From science to technology: Orientation and mobility in blind children and adults

A Technology System to Help People With Intellectual Disability and Blindness Find Room Destinations During Indoor Traveling: Case Series Study

BACKGROUND

People with severe or profound intellectual disability and visual impairment tend to have serious problems in orientation and mobility and need assistance for their indoor traveling. The use of technology solutions may be critically important to help them curb those problems and achieve a level of independence.

OBJECTIVE

This study aimed to assess a new technology system to help people with severe to profound intellectual disability and blindness find room destinations during indoor traveling.

METHODS

A total of 7 adults were included in the study. The technology system entailed a barcode reader, a series of barcodes marking the room entrances, a smartphone, and a special app that controlled the presentation of different messages (instructions) for the participants. The messages varied depending on whether the participants were (1) in an area between room entrances, (2) in correspondence with a room entrance to bypass, or (3) in correspondence with a room entrance representing the destination to enter. The intervention with the technology system was implemented according to a nonconcurrent multiple baseline design across participants. Sessions included 7 traveling trials, in each of which the participants were to reach and enter a specific room (1 of the 7 or 9 available) to deliver an object they had carried (transported) during their traveling.

RESULTS

The participants' mean frequency of traveling trials completed correctly was between zero and 2 per session during the baseline (without the system). Their mean frequency increased to between about 6 and nearly 7 per session during the intervention (with the system).

CONCLUSIONS

The findings suggest that the new technology system might be a useful support tool for people with severe to profound intellectual disability and blindness.

Benefits and challenges of using assistive technology in the education and rehabilitation of Individuals with visual impairments

PURPOSE

Individuals with visual impairments use assistive technology in various aspects of life. Professionals who work with visually impaired people need to know about assistive technologies. The purpose of this study was to analyse the benefits and challenges of assistive technologies by assessing the degree of satisfaction with assistive technologies in different life situations expressed both by users and by professionals.

MATERIALS AND METHODS

Data were collected from 36 individuals with visual impairments and 27 professionals using online questionnaires. Further information was obtained from five individuals with visual impairments through focus group interviews.

RESULTS

The results show that 26 (72.2%) individuals with visual impairments and almost all professionals (N = 25; 92.6%) acknowledge the benefits of using assistive technology. They recognise the importance of assistive technology in independent living for individuals with visual impairments. However, 27 (75%) individuals with visual impairment and 26 (96.3%) professionals consider financial constraints to be the biggest problem.

CONCLUSION

More cost-effective technologies need to be developed, and social policies and opportunities created so that every individual with visual impairment can obtain assistive technologies that meet their needs. This would increase the independence of individuals with visual impairments in all areas of life.

Postural control depends on early visual experience

The present study investigated the role of early visual experience in the development of postural control (balance) and locomotion (gait). In a cross-sectional design, balance and gait were assessed in 59 participants (ages 7-43 years) with a history of (a) transient congenital blindness, (b) transient late-onset blindness, (c) permanent congenitally blindness, or (d) permanent late-onset blindness, as well as in normally sighted controls. Cataract-reversal participants who experienced a transient phase of blindness and gained sight through cataract removal surgery showed worse balance performance compared with sighted controls even when tested with eyes closed. Individuals with reversed congenital cataracts performed worse than individuals with reversed developmental (late emerging) cataracts. Balance performance in congenitally cataract-reversal participants when tested with eyes closed was not significantly different from that in permanently blind participants. In contrast, their gait parameters did not differ significantly from those of sighted controls. The present findings highlight both the need for visual calibration of proprioceptive and vestibular systems and the crossmodal adaptability of locomotor functions.

