Absence Of Visual Information Research Articles

Visual Deprivation's Impact on Dynamic Posture Control of Trunk: A Comprehensive Sensing Information Analysis of Neurophysiological Mechanisms.

Visual information affects static postural control, but how it affects dynamic postural control still needs to be fully understood. This study investigated the effect of proprioception weighting, influenced by the presence or absence of visual information, on dynamic posture control during voluntary trunk movements. We recorded trunk movement angle and angular velocity, center of pressure (COP), electromyographic, and electroencephalography signals from 35 healthy young adults performing a standing trunk flexion-extension task under two conditions (Vision and No-Vision). A random forest analysis identified the 10 most important variables for classifying the conditions, followed by a Wilcoxon signed-rank test. The results showed lower maximum forward COP displacement and trunk flexion angle, and faster maximum flexion angular velocity in the No-Vision condition. Additionally, the alpha/beta ratio of the POz during the switch phase was higher in the No-Vision condition. These findings suggest that visual deprivation affects cognitive- and sensory-integration-related brain regions during movement phases, indicating that sensory re-weighting due to visual deprivation impacts motor control. The effects of visual deprivation on motor control may be used for evaluation and therapeutic interventions in the future.

Autobiographical memory of blind and sighted early teenagers: Memory accessibility, episodicity and phenomenology

AbstractVisual system is crucial to autobiographical memory. Research tended to show that blind adults may compensate for the loss of visual information in retrieval of their autobiographical memories. Much less is known about how blind children's autobiographical memory develops in the absence of visual information. Using cue‐word methodology, 36 sighted and 33 blind early teenagers were asked to recall memories and subsequently rated phenomenological qualities of their memories. Retrieval latency, the number of prompts provided, episodic and non‐episodic details reported for each memory were coded. In terms of memory accessibility, the blind group recalled comparable number of memories with comparable latency to retrieve memories, but they needed more prompting. Blind participants recalled similar number of episodic details; however, they reported more extraneous details, decreasing specificity. Blind early teenagers reported higher auditory imagery, a propensity to remember events from the first‐person perspective, and a tendency to remember events as coherent stories.

The functional role of visual information and fixation stillness in the quiet eye.

The final fixation to a target in far-aiming tasks, known as the quiet eye, has been consistently identified as an important perceptual-cognitive variable for task execution. Yet, despite a number of proposed mechanisms it remains unclear whether the fixation itself is driving performance effects or is simply an emergent property of underpinning cognitions. Across two pre-registered studies, novice golfers (n = 127) completed a series of golf putts in a virtual reality simulation to examine the function of the quiet eye in the absence of visual information. In experiment 1 participants maintained a quiet eye fixation even when all visual information was occluded. Visual occlusion did significantly disrupt motor skill accuracy, but the effect was relatively small (89cm vs 105cm radial error, std. beta = 0.25). In experiment 2, a 'noisy eye' was induced using covertly moving fixation points, which disrupted skill execution (p = .04, BF = 318.07, std. beta = -0.25) even though visual input was equivalent across conditions. Overall, the results showed that performers persist with a long pre-shot fixation even in the absence of visual information, and that the stillness of this fixation confers a functional benefit that is not merely related to improved information extraction.

Beyond the Eye: Multisensory Contributions to the Sensation of Illusory Self-Motion (Vection)

Abstract Vection is typically defined as the embodied illusion of self-motion in the absence of real physical movement through space. Vection can occur in real-life situations (e.g., ‘train illusion’) and in virtual environments and simulators. The vast majority of vection research focuses on vection caused by visual stimulation. Even though visually induced vection is arguably the most compelling type of vection, the role of nonvisual sensory inputs, such as auditory, biomechanical, tactile, and vestibular cues, have recently gained more attention. Non-visual cues can play an important role in inducing vection in two ways. First, nonvisual cues can affect the occurrence and strength of vection when added to corresponding visual information. Second, nonvisual cues can also elicit vection in the absence of visual information, for instance when observers are blindfolded or tested in darkness. The present paper provides a narrative review of the literature on multimodal contributions to vection. We will discuss both the theoretical and applied relevance of multisensory processing as related to the experience of vection and provide design considerations on how to enhance vection in various contexts.

Testing Senders' Visual Occlusion Model: Do Operators (Drivers) Really Predict During Visual Occlusion?

