IntroductionAs we walk we perceive our motion by external channels such as vision, and by internal ones such as the vestibular and proprioceptive senses. But what happens when these channels offer contradicting information? Previous work has shown that by manipulating visual gain during movement the user’s path can be redirected, a procedure known as redirected walking. While the behavioral dominance of visual cues on the immediate path has been well demonstrated, potential residual effects of the internal senses on path integration have not been well quantified - will it disrupt participant’s answer in the visual reference frame or even bias it towards the correct answer by the internal cues reference frame as part of a weighted integration process? Or will vision dominate to the point where it suppresses the other clashing inputs? Furthermore, it is unclear to what extent such effects might be consistent within and across individuals.MethodsHere, we use the classic triangle completion task combined with redirected walking to quantify this balance and test for accuracy in the visual reference frame vs. the idiothetic reference frame.ResultsWe find that as expected vision dominates participants' conscious perception, that accuracy within the idiothetic reference frame is low on average compared to the control of performing the tasks without redirection, and that it is modulated by the level of redirected gain in a way which is generally stable within individuals. However, we also find significant individual differences across participants with some even having an opposite strong and stable bias towards the idiothetic reference frame.DiscussionThese findings offer insight into the basic science of human navigation and multisensory integration, and hold implications for practical applications in virtual environment design and locomotion with redirected walking. Specifically, VR developers and researchers should keep in mind that just because a user’s path is being properly redirected, it does not mean that their real-world physical path does not leave traces in their internal representations of space and may potentially have residual effects on their spatial memory in the individual participant level.

The October 7 attacks caused significant psychological trauma among Israeli soldiers and civilians. Virtual reality (VR) has shown promise in PTSD treatment, particularly through BraveMind, a validated Prolonged Exposure (PE) VR system developed for U.S. veterans. This formative study examined how existing VR tools can be adapted to the Israeli context and extended beyond exposure to include place-attachment-based therapy for displaced civilians. Seven experienced clinicians participated in a focus-group evaluation of two systems: the original U.S.-based BraveMind and a newly developed place-attachment VR prototype (Re-PAVeR). Participants individually experienced brief VR exposures and completed questionnaires assessing presence, user experience, and perceived clinical utility, followed by a structured group discussion. Clinicians reported a strong sense of presence and positive attitudes toward VR-based interventions. They emphasized the importance of cultural, geographical, and operational adaptations to reflect Israeli combat and civilian trauma and highlighted the potential of attachment-based VR environments for addressing grief and loss among evacuees. Based on extensive prior validation of BraveMind and the present expert feedback, the findings support further development and contextual adaptation of VR-based interventions for PTSD treatment in Israel.

Virtual reality (VR) is a powerful tool for researching human spatial memory, but potential differences between user behavior in virtual versus real environments are often confounded by multiple entangled factors such as locomotion type (e.g. physical vs. virtual), interface (e.g. keyboard vs. motion), and the user’s surrounding physical environment. A less explored factor is Reality Modality—effects that arise from knowing an environment is virtual rather than real. While reality modality is widely assumed to matter, its effects have rarely been tested independently due to challenges with isolating it. Here, we tested participants on the same spatial memory task in three matched conditions designed to isolate its effects—(1) Real-world passthrough Augmented Reality (AR) (2) immersive VR reconstructed by scanning the same real environment and using the same headset and interface in the same physical room, and (3) a traditional desktop setup. We found no significant differences between AR and VR in subjective measures such as immersion, enjoyment, difficulty, cybersickness, or in the objective measure of spatial memory accuracy. In contrast, both outperformed the desktop condition across all measures. These results suggest that if VR environments are naturalistic enough in design, interface and movement affordances, reality modality itself has limited influence on spatial memory and therefore spatial memory performance in them will match real world performance despite taking place in VR. Our findings increase our basic science understanding of the parameter of Reality Modality and the disentangled contribution of different parameters to spatial memory accuracy, with implications for the design of extended reality applications and for generalizing results along the virtuality-reality continuum.

Epidural analgesia is challenging, especially for novice anesthesiologists. Traditional approaches, relying on the ‘see one, do one, teach one’ paradigm, limit opportunities for extensive practice without patient risk. To address this challenge, a haptic-only simulator was previously developed and evaluated. In this study, we added immersive visualizations using Unity and Chai-3D platforms, creating two visuo-haptic simulators. We tested to see how these visual components would affect the simulator’s face validity (realism) and content validity (perception of training effectiveness), and whether they would compromise performance. Twenty anesthesiologists of varying experience levels performed simulated epidural needle insertions using each simulator. We evaluated face and content validity through visual analog scale (VAS) questionnaires, and assessed user performance based on success rates and error measures. No statistically significant differences were found between the three simulators in user preference or performance metrics. The Unity-based simulator received slightly higher scores for visual realism, while the ‘Chai-3D’ simulator showed marginally better performance. Considering expert feedback and practical considerations such as ease of setup and seamless integration between the haptic and visual components, the ‘Chai-3D’ simulator emerged as the most suitable option for future use.

New technologies unlock new possibilities for academic teaching. Virtual Reality (VR) makes teaching experiential, shifting from listening to firsthand experiencing. Large Language Models (LLMs) make teaching interactive, enabling dynamic scenarios. Here we focus on their combination - immersive VR scenarios with LLM agents. As a case-study we taught simulation theory - the question of whether we are living in a simulation. We created a VR simulation with an LLM agent and challenged students to convince it that it was living in a virtual world. We also had students watch volunteers perform this task, and challenged them to convince us that they were real. The students responded enthusiastically to the experience. It also decreased their belief that they could convince an avatar it was virtual or other humans that they are real. This case-study demonstrates the potential of combining VR and LLM-based avatar for academic teaching and for education in general.