Learning and navigating digitally rendered haptic spatial layouts

Learning spatial layouts and navigating through them rely not simply on sight but rather on multisensory processes, including touch. Digital haptics based on ultrasounds are effective for creating and manipulating mental images of individual objects in sighted and visually impaired participants. Here, we tested if this extends to scenes and navigation within them. Using only tactile stimuli conveyed via ultrasonic feedback on a digital touchscreen (i.e., a digital interactive map), 25 sighted, blindfolded participants first learned the basic layout of an apartment based on digital haptics only and then one of two trajectories through it. While still blindfolded, participants successfully reconstructed the haptically learned 2D spaces and navigated these spaces. Digital haptics were thus an effective means to learn and translate, on the one hand, 2D images into 3D reconstructions of layouts and, on the other hand, navigate actions within real spaces. Digital haptics based on ultrasounds represent an alternative learning tool for complex scenes as well as for successful navigation in previously unfamiliar layouts, which can likely be further applied in the rehabilitation of spatial functions and mitigation of visual impairments.

An investigation into the effectiveness of using acoustic touch to assist people who are blind

Wearable smart glasses are an emerging technology gaining popularity in the assistive technologies industry. Smart glasses aids typically leverage computer vision and other sensory information to translate the wearer's surrounding into computer-synthesized speech. In this work, we explored the potential of a new technique known as "acoustic touch" to provide a wearable spatial audio solution for assisting people who are blind in finding objects. In contrast to traditional systems, this technique uses smart glasses to sonify objects into distinct sound auditory icons when the object enters the device's field of view. We developed a wearable Foveated Audio Device to study the efficacy and usability of using acoustic touch to search, memorize, and reach items. Our evaluation study involved 14 participants, 7 blind or low-visioned and 7 blindfolded sighted (as a control group) participants. We compared the wearable device to two idealized conditions, a verbal clock face description and a sequential audio presentation through external speakers. We found that the wearable device can effectively aid the recognition and reaching of an object. We also observed that the device does not significantly increase the user's cognitive workload. These promising results suggest that acoustic touch can provide a wearable and effective method of sensory augmentation.

A novel multisensory device for the assessment and rehabilitation of perceptual and attentional competencies

The present study aims to assess a novel technological device suitable for investigating perceptual and attentional competencies in people with or without sensory impairment. The TechPAD is a cabled system including embedded sensors and actuators to enable visual, auditory, and tactile interactions and a capacitive surface receiving inputs from the user. The system is conceived to create multisensory environments, using multiple units controlled separately and simultaneously. We assessed the device by adapting a spatial attention task comparing performances in different cognitive load conditions (high or low) and stimulation (unimodal, bimodal, or trimodal). 28 sighted adults were asked to monitor both the central and peripheral parts of the device and to tap a target stimulus (either visual, auditory, haptic, or multimodal) as fast as they could. Our results suggest that this new device can provide congruent and incongruent multimodal stimuli and quantitatively measure parameters such as reaction time and accuracy, allowing to investigate perceptual mechanisms in multisensory environments.Clinical Relevance-The TechPad is a reliable tool for the assessment of spatial attention during interactive tasks. its application in clinical trials will pave the way to its role in multisensory rehabilitation.

Virtual reality as a means to explore assistive technologies for the visually impaired

Visual impairment represents a significant health and economic burden affecting 596 million globally. The incidence of visual impairment is expected to double by 2050 as our population ages. Independent navigation is challenging for persons with visual impairment, as they often rely on non-visual sensory signals to find the optimal route. In this context, electronic travel aids are promising solutions that can be used for obstacle detection and/or route guidance. However, electronic travel aids have limitations such as low uptake and limited training that restrict their widespread use. Here, we present a virtual reality platform for testing, refining, and training with electronic travel aids. We demonstrate the viability on an electronic travel aid developed in-house, consist of a wearable haptic feedback device. We designed an experiment in which participants donned the electronic travel aid and performed a virtual task while experiencing a simulation of three different visual impairments: age-related macular degeneration, diabetic retinopathy, and glaucoma. Our experiments indicate that our electronic travel aid significantly improves the completion time for all the three visual impairments and reduces the number of collisions for diabetic retinopathy and glaucoma. Overall, the combination of virtual reality and electronic travel aid may have a beneficial role on mobility rehabilitation of persons with visual impairment, by allowing early-phase testing of electronic travel aid prototypes in safe, realistic, and controllable settings.

