only proprioceptive and vestibular information is available. We aimed to investigate the effect of yaw rotation on path integration across development in the absence of visual feedback. To this end, we utilized the triangle completion task: participants were guided through two legs of a triangle and asked to close the shape by walking along its third imagined leg. To test the influence of yaw rotation across development, we tested children between 6 and 11 years old (y.o.) and adults on their perceptions of angles of different degrees. Our results demonstrated that the amount of turn while executing the angle influences performance at all ages, and in some aspects, also interacted with age. Indeed, whilst adults seemed to adjust their heading towards the end of their walked path, younger children took less advantage of this strategy. The amount of disorientation the path induced also affected participants' full maturational ability to spatially navigate with no visual feedback. Increasing induced disorientation required children to be older to reach adult-level performance. Overall, these results provide novel insights on the maturation of spatial navigation-related processes.

Shape Recognition With Sounds: Improvement in Sighted Individuals After Audio-Motor Training.

Recent studies have demonstrated that audition used to complement or substitute visual feedback is effective in conveying spatial information, e.g., sighted individuals can understand the curvature of a shape when solely auditory input is provided. Recently we also demonstrated that, in the absence of vision, auditory feedback of body movements can enhance spatial perception in visually impaired adults and children. In the present study, we assessed whether sighted adults can also improve their spatial abilities related to shape recognition with an audio-motor training based on the idea that the coupling of auditory and motor information can further refine the representation of space when vision is missing. Auditory shape recognition was assessed in 22 blindfolded sighted adults with an auditory task requiring participants to identify four shapes by means of the sound conveyed through a set of consecutive loudspeakers embedded on a fixed two-dimensional vertical array. We divided participants into two groups of 11 adults each, performing a training session in two different modalities: active audio-motor training (experimental group) and passive auditory training (control group). The audio-motor training consisted in the reproduction of specific movements with the arm by relying on the sound produced by an auditory source positioned on the wrist of participants. Results showed that sighted individuals improved the recognition of auditory shapes only after active training, suggesting that audio-motor feedback can be an effective tool to enhance spatial representation when visual information is lacking.

The Impact of Vision Loss on Allocentric Spatial Coding.

Several works have demonstrated that visual experience plays a critical role in the development of allocentric spatial coding. Indeed, while children with a typical development start to code space by relying on allocentric landmarks from the first year of life, blind children remain anchored to an egocentric perspective until late adolescence. Nonetheless, little is known about when and how visually impaired children acquire the ability to switch from an egocentric to an allocentric frame of reference across childhood. This work aims to investigate whether visual experience is necessary to shift from bodily to external frames of reference. Children with visual impairment and normally sighted controls between 4 and 9 years of age were asked to solve a visual switching-perspective task requiring them to assume an egocentric or an allocentric perspective depending on the task condition. We hypothesize that, if visual experience is necessary for allocentric spatial coding, then visually impaired children would have been impaired to switch from egocentric to allocentric perspectives. Results support this hypothesis, confirming a developmental delay in the ability to update spatial coordinates in visually impaired children. It suggests a pivotal role of vision in shaping allocentric spatial coding across development.

Standardized and Experimental Tools to Assess Spatial Cognition in Visually Impaired Children: A Mini-Review.

The acquisition of spatial cognition is essential for both everyday functioning (e.g., navigation) and more specific goals (e.g., mathematics), therefore being able to assess and monitor spatial cognition from the first years of life would be essential to predict developmental outcomes and timely intervene whenever spatial development is compromised. Several shreds of evidence have indicated that spatial development can be compromised in the case of development with atypical sensory experience such as blindness. Despite the massive importance of spatial abilities for the development of psychomotor competencies across childhood, only a few standardized and experimental methods have been developed to assess them in visually impaired children. In this review, we will give a short overview of current formal (standardized) and informal (experimental) methods to assess spatial cognition in visually impaired children, demonstrating that very few validated tools have been proposed to date. The main contribution of this current work is to highlight the need of ad hoc studies to create and validate clinical measures to assess spatial cognition in visually impaired individuals and address potential future developments in this area of research.

A Multidimensional, Multisensory and Comprehensive Rehabilitation Intervention to Improve Spatial Functioning in the Visually Impaired Child: A Community Case Study.

Congenital visual impairment may have a negative impact on spatial abilities and result in severe delays in perceptual, social, motor, and cognitive skills across life span. Despite several evidences have highlighted the need for an early introduction of re-habilitation interventions, such interventions are rarely adapted to children's visual capabilities and very few studies have been conducted to assess their long-term efficacy. In this work, we present a case study of a visually impaired child enrolled in a newly developed re-habilitation intervention aimed at improving the overall development through the diversification of re-habilitation activities based on visual potential and developmental profile, with a focus on spatial functioning. We argue that intervention for visually impaired children should be (a) adapted to their visual capabilities, in order to increase re-habilitation outcomes, (b) multi-interdisciplinary and multidimensional, to improve adaptive abilities across development, (c) multisensory, to promote the integration of different perceptual information coming from the environment.