The present study tests the hypothesis that humans are capable of predicting the state of a system during visual occlusion, an assumption often made in models of sampling behaviour, but seldom tested. In 1967, John Senders introduced the visual occlusion paradigm to evaluate attentional demand of tasks such as automobile driving. Despite multiple studies employing this paradigm, the concept of operators actually being able to resolve uncertainty during occlusion by predicting system output has remained unvalidated. A self-paced visual occlusion monitoring task was contrived, involving a randomly rotating basin with a ball at the bottom. Participants were required to detect critical events (ball falling off the edge) while looking only as often as subjectively deemed necessary. Assuming the need to resolve uncertainty imposed by the random rotations, we examined relations between occlusion durations and system states preceding occlusion, for different glance durations, to infer whether predicting may have taken place. Results suggested that glance requests were consistent with the use of simple first order predictions. This pertained not only for longer (300 and 500ms) glances, but even for 100ms glances whenever critical events were imminent. The presumption that human operators are capable, under certain circumstances, of predicting system state in the absence of visual information appears feasible; however, glance duration plays an important role. By providing support for some of its basic premises, the use of Senders' visual occlusion paradigm as a potential tool for evaluating human monitoring performance has been strengthened.

Soundspace VR: spatial navigation using sound in virtual reality

Prior research reveals that spatial navigation skills rely mostly in visual sensory abilities, but the study of how spatial processing operates in the absence of visual information is still incomplete. Therefore, a spatial navigation task in virtual reality using auditory cues was developed to study navigational strategies in blindfolded sighted individuals. Twenty healthy adult participants were recruited. The task consisted of a VR scene, in which participants were asked to localize a sound source and move to the target without visual information throughout the entire task. Task difficulty was manipulated by route length and complexity in three different difficulty levels repeated in two different trials. The first trial (learning) consisted of moving to the sound source and then returning to the starting point. The second trial (retrieval) consisted of the same task without the sound source but with auditory cues from obstacles to test spatial learning. Performance was assessed from behavioral measures of execution time, obstacle collisions, and prompts during the task execution. These variables were compared to established neuropsychological instruments for global cognition (Montreal Cognitive Assessment) and memory abilities (Wechsler Memory Scale-R). The results suggested that difficulty level affected navigation performance in both trials. Navigation performance was better in the retrieval trial, but both learning and retrieval trials were explained by global cognitive functioning. These data suggested the Soundspace VR as being effective to study spatial navigation in the absence of visual information and highlight the importance of auditory information from spatial sound cues for spatial navigation and spatial learning.

The Influence of Voice on Pedagogical Agent’s Persona and Recall Performance

Despite the prevalence of computer-generated speech, few studies have investigated the direct relationship between an agent’s voice and students’ perception or recall performance. This study investigated the effects of voice (without visual information) on students’ perception ratings and recall performance. Our results indicated that in the absence of visual information, students greatly preferred the human voice. The recall performance, however, indicated that the synthesized voices led to better recall performance. Implications for pedagogical practices are described in the discussion section.

An effect of eye position in cocktail party listening

Previous studies have noted an interaction between eye position and auditory spatial attention, including a tendency to look towards the location of an attended sound (even in the absence of useful visual information). There can also be objective improvements in the detection and discrimination of sounds when the eyes are directed to their location. In the current study, we were interested in whether there is a measurable effect of eye position in “cocktail party” listening situations. We presented five sequences of digits from five loudspeakers positioned at 0°, ±15° and ±30° azimuth, and asked participants to repeat back the digits presented from one target loudspeaker. In different blocks of trials, the participant was instructed to visually fixate on the target loudspeaker or on a non-target loudspeaker. Head position was stabilized with a neck-rest, and eye position was tracked continuously to monitor compliance. Performance was best when eye fixation was on-target, and suffered when eye fixation was off-target, particularly for targets located in the center. This result demonstrates an influence of eye position in multitalker mixtures, even in the absence of visual information (lip-reading, etc), and suggests that optimal performance depends on the spatial alignment of auditory and visual attention.