Concussion through my eyes: a qualitative study exploring concussion experiences and perceptions of male English blind footballers

OBJECTIVES

Athletes with impairments play sports with a risk of sustaining head injuries and concussions. However, the scientific knowledge needed to improve care is lacking. This qualitative study explores English blind 5-a-side footballers' perceptions of concussion, concussion risks and prevention to improve para concussion care.

METHODS

Nine semi-structured interviews were conducted with male English blind footballers (six current and three retired). Data were analysed by thematic analysis using a six-stage approach.

RESULTS

Blind footballers were not sure about the number of concussions they had sustained. They lacked an understanding of what to experience when concussed, and they perceived the diagnosis and experience of a concussion to be different for a person without vision. Perceived concussion severity and previous concussion experiences were key concepts affecting their concussion reporting behaviours. Participants mentioned spatial orientation and sleep are important to function in daily life and were affected by concussions. However, these factors are not adequately included in current assessment tools or clinical guidance for sports-related concussions.

CONCLUSION

Blind footballers suggested the quality and accuracy of reported concussions were impacted by lack of concussion experience, knowledge and concomitant impairment. A better understanding of concussion symptoms and injury mechanisms will improve concussion reporting for athletes with visual impairments. These athlete insights should guide future studies and para sports governing body initiatives to improve concussion reporting, diagnosis and management in para athletes.

Technology-Aided Spatial Cues, Instructions, and Preferred Stimulation for Supporting People With Intellectual and Visual Disabilities in Their Occupational Engagement and Mobility: Usability Study

Background

Persons with severe or profound intellectual disability and visual impairment tend to be passive and sedentary, and technology-aided intervention may be required to improve their condition without excessive demands on staff time.

Objective

This study aims to extend the assessment of technology-aided interventions for supporting functional occupational engagement and mobility in 7 people with intellectual disability and visual impairment and to use a technology system that is simpler and less expensive than those previously used.

Methods

The technology system involved a Samsung Galaxy A10, 4 Philips Hue indoor motion sensors, and 4 mini speakers. Within each session, the participants were to collect 18 objects (ie, one at a time) from 3 different areas (stations) located within a large room, bring each of the objects to a central desk, and put away each of those objects there. For each object, the participants received verbal (spatial) cues for guiding them to the area where the object was to be collected, a verbal instruction (ie, request) to take an object, verbal (spatial) cues for guiding them to the central desk, a verbal instruction to put away the object collected, and praise and preferred stimulation.

Results

During baseline, the frequency of responses completed correctly (objects collected and put away independently) was 0 or near 0. During the intervention phase (ie, with the support of the technology setup), the frequency increased for all participants, reaching a mean of almost 18 (out of 18 response opportunities) for 6 participants and about 13 for the remaining participant. The mean session duration ranged from 12 to 30 minutes.

Conclusions

A program, such as the one used in this study, can be useful in promoting occupational engagement and mobility in persons with intellectual disability and visual impairment.

Geometry intuitions without vision? A study in blind children and adults

Geometry intuitions seem to be rooted in a non-verbal system that humans possess since early age. However, the mechanisms underlying the comprehension of basic geometric concepts remain elusive. Some authors have suggested that the starting point of geometry development could be found in the visual perception of specific features in our environment, thus conferring to vision a foundational role in the acquisition of geometric skills. To examine this assumption, a test probing intuitive understanding of basic geometric concepts was presented to congenitally blind children and adults. Participants had to detect the intruder among four different shapes, from which three instantiated a specific geometrical concept and one (the intruder) violated it. Although they performed above the chance level, the blind presented poorer performance than the sighted participants who did the task in the visual modality (i.e., with the eyes open), but performed equally well than the sighted who did the task in the tactile modality (i.e., with a blindfold). We therefore provide evidence that geometric abilities are impacted by the lack of vision.

