Spatial representation and visual impairement - Developmental trends and new technological tools for assessment and rehabilitation

It is well known that perception is mediated by the five sensory modalities (sight, hearing, touch, smell and taste), which allows us to explore the world and build a coherent spatio-temporal representation of the surrounding environment. Typically, our brain collects and integrates coherent information from all the senses to build a reliable spatial representation of the world. In this sense, perception emerges from the individual activity of distinct sensory modalities, operating as separate modules, but rather from multisensory integration processes. The interaction occurs whenever inputs from the senses are coherent in time and space (Eimer, 2004). Therefore, spatial perception emerges from the contribution of unisensory and multisensory information, with a predominant role of visual information for space processing during the first years of life. Despite a growing body of research indicates that visual experience is essential to develop spatial abilities, to date very little is known about the mechanisms underpinning spatial development when the visual input is impoverished (low vision) or missing (blindness). The thesis's main aim is to increase knowledge about the impact of visual deprivation on spatial development and consolidation and to evaluate the effects of novel technological systems to quantitatively improve perceptual and cognitive spatial abilities in case of visual impairments. Chapter 1 summarizes the main research findings related to the role of vision and multisensory experience on spatial development. Overall, such findings indicate that visual experience facilitates the acquisition of allocentric spatial capabilities, namely perceiving space according to a perspective different from our body. Therefore, it might be stated that the sense of sight allows a more comprehensive representation of spatial information since it is based on environmental landmarks that are independent of body perspective. Chapter 2 presents original studies carried out by me as a Ph.D. student to investigate the developmental mechanisms underpinning spatial development and compare the spatial performance of individuals with affected and typical visual experience, respectively visually impaired and sighted. Overall, these studies suggest that vision facilitates the spatial representation of the environment by conveying the most reliable spatial reference, i.e., allocentric coordinates. However, when visual feedback is permanently or temporarily absent, as in the case of congenital blindness or blindfolded individuals, respectively, compensatory mechanisms might support the refinement of haptic and auditory spatial coding abilities. The studies presented in this chapter will validate novel experimental paradigms to assess the role of haptic and auditory experience on spatial representation based on external (i.e., allocentric) frames of reference. Chapter 3 describes the validation process of new technological systems based on unisensory and multisensory stimulation, designed to rehabilitate spatial capabilities in case of visual impairment. Overall, the technological validation of new devices will provide the opportunity to develop an interactive platform to rehabilitate spatial impairments following visual deprivation. Finally, Chapter 4 summarizes the findings reported in the previous Chapters, focusing the attention on the consequences of visual impairment on the developmental of unisensory and multisensory spatial experience in visually impaired children and adults compared to sighted peers. It also wants to highlight the potential role of novel experimental tools to validate the use to assess spatial competencies in response to unisensory and multisensory events and train residual sensory modalities under a multisensory rehabilitation

THE SOUND OF SCOTOMA: A multisensory integration approach for individuals with Macular Degeneration

openAudio-spatial representation reorganizes in the absence of visual inputs, as in the case of blind individuals. However, it is not clear how this spatial reorganization works. Although blindness is an ideal condition to understand how other sensory modalities react in absence of vision, there are some limits in using it as a modal. The main limit is that blindness can be considered a stable model of cortical organization and it does not allow to understand the mechanisms which cause this reorganization. To understand this process, we have studied a unique group of individuals suffering from Macular Degeneration (MD) for whom loss of visual inputs due to a progressive scotoma is an ongoing process. In this dissertation I decided to focus on understanding auditory spatial representation in MD individuals and to develop technnological solutions for them incorporating multisensory integration. First, we developed a device called ARENA which is an audio-tactile matrix of speakers to study audio-spatial localization in MD individuals. Our findings show that visual loss brings an immediate change in the processing of audio-spatial percept by attracting the lateral sounds towards scotoma positions in the center, producing a strong auditory spatial perception bias. To recaliberate this audio-spatial bias and to give MD individuals an understanding of their own scotoma to develop an effective pseudo fovea, we have designed a rehabilitation protocol called Intelligent Audio Visual Thumble Training (IVATT). A multisensory feedback device Audio Visual Thumble (AVT) is developed for this training. Our findings show that this technique is effective to overcome the audio-spatial bias and can improve the precision towards visual stimuli in peripheral visual field. This work concludes that development of scotoma alters the audio-spatial representation and hence focus of rehabilitation techniques can be extended to bring-in multisensory modalities in order to utilize residual vision of MD individuals.embargoed_20210317XXXII CICLO - BIOINGEGNERIA E ROBOTICA - BIOENGINEERING AND ROBOTICS - Cognitive robotics, interaction and rehabilitation technologies09/C2 - FISICA TECNICA E INGEGNERIA NUCLEAREAhmad, Hafsa

Literature Review: Orientation and Mobility Assistive Technology for Students with Visual Impairment

The development of increasingly sophisticated technology is accompanied by the discovery of new assistive devices that should be accessible to all people, including the blind in order to maintain or improve functions so as to improve welfare. This study uses a literature review method with descriptive analysis by analyzing 20 articles. The purpose of this research is to examine more related to assistive technology for the blind in navigating indoors and outdoors including buildings and the accessibility of public services. The literature search was carried out through an electronic search for publications from ERIC, Researchgate, Spingerlink, Sage, Science Direct, Google Scholar and IEEE Xplore. The results of the study describe the use of various assistive technologies for the visually impaired related to navigation in spaces or buildings and even the wider environment as well as public services that are commonly accessed by the public. Furthermore, it is related to the existence of a brief description of the assistive technology developed and the benefits of the results of the development for users

Opportunities for Supporting Self-efficacy through Orientation & Mobility Training Technologies for Blind and Partially Sighted People

Orientation and mobility (O&M) training provides essential skills and techniques for safe and independent mobility for blind and partially sighted (BPS) people. The demand for O&M training is increasing as the number of people living with vision impairment increases. Despite the growing portfolio of HCI research on assistive technologies (AT), few studies have examined the experiences of BPS people during O&M training, including the use of technology to aid O&M training. To address this gap, we conducted semi-structured interviews with 20 BPS people and 8 Mobility and Orientation Trainers (MOT). The interviews were thematically analysed and organised into four overarching themes discussing factors influencing the self-efficacy belief of BPS people: Tools and Strategies for O&M training, Technology Use in O&M Training, Changing Personal and Social Circumstances, and Social Influences. We further highlight opportunities for combinations of multimodal technologies to increase access to and effectiveness of O&M training