Gaze direction influences grasping actions towards unseen, haptically explored, objects

Haptic exploration produces mental object representations that can be memorized for subsequent object-directed behaviour. Storage of haptically-acquired object images (HOIs), engages, besides canonical somatosensory areas, the early visual cortex (EVC). Clear evidence for a causal contribution of EVC to HOI representation is still lacking. The use of visual information by the grasping system undergoes necessarily a frame of reference shift by integrating eye-position. We hypothesize that if the motor system uses HOIs stored in a retinotopic coding in the visual cortex, then its use is likely to depend at least in part on eye position. We measured the kinematics of 4 fingers in the right hand of 15 healthy participants during the task of grasping different unseen objects behind an opaque panel, that had been previously explored haptically. The participants never saw the object and operated exclusively based on haptic information. The position of the object was fixed, in front of the participant, but the subject’s gaze varied from trial to trial between 3 possible positions, towards the unseen object or away from it, on either side. Results showed that the middle and little fingers’ kinematics during reaching for the unseen object changed significantly according to gaze position. In a control experiment we showed that intransitive hand movements were not modulated by gaze direction. Manipulating eye-position produces small but significant configuration errors, (behavioural errors due to shifts in frame of reference) possibly related to an eye-centered frame of reference, despite the absence of visual information, indicating sharing of resources between the haptic and the visual/oculomotor system to delayed haptic grasping.

Reflections on working with adolescents during the Covid-19 pandemic

ABSTRACT The paper offers a personal reflection on working for a charity offering psychotherapeutic help to adolescents in an inner London borough during the Covid-19 pandemic. The paper highlights the importance of considering the adolescent’s material circumstances together with their developmental needs when setting up remote work. It explores the unconscious meaning of remote contact and of the adolescent’s choice of a teletherapy modality, as well as the role of fantasy and the body in the absence of visual information. The paper also considers the impact remote working has had on the boundaries and dynamics of psychotherapy.

Children five-to-nine years old can use path integration to build a cognitive map without vision

Although spatial navigation competence improves greatly from birth to adulthood, different spatial memory capacities emerge at different ages. Here, we characterized the capacity of 5–9-year-old children to use path integration to build egocentric and allocentric spatial representations to navigate in their environment, and compared their performance with that of young adults. First, blindfolded participants were tested on their ability to return to a starting point after being led on straight and two-legged paths. This egocentric homing task comprising angular and linear displacements allowed us to evaluate path integration capacities in absence of external landmarks. Second, we evaluated whether participants could use path integration, in absence of visual information, to create an allocentric spatial representation to navigate along novel paths between objects, and thus demonstrate the ability to build a cognitive map of their environment. Ninety percent of the 5–9-year-old children could use path integration to create an egocentric representation of their journey to return to a starting point, but they were overall less precise than adults. Sixty-four percent of 5–9-year-old children were capable of using path integration to build a cognitive map enabling them to take shortcuts, and task performance was not dependent on age. Imprecisions in novel paths made by the children who built a cognitive map could be explained by poorer integration of the experienced turns during the learning phase, as well as greater individual variability. In sum, these findings demonstrate that 5–9-year-old children can use path integration to build a cognitive map in absence of visual information.

The quality of visual information about the lower extremities influences visuomotor coordination during virtual obstacle negotiation.

Successful negotiation of obstacles during walking relies on the integration of visual information about the environment with ongoing locomotor commands. When information about the body and the environment is removed through occlusion of the lower visual field, individuals increase downward head pitch angle, reduce foot placement precision, and increase safety margins during crossing. However, whether these effects are mediated by loss of visual information about the lower extremities, the obstacle, or both remains to be seen. Here we used a fully immersive, virtual obstacle negotiation task to investigate how visual information about the lower extremities is integrated with information about the environment to facilitate skillful obstacle negotiation. Participants stepped over virtual obstacles while walking on a treadmill with one of three types of visual feedback about the lower extremities: no feedback, end-point feedback, and a link-segment model. We found that absence of visual information about the lower extremities led to an increase in the variability of leading foot placement after crossing. The presence of a visual representation of the lower extremities promoted greater downward head pitch angle during the approach to and subsequent crossing of an obstacle. In addition, having greater downward head pitch was associated with closer placement of the trailing foot to the obstacle, further placement of the leading foot after the obstacle, and higher trailing foot clearance. These results demonstrate that the fidelity of visual information about the lower extremities influences both feedforward and feedback aspects of visuomotor coordination during obstacle negotiation. NEW & NOTEWORTHY Here we demonstrate that visual information about the lower extremities is utilized for precise foot placement and control of safety margins during obstacle negotiation. We also found that when a visual representation of the lower extremities is present, this information is used in the online control of foot trajectory. Together, our results highlight how visual information about the body and the environment is integrated with motor commands for planning and online control of obstacle negotiation.