A Proposal of a Motion Measurement System to Support Visually Impaired People in Rehabilitation Using Low-Cost Inertial Sensors

The rehabilitation of a visually impaired person (VIP) is a systematic process where the person is provided with tools that allow them to deal with the impairment to achieve personal autonomy and independence, such as training for the use of the long cane as a tool for orientation and mobility (O&M). This process must be trained personally by specialists, leading to a limitation of human, technological and structural resources in some regions, especially those with economical narrow circumstances. A system to obtain information about the motion of the long cane and the leg using low-cost inertial sensors was developed to provide an overview of quantitative parameters such as sweeping coverage and gait analysis, that are currently visually analyzed during rehabilitation. The system was tested with 10 blindfolded volunteers in laboratory conditions following constant contact, two points touch, and three points touch travel techniques. The results indicate that the quantification system is reliable for measuring grip rotation, safety zone, sweeping amplitude and hand position using orientation angles with an accuracy of around 97.62%. However, a new method or an improvement of hardware must be developed to improve gait parameters’ measurements, since the step length measurement presented a mean accuracy of 94.62%. The system requires further development to be used as an aid in the rehabilitation process of the VIP. Now, it is a simple and low-cost technological aid that has the potential to improve the current practice of O&M.

Analysis and Validation of Cross-Modal Generative Adversarial Network for Sensory Substitution

Visual-auditory sensory substitution has demonstrated great potential to help visually impaired and blind groups to recognize objects and to perform basic navigational tasks. However, the high latency between visual information acquisition and auditory transduction may contribute to the lack of the successful adoption of such aid technologies in the blind community; thus far, substitution methods have remained only laboratory-scale research or pilot demonstrations. This high latency for data conversion leads to challenges in perceiving fast-moving objects or rapid environmental changes. To reduce this latency, prior analysis of auditory sensitivity is necessary. However, existing auditory sensitivity analyses are subjective because they were conducted using human behavioral analysis. Therefore, in this study, we propose a cross-modal generative adversarial network-based evaluation method to find an optimal auditory sensitivity to reduce transmission latency in visual-auditory sensory substitution, which is related to the perception of visual information. We further conducted a human-based assessment to evaluate the effectiveness of the proposed model-based analysis in human behavioral experiments. We conducted experiments with three participant groups, including sighted users (SU), congenitally blind (CB) and late-blind (LB) individuals. Experimental results from the proposed model showed that the temporal length of the auditory signal for sensory substitution could be reduced by 50%. This result indicates the possibility of improving the performance of the conventional vOICe method by up to two times. We confirmed that our experimental results are consistent with human assessment through behavioral experiments. Analyzing auditory sensitivity with deep learning models has the potential to improve the efficiency of sensory substitution.

Echolocation as a Means for People with Visual Impairment (PVI) to Acquire Spatial Knowledge of Virtual Space

In virtual environments, spatial information is communicated visually. This prevents people with visual impairment (PVI) from accessing such spaces. In this article, we investigate whether echolocation could be used as a tool to convey spatial information by answering the following research questions: What features of virtual space can be perceived by PVI through the use of echolocation? How does active echolocation support PVI in acquiring spatial knowledge of a virtual space? And what are PVI’s opinions regarding the use of echolocation to acquire landmark and survey knowledge of virtual space? To answer these questions, we conducted a two-part within-subjects experiment with 12 people who were blind or had a visual impairment and found that size and materials of rooms and 90-degree turns were detectable through echolocation, participants preferred using echoes derived from footsteps rather than from artificial sound pulses, and echolocation supported the acquisition of mental maps of a virtual space. Ultimately, we propose that appropriately designed echolocation in virtual environments improves understanding of spatial information and access to digital games for PVI.

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.

