1,720,961 research outputs found
Allocentric spatial perception through vision and touch in sighted and blind children
No full textVision 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
Effects of increasing stimulated area in spatiotemporally congruent unisensory and multisensory conditions
No full textResearch 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
Shape recognition with sounds: Improvement in sighted individuals after audio-motor training
No full textRecent 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
No full textSeveral 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
A Novel Wearable and Wireless Device to Investigate Perception in Interactive Scenarios
No full textThe aim of the present work is to introduce a novel wearable device suitable to be used to investigate perception in interactive tasks, on individuals with and without sensory disabilities. The system is composed by small units embedded with sensors and actuators that allows emitting different kind of stimuli (light, haptic, sound) and to record the user response, thanks to a capacitive sensor. We validated the system by implementing an interception task in three different sensory modalities: visual, tactile and auditory. Six subjects with normal sight were asked to tap either a static or a moving stimulus generated by 6 units placed on their forearm. Results suggest that the system can effectively provide new insights in characterizing how perception principles vary when perceptual judgement occurs through different senses. This confirms the device potential in contributing to the design of rehabilitation protocols rooted on neuroscientific findings, for people with sensory impairments
Effects of audio-motor training on spatial representations in long-term late blindness
No full textVision 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
Clinical assessment of the TechArm system on visually impaired and blind children during uni- and multi-sensory perception tasks
No full textWe 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
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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