Rapid recalibration of speech perception after experiencing the McGurk illusion.

The human brain can quickly adapt to changes in the environment. One example is phonetic recalibration: a speech sound is interpreted differently depending on the visual speech and this interpretation persists in the absence of visual information. Here, we examined the mechanisms of phonetic recalibration. Participants categorized the auditory syllables /aba/ and /ada/, which were sometimes preceded by the so-called McGurk stimuli (in which an /aba/ sound, due to visual /aga/ input, is often perceived as ‘ada’). We found that only one trial of exposure to the McGurk illusion was sufficient to induce a recalibration effect, i.e. an auditory /aba/ stimulus was subsequently more often perceived as ‘ada’. Furthermore, phonetic recalibration took place only when auditory and visual inputs were integrated to ‘ada’ (McGurk illusion). Moreover, this recalibration depended on the sensory similarity between the preceding and current auditory stimulus. Finally, signal detection theoretical analysis showed that McGurk-induced phonetic recalibration resulted in both a criterion shift towards /ada/ and a reduced sensitivity to distinguish between /aba/ and /ada/ sounds. The current study shows that phonetic recalibration is dependent on the perceptual integration of audiovisual information and leads to a perceptual shift in phoneme categorization.

A Matter of (Inner) Balance: The Association Between Facets of Mindfulness, Attention Deficit, and Postural Stability

Mindfulness and motor performance are theoretically related through attention and awareness, yet little research has been conducted to date. The present study was aimed at exploring the role of facets of mindfulness in static and dynamic balance tasks. Specifically, 103 college students and staff completed the five facets of mindfulness questionnaire (which assesses awareness, non-reacting, non-judging, observing, and describe) and participated in eight motor tasks (e.g. standing on 1 ft, tandem walk, etc.). Motor performance was assessed by measuring participants’ mediolateral trunk sway. Hierarchical regression analyses revealed that the facet of observing was associated with more stable performance in the absence of visual information. Furthermore, predisposed awareness was associated with less stable performance when attention was divided and in the absence of visual information. Moreover, awareness interacted with attention deficit disorder, such that as compared to non-ADD/ADHDs, participants diagnosed with ADD/ADHD performed worse in static balance tasks if their awareness was low but performed better if their awareness was high. However, an opposite pattern was found for dual-task gait performance, thus indicating on stereotype threat effect. These findings are discussed from the perspectives of recent mindful movement and the fringe consciousness frameworks.

Sensorimotor Skills Impact on Temporal Expectation: Evidence from Swimmers.

Aim of this study was to assess whether the ability to predict the temporal outcome of a sport action was influenced by the sensorimotor skills previously acquired during a specific sport training. Four groups, each of 30 subjects, were enrolled in this study; subjects of three groups practiced different sports disciplines (i.e., swimming, rhythmic gymnastics, and water polo) at competitive level whilst the fourth group consisted of control subjects. Subjects were asked to observe a video showing a swimmer doing two laps in crawl style. This video was shown 36 times, and was occluded after variable intervals, randomized across trials, by a dark window that started 3, 6, and 12 s before the swimmer touched the poolside. During the occluded interval, subjects were asked to indicate when the swimmer touched the edge of the pool by clicking on any button of the laptop keyboard. We found that swimmers were more accurate than subjects performing other sports in temporally predicting the final outcome of the swimming task. Particularly, we observed a significant difference in absolute timing error that was lower in swimmers compared to other groups when they were asked to make a temporal prediction with the occluded interval of short duration (i.e., 3 s). Our findings demonstrate that the ability to extract temporal patterns of a motor action depends largely on the subjective expertise, suggesting that sport-acquired sensorimotor skills impact on the temporal representation of the previously observed action, allowing subjects to predict the time course of the action in absence of visual information.

Emotional Mimicry Beyond the Face?

Emotional mimicry—quick and spontaneous matching of another’s expressions—is a well-documented phenomenon that is associated with numerous social outcomes. Although the mechanisms underlying mimicry are not fully understood, there is growing awareness that it is more than a one-to-one motor matching of others’ expressions and may be the result of neural simulation. If true, it is possible that mimicry could extend to other parts of the body, even in the absence of visual information from that body part. Indeed, we found that passively viewing anger and fear expressions, without accompanying information from the body, voice or other channels, produced both facial mimicry and corresponding responses in arm muscles that make a fist or a defensive posture. This suggests that observers simulated observed expressions and that activity may have spilled over to other areas to create a body response.