O&M Indoor Virtual Environments for People Who Are Blind

BACKGROUND: Knowing their current position in the surroundings constitutes one of the biggest challenges faced by people with visual disabilities when they move around. For them, it is difficult to be aware of the direction in which they are going, and the location of nearby objects and obstacles. In this context, obtaining relevant spatial information is always very significant to these individuals. Hence, the research in the development of assistive technologies for needs and perspectives of people who are blind has been a promising area in terms of the orientation and mobility (O&M) challenges.

OBJECTIVE: The purpose of this study is to systematically examine the literature on &M virtual environments designed to support indoor navigation to identify techniques for both developing and evaluating the usability and cognitive impact of these applications.

METHODS: A systematic literature review (SLR) was performed, considering population, intervention, outcomes, and study design as eligibility criteria. After a filtering process from 987 works retrieved from six databases, we extracted data from 51 papers, which meet the study selection criteria.

RESULTS: The analysis of the 51 papers describing 31 O&M indoor virtual environments, indicated that O&M virtual environments to support indoor navigation are usually designed for desktop, adopt spatial audio as way to support orientation, and use joystick as primary interaction device. Regarding evaluation techniques, questionnaires, interviews, user observation, and performance logs are commonly used to evaluate usability in this context. In tests involving users, the participants are usually adults aged 21–59 years, who individually spend about 90 minutes split in usually two evaluation sessions. Most papers do not report any strategies to evaluate the cognitive impact of O&M virtual environments on users’ navigational and wayfinding skills. Thirteen papers (25.49%) reported the conduction of experiments or quasi-experiments and demonstrated pieces of evidence associated with a positive cognitive impact resultant from O&M indoor virtual environments usage. Finally, only four papers (7.84%) reported the development of indoor maps editors for O&M virtual environments.

CONCLUSION: Our SLR summarizes the characteristics of 32 O&M virtual environments. It compiles state-of-the-art for indoor simulations in this domain and highlights their challenges and impacts in O&M training. Also, the absence of clear guidelines to design and evaluate O&M virtual environments and the few available computer editors of indoor maps appear as research opportunities.

Use of technology by orientation and mobility professionals in Australia and Malaysia before COVID-19

PURPOSE

Orientation and Mobility (O&M) professionals teach people with low vision or blindness to use specialist assistive technologies to support confident travel, but many O&M clients now prefer a smartphone. This study aimed to investigate what technology O&M professionals in Australia and Malaysia have, use, like, and want to support their client work, to inform the development of O&M technologies and build capacity in the international O&M profession.

MATERIALS AND METHODS

A technology survey was completed by professionals (n = 36) attending O&M workshops in Malaysia. A revised survey was completed online by O&M specialists (n = 31) primarily in Australia. Qualitative data about technology use came from conferences, workshops and interviews with O&M professionals. Descriptive statistics were analysed together with free-text data.

RESULTS

Limited awareness of apps used by clients, unaffordability of devices, and inadequate technology training discouraged many O&M professionals from employing existing technologies in client programmes or for broader professional purposes. Professionals needed to learn smartphone accessibility features and travel-related apps, and ways to use technology during O&M client programmes, initial professional training, ongoing professional development and research.

CONCLUSIONS

Smartphones are now integral to travel with low vision or blindness and early-adopter O&M clients are the travel tech-experts. O&M professionals need better initial training and then regular upskilling in mainstream O&M technologies to expand clients' travel choices. COVID-19 has created an imperative for technology laggards to upskill for O&M tele-practice. O&M technology could support comprehensive O&M specialist training and practice in Malaysia, to better serve O&M clients with complex needs.Implications for rehabilitationMost orientation and mobility (O&M) clients are travelling with a smartphone, so O&M specialists need to be abreast of mainstream technologies, accessibility features and apps used by clients for orientation, mobility, visual efficiency and social engagement.O&M specialists who are technology laggards need human-guided support to develop confidence in using travel technologies, and O&M clients are the experts. COVID-19 has created an imperative to learn skills for O&M tele-practice.Affordability is a significant barrier to O&M professionals and clients accessing specialist travel technologies in Malaysia, and to O&M professionals upgrading technology in Australia.Comprehensive training for O&M specialists is needed in Malaysia to meet the travel needs of clients with low vision or blindness who also have physical, cognitive, sensory or mental health complications.