Audio-Motor Training Enhances Auditory and Proprioceptive Functions in the Blind Adult.

Several reports indicate that spatial perception in blind individuals can be impaired as the lack of visual experience severely affects the development of multisensory spatial correspondences. Despite the growing interest in the development of technological devices to support blind people in their daily lives, very few studies have assessed the benefit of interventions that help to refine sensorimotor perception. In the present study, we directly investigated the impact of a short audio-motor training on auditory and proprioceptive spatial perception in blind individuals. Our findings indicate that auditory and proprioceptive spatial capabilities can be enhanced through interventions designed to foster sensorimotor perception in the form of audio-motor correspondences, demonstrating the importance of the early introduction of sensorimotor training in therapeutic intervention for blind individuals.

Test-retest reliability of BSP, a battery of tests for assessing spatial cognition in visually impaired children.

Blind individuals are particularly dependent on their hearing for defining space. It has been found that both children and adults with visual impairments can struggle with complex spatial tasks that require a metric representation of space. Nonetheless the variability of methods employed to assess spatial abilities in absence of vision is wide, especially in the case of visually impaired children. For this reason, it would be necessary to define a battery of tests that appropriately assess different aspects of spatial perception and to investigate its reliability in order to provide a standard assessment of spatial abilities not only in experimental but also in clinical settings. The aim of this study is to determine the test-retest reliability of a battery of six spatial tasks (BSP, Blind Spatial Perception) and provide the first gold standard for assessing spatial cognition deficits in visually impaired children. Thirty visually impaired children aged 6-17 participated in two identical sessions, at a distance of 10 weeks, in which they performed six spatial tasks: auditory bisection, auditory localization, auditory distance discrimination, auditory reaching, proprioceptive reaching, and general mobility. Test-retest reliability was assessed using the test-retest scatter plots, intra-class correlation coefficient (ICC), and coefficient of variation (CV). The results showed good-to-excellent reliability for all six tests, with average ICC values ranging from 0.77 to 0.89 and average CV values ranging from 3.44% to 15.27%. In conclusion, the newly proposed battery (BSP) results as a reliable tool to identify spatial impairments in visually impaired children.

Coarse to Fine Audio-Visual Size Correspondences Develop During Primary School Age.

Developmental studies have shown that children can associate visual size with non-visual and apparently unrelated stimuli, such as pure tone frequencies. Most research to date has focused on audio-visual size associations by showing that children can associate low pure tone frequencies with large objects, and high pure tone frequencies with small objects. Researchers relate these findings to coarser association, i.e., less precise associations for which binary categories of stimuli are used such as in the case of low versus high frequencies and large versus small visual stimuli. This study investigates how finer, more precise, crossmodal audio-visual associations develop during primary school age (from 6 to 11 years old). To unveil such patterns, we took advantage of a range of auditory pure tones and tested how primary school children match sounds with visually presented shapes. We tested 66 children (6-11 years old) in an audio-visual matching task involving a range of pure tone frequencies. Visual stimuli were circles or angles of different sizes. We asked participants to indicate the shape matching the sound. All children associated large objects/angles with low pitch, and small objects/angles with high pitch sounds. Interestingly, older children made greater use of intermediate visual sizes to provide their responses. Indeed, audio-visual associations for finer differences between stimulus features such as size and pure tone frequencies, may develop later depending on the maturation of supramodal size perception processes. Considering our results, we suggest that audio-visual size correspondences can be used for educational purposes by aiding the discrimination of sizes, including angles of different aperture. Moreover, their use should be shaped according to children's specific developmental stage.

Audio motor training improves mobility and spatial cognition in visually impaired children.

Since it has been demonstrated that spatial cognition can be affected in visually impaired children, training strategies that exploit the plasticity of the human brain should be early adopted. Here we developed and tested a new training protocol based on the reinforcement of audio-motor associations and thus supporting spatial development in visually impaired children. The study involved forty-four visually impaired children aged 6-17 years old assigned to an experimental (ABBI training) or a control (classical training) rehabilitation conditions. The experimental training group followed an intensive but entertaining rehabilitation for twelve weeks during which they performed ad-hoc developed audio-spatial exercises with the Audio Bracelet for Blind Interaction (ABBI). A battery of spatial tests administered before and after the training indicated that children significantly improved in almost all the spatial aspects considered, while the control group didn't show any improvement. These results confirm that perceptual development in the case of blindness can be enhanced with naturally associated auditory feedbacks to body movements. Therefore the early introduction of a tailored audio-motor training could potentially prevent spatial developmental delays in visually impaired children.