A novel mechanism for mechanosensory-based rheotaxis in larval zebrafish.

When flying or swimming, animals must adjust their own movement to compensate for displacements induced by the flow of the surrounding air or water1. These flow-induced displacements can most easily be detected as visual whole-field motion with respect to the animal’s frame of reference2. In spite of this, many aquatic animals consistently orient and swim against oncoming flows (a behavior known as rheotaxis) even in the absence of visual cues3,4. How animals achieve this task, and its underlying sensory basis, is still unknown. Here we show that in the absence of visual information, larval zebrafish (Danio rerio) perform rheotaxis by using flow velocity gradients as navigational cues. We present behavioral data that support a novel algorithm based on such local velocity gradients that fish use to efficiently avoid getting dragged by flowing water. Specifically, we show that fish use their mechanosensory lateral line to first sense the curl (or vorticity) of the local velocity vector field to detect the presence of flow and, second, measure its temporal change following swim bouts to deduce flow direction. These results reveal an elegant navigational strategy based on the sensing of flow velocity gradients and provide a comprehensive behavioral algorithm, also applicable for robotic design, that generalizes to a wide range of animal behaviors in moving fluids.

Eye Tracking of Occluded Self-Moved Targets: Role of Haptic Feedback and Hand-Target Dynamics.

Previous studies on smooth pursuit eye movements have shown that humans can continue to track the position of their hand, or a target controlled by the hand, after it is occluded, thereby demonstrating that arm motor commands contribute to the prediction of target motion driving pursuit eye movements. Here, we investigated this predictive mechanism by manipulating both the complexity of the hand-target mapping and the provision of haptic feedback. Two hand-target mappings were used, either a rigid (simple) one in which hand and target motion matched perfectly or a nonrigid (complex) one in which the target behaved as a mass attached to the hand by means of a spring. Target animation was obtained by asking participants to oscillate a lightweight robotic device that provided (or not) haptic feedback consistent with the target dynamics. Results showed that as long as 7 s after target occlusion, smooth pursuit continued to be the main contributor to total eye displacement (∼60%). However, the accuracy of eye-tracking varied substantially across experimental conditions. In general, eye-tracking was less accurate under the nonrigid mapping, as reflected by higher positional and velocity errors. Interestingly, haptic feedback helped to reduce the detrimental effects of target occlusion when participants used the nonrigid mapping, but not when they used the rigid one. Overall, we conclude that the ability to maintain smooth pursuit in the absence of visual information can extend to complex hand-target mappings, but the provision of haptic feedback is critical for the maintenance of accurate eye-tracking performance.

The maintenance and updating of representations of no longer visible objects and their parts.

When an object partially or completely disappears behind an occluding surface, a representation of that object persists. For example, fragments of no longer visible objects can serve as an input into mid-level constructive visual processes, interacting and integrating with currently visible portions to form perceptual units and global motion signals. Remarkably, these persistent representations need not be static and can have their positions and orientations updated postdictively as new information becomes visible. In this chapter, we highlight historical considerations, behavioral evidence, and neural correlates of this type of representational updating of no longer visible information at three distinct levels of visual processing. At the lowest level, we discuss spatiotemporal boundary formation in which visual transients can be integrated over space and time to construct local illusory edges, global form, and global motion percepts. At an intermediate level, we review how the visual system updates form information seen at one moment in time and integrates it with subsequently available information to generate global shape and motion representations (e.g., spatiotemporal form integration and anorthoscopic perception). At a higher level, when an entire object completely disappears behind an occluder, the object's identity and predicted position can be maintained in the absence of visual information.

Auditory spatial representations of the world are compressed in blind humans

Compared to sighted listeners, blind listeners often display enhanced auditory spatial abilities such as localization in azimuth. However, less is known about whether blind humans can accurately judge distance in extrapersonal space using auditory cues alone. Using virtualization techniques, we show that auditory spatial representations of the world beyond the peripersonal space of blind listeners are compressed compared to those for normally sighted controls. Blind participants overestimated the distance to nearby sources and underestimated the distance to remote sound sources, in both reverberant and anechoic environments, and for speech, music, and noise signals. Functions relating judged and actual virtual distance were well fitted by compressive power functions, indicating that the absence of visual information regarding the distance of sound sources may prevent accurate calibration of the distance information provided by auditory signals.