Aesthetics and the perceived stigma of assistive technology for visual impairment

Purpose: The aim of this study was to identify factors that influence the perceived stigma of two assistive devices for visual impairment, namely the white cane and smart glasses.Method: Face-to-face semi-structured interviews with eight European students were conducted to probe their experiences and knowledge related to disability, assistive technology, visual impairment, as well as handheld and wearable devices.Results: Close relationships with disabled people seems to have a positive influence on participants perceptions about stigma, disability, and assistive technology. Academic background seems to not have any influence. The aesthetics of assistive devices was observed as an important factor that influences the adoption or abandonment of the device.Conclusion: Device without negative symbolism but with modern aesthetics (smart glasses) were positively accepted by the participants than the device with traditional aesthetics and symbolisms of visual impairment (white cane). Designers should, therefore, consider aesthetics in addition to functionality in order to avoid the perceived stigma, thereby reducing the chances of device abandonment.IMPLICATIONS FOR REHABILITATIONUnderstanding the factors that influence the perceived stigma associated with assistive technology can help designers and developers to reduce assistive technology abandonment and perceived stigma.Designers need to consider both functionality and aesthetics. While functionality is crucial for the users' adaptation, aesthetics is important for the users' positive perceptions.

Audomni: Super-Scale Sensory Supplementation to Increase the Mobility of Blind and Low-Vision Individuals-A Pilot Study

OBJECTIVE

Blindness and low vision have severe effects on individuals' quality of life and socioeconomic cost; a main contributor of which is a prevalent and acutely decreased mobility level. To alleviate this, numerous technological solutions have been proposed in the last 70 years; however, none has become widespread.

METHOD

In this paper, we introduce the vision-to-audio, super-scale sensory substitution/supplementation device Audomni; we address the field-encompassing issues of ill-motivated and overabundant test methodologies and metrics; and we utilize our proposed Desire of Use model to evaluate proposed pilot user tests, their results, and Audomni itself.

RESULTS

Audomni holds a spatial resolution of 80 x 60 pixels at ~1.2° angular resolution and close to real-time temporal resolution, outdoor-viable technology, and several novel differentiation methods. The tests indicated that Audomni has a low learning curve, and several key mobility subtasks were accomplished; however, the tests would benefit from higher real-life motivation and data collection affordability.

CONCLUSION

Audomni shows promise to be a viable mobility device - with some addressable issues. Employing Desire of Use to design future tests should provide both high real-life motivation and relevance to them.

SIGNIFICANCE

As far as we know, Audomni features the greatest information conveyance rate in the field, yet seems to offer comprehensible and fairly intuitive sonification; this work is also the first to utilize Desire of Use as a tool to evaluate user tests, a device, and to lay out an overarching project aim.

Desire of Use: A Hierarchical Decomposition of Activities and its Application on Mobility of Blind and Low-Vision Individuals

OBJECTIVE

Blind and low-vision individuals often have severely reduced mobility, affecting their quality of life and associated socioeconomic cost. Despite numerous efforts and great technological progress, the only used primary mobility aids are still white canes and seeing-eye dogs. Furthermore, there is a permeating tendency in the field to ignore knowledge of both mobility and the target group, as well as constantly design new metrics and tests that makes comparisons between solutions markedly more difficult.

METHOD

The Desire of Use model is introduced in an effort to promote a more holistic approach; it should be generalizable for any activity by any user, but is here applied on mobility of blind and low-vision individuals by a proposal and integration of parameters.

RESULTS

An embodiment of the model is presented and with it we show why popular mobility metrics of today are insufficient to guide design; what tasks and metrics that should provide better understanding; as well as which fundamental properties determine them and are critical to discuss.

CONCLUSION

Desire of Use has been introduced as a tool and a theoretical framework, and a realization has been proposed.

SIGNIFICANCE

Desire of Use offers both a structured perspective of pertinent design challenges facing a given solution, as well as a platform from which to compare test results and properties of existing solutions; in for example the field of electronic travel aids it should prove valuable for designing and evaluating new tests and devices.

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.

Spatial Representation of the Workspace in Blind, Low Vision, and Sighted Human Participants

It has been proposed that haptic spatial perception depends on one's visual abilities. We tested spatial perception in the workspace using a combination of haptic matching and line drawing tasks. There were 132 participants with varying degrees of visual ability ranging from congenitally blind to normally sighted. Each participant was blindfolded and asked to match a haptic target position felt under a table with their nondominant hand using a pen in their dominant hand. Once the pen was in position on the tabletop, they had to draw a line of equal length to a previously felt reference object by moving the pen laterally. We used targets at three different locations to evaluate whether different starting positions relative to the body give rise to different matching errors, drawn line lengths, or drawn line angles. We found no influence of visual ability on matching error, drawn line length, or line angle, but we found that early-blind participants are slightly less consistent in their matching errors across space. We conclude that the elementary haptic abilities tested in these tasks do not depend on visual experience.

Neuromorphic Vibrotactile Stimulation of Fingertips for Encoding Object Stiffness in Telepresence Sensory Substitution and Augmentation Applications

We present a tactile telepresence system for real-time transmission of information about object stiffness to the human fingertips. Experimental tests were performed across two laboratories (Italy and Ireland). In the Italian laboratory, a mechatronic sensing platform indented different rubber samples. Information about rubber stiffness was converted into on-off events using a neuronal spiking model and sent to a vibrotactile glove in the Irish laboratory. Participants discriminated the variation of the stiffness of stimuli according to a two-alternative forced choice protocol. Stiffness discrimination was based on the variation of the temporal pattern of spikes generated during the indentation of the rubber samples. The results suggest that vibrotactile stimulation can effectively simulate surface stiffness when using neuronal spiking models to trigger vibrations in the haptic interface. Specifically, fractional variations of stiffness down to 0.67 were significantly discriminated with the developed neuromorphic haptic interface. This is a performance comparable, though slightly worse, to the threshold obtained in a benchmark experiment evaluating the same set of stimuli naturally with the own hand. Our paper presents a bioinspired method for delivering sensory feedback about object properties to human skin based on contingency-mimetic neuronal models, and can be useful for the design of high performance haptic devices.

Audio Motor Training at the Foot Level Improves Space Representation

Spatial representation is developed thanks to the integration of visual signals with the other senses. It has been shown that the lack of vision compromises the development of some spatial representations. In this study we tested the effect of a new rehabilitation device called ABBI (Audio Bracelet for Blind Interaction) to improve space representation. ABBI produces an audio feedback linked to body movement. Previous studies from our group showed that this device improves the spatial representation of space in early blind adults around the upper part of the body. Here we evaluate whether the audio motor feedback produced by ABBI can also improve audio spatial representation of sighted individuals in the space around the legs. Forty five blindfolded sighted subjects participated in the study, subdivided into three experimental groups. An audio space localization (front-back discrimination) task was performed twice by all groups of subjects before and after different kind of training conditions. A group (experimental) performed an audio-motor training with the ABBI device placed on their foot. Another group (control) performed a free motor activity without audio feedback associated with body movement. The other group (control) passively listened to the ABBI sound moved at foot level by the experimenter without producing any body movement. Results showed that only the experimental group, which performed the training with the audio-motor feedback, showed an improvement in accuracy for sound discrimination. No improvement was observed for the two control groups. These findings suggest that the audio-motor training with ABBI improves audio space perception also in the space around the legs in sighted individuals. This result provides important inputs for the rehabilitation of the space representations in the lower part of the body.

The Effect of Visual Experience on Perceived Haptic Verticality When Tilted in the Roll Plane

The orientation of the body in space can influence perception of verticality leading sometimes to biases consistent with priors peaked at the most common head and body orientation, that is upright. In this study, we investigate haptic perception of verticality in sighted individuals and early and late blind adults when tilted counterclockwise in the roll plane. Participants were asked to perform a stimulus orientation discrimination task with their body tilted to their left ear side 90° relative to gravity. Stimuli were presented by using a motorized haptic bar. In order to test whether different reference frames relative to the head influenced perception of verticality, we varied the position of the stimulus on the body longitudinal axis. Depending on the stimulus position sighted participants tended to have biases away or toward their body tilt. Visually impaired individuals instead show a different pattern of verticality estimations. A bias toward head and body tilt (i.e., Aubert effect) was observed in late blind individuals. Interestingly, no strong biases were observed in early blind individuals. Overall, these results posit visual sensory information to be fundamental in influencing the haptic readout of proprioceptive and vestibular information about body orientation relative to gravity. The acquisition of an idiotropic vector signaling the upright might take place through vision during development. Regarding early blind individuals, independent spatial navigation experience likely enhanced by echolocation behavior might have a role in such acquisition. In the case of participants with late onset blindness, early experience of vision might lead them to anchor their visually acquired priors to the haptic modality with no disambiguation between head and body references as observed in sighted individuals (Fraser et al., 2015). With our study, we aim to investigate haptic perception of gravity direction in unusual body tilts when vision is absent due to visual impairment. Insofar, our findings throw light on the influence of proprioceptive/vestibular sensory information on haptic perceived verticality in blind individuals showing how this phenomenon is affected by visual experience.

Sensory augmentation: integration of an auditory compass signal into human perception of space

Bio-mimetic approaches to restoring sensory function show great promise in that they rapidly produce perceptual experience, but have the disadvantage of being invasive. In contrast, sensory substitution approaches are non-invasive, but may lead to cognitive rather than perceptual experience. Here we introduce a new non-invasive approach that leads to fast and truly perceptual experience like bio-mimetic techniques. Instead of building on existing circuits at the neural level as done in bio-mimetics, we piggy-back on sensorimotor contingencies at the stimulus level. We convey head orientation to geomagnetic North, a reliable spatial relation not normally sensed by humans, by mimicking sensorimotor contingencies of distal sounds via head-related transfer functions. We demonstrate rapid and long-lasting integration into the perception of self-rotation. Short training with amplified or reduced rotation gain in the magnetic signal can expand or compress the perceived extent of vestibular self-rotation, even with the magnetic signal absent in the test. We argue that it is the reliability of the magnetic signal that allows vestibular spatial recalibration, and the coding scheme mimicking sensorimotor contingencies of distal sounds that permits fast integration. Hence we propose that contingency-mimetic feedback has great potential for creating sensory augmentation devices that achieve fast and genuinely perceptual experiences.

Prior Visual Experience Modulates Learning of Sound Localization Among Blind Individuals

Cross-modal learning requires the use of information from different sensory modalities. This study investigated how the prior visual experience of late blind individuals could modulate neural processes associated with learning of sound localization. Learning was realized by standardized training on sound localization processing, and experience was investigated by comparing brain activations elicited from a sound localization task in individuals with (late blind, LB) and without (early blind, EB) prior visual experience. After the training, EB showed decreased activation in the precuneus, which was functionally connected to a limbic-multisensory network. In contrast, LB showed the increased activation of the precuneus. A subgroup of LB participants who demonstrated higher visuospatial working memory capabilities (LB-HVM) exhibited an enhanced precuneus-lingual gyrus network. This differential connectivity suggests that visuospatial working memory due to the prior visual experience gained via LB-HVM enhanced learning of sound localization. Active visuospatial navigation processes could have occurred in LB-HVM compared to the retrieval of previously bound information from long-term memory for EB. The precuneus appears to play a crucial role in learning of sound localization, disregarding prior visual experience. Prior visual experience, however, could enhance cross-modal learning by extending binding to the integration of unprocessed information, mediated by the cognitive functions that these experiences develop.