Improving obstacles visibility can improve mobility, a significant challenge for visually challenging scenarios or with visual impairments. As a first step in developing such a system, we examined the experience of walking an obstacle course in typically sighted participants across four conditions passthrough, partial augmentation (physical obstacle outline was augmented), full augmentation (virtual obstacles were fully overlayed on the physical obstacle), and virtual-only objects. Walking time was significantly slower in the partial condition. Interestingly, although the visibility of obstacles differed across augmentations, and affected walking speed, participants did not notice this difference and rated the various augmentations similarly.

Objective. Virtual reality (VR) has become a key tool for researching spatial memory. Virtual environments offer many advantages for research in terms of logistics, neuroimaging compatibility etc. However, it is well established in animal models that the lack of physical movement in VR impairs some neural representations of space, and this is considered likely to be true in humans as well. Furthermore, it is unclear how big the disruptive effect stationary navigation is-how much does physical movement during encoding and recall affect human spatial memory and representations of space? What effect does the fatigue of actually walking during tasks have on participants-will physical movement decrease performance, or increase perception of difficulty?Approach. We utilize Augmented reality (AR) to enable participants to perform a spatial memory task while physically moving in the real world, compared to a matched VR task performed while stationary. Our task was performed by a group of healthy participants, by a group of stationary epilepsy patients, as they represent the population from which invasive human spatial signals are typically collected, and, in a case study, by a mobile epilepsy patient with an investigational chronic neural implant (Medtronic Summit RC + STM) streaming real-time continuous hippocampal local field potential data.Main results. Participants showed good performance in both conditions, but reported that the walking condition was significantly easier, more immersive, and more fun than the stationary condition. Importantly, memory performance was significantly better in walking vs. stationary in all groups, including epilepsy patients. We also found evidence for an increase in the amplitude of the theta oscillations associated with movement during the walking condition.Significance. Our findings highlight the importance of paradigms that include physical movement and suggest that integrating AR with movement in real environments can lead to improved techniques for spatial memory research.

Diagnosing medical conditions is critical for medical personnel. Current training tools include textbooks or descriptive scenarios that lack interactivity and offer limited hands-on experience or expensive scenarios with actors. Interactive virtual simulations hold great promise, but are limited by a lack of tangibleness and realism. We suggest that augmented reality may be a key addition to the training toolbox, specifically augmenting the user’s body, thus providing a tangible platform for interaction. We developed such a self-diagnosis training platform and performed basic usability testing. We found that users could successfully use the platform, with performance correlated with self-reported medical knowledge.

Humans typically utilize vision in a dominant role for navigation. However, what happens when vision becomes actively unreliable? Will it impair user performance, be suppressed, or be used advantageously? While such scenarios are rare in the real world, this question has important implications for multisensory integration in extended reality applications - e.g. virtual walls that a user sees but can walk through. We created virtual mazes which could be solved via audio or visual cues. We then manipulated the reliability of these sensory channels by including invisible walls which are not perceived but still blocked passage, and ghost walls which could be perceived but did not block participants. Participants navigated the exact same layouts under all conditions, and could solve these levels by ignoring the unreliable sensory modality and using only the other. Participants easily completed these mazes using vision-only, and with some difficulty via audition-only. Partially unreliable vision degraded performance, though still above audio-only demonstrating utilization of the unreliable visual cues. Mazes whose entire visual input was false degraded performance to the level of audio only, though participants subjectively reported it as easier then audio-only and did not close their eyes indicating that they still relied on vision. Testing a control in which visual information was both false and constantly moved, preventing its use as landmarks or optic flow, indeed caused participants to close their eyes, disregarding the false vision, but was accompanied by confounding nausea. In parallel, auditory incongruencies were easily suppressed across all unreliable auditory conditions. This demonstrates human attachment to visual information, even when mostly or completely false, and the ability to glean practical advantages from it unless it is completely stripped from usability. More broadly it lays a foundation for testing multisensory integration of sustained false sensory channels, and has implications for mixed reality design.

Virtual and augmented reality hold great potential for understanding spatial cognition. However, it is unclear what effect reality modality has on our perception and interaction with our spatial surroundings. Here, participants performed a spatial memory task using passthrough augmented reality in the real world and in a virtual environment reconstructed by scanning the real environment. We found no significant differences by reality modality for subjective measures such as reported immersion, difficulty, enjoyment and cyber-sickness, nor did we find objective differences in performance. These results suggest limited effects on spatial tasks, and are promising for transfer between virtual and augmented scenarios.

V6 is a retinotopic area located in the dorsal visual stream that integrates eye movements with retinal and visuo-motor signals. Despite the known role of V6 in visual motion, it is unknown whether it is involved in navigation and how sensory experiences shape its functional properties. We explored the involvement of V6 in egocentric navigation in sighted and in congenitally blind (CB) participants navigating via an in-house distance-to-sound sensory substitution device (SSD), the EyeCane. We performed two fMRI experiments on two independent datasets. In the first experiment, CB and sighted participants navigated the same mazes. The sighted performed the mazes via vision, while the CB performed them via audition. The CB performed the mazes before and after a training session, using the EyeCane SSD. In the second experiment, a group of sighted participants performed a motor topography task. Our results show that right V6 (rhV6) is selectively involved in egocentric navigation independently of the sensory modality used. Indeed, after training, rhV6 of CB is selectively recruited for auditory navigation, similarly to rhV6 in the sighted. Moreover, we found activation for body movement in area V6, which can putatively contribute to its involvement in egocentric navigation. Taken together, our findings suggest that area rhV6 is a unique hub that transforms spatially relevant sensory information into an egocentric representation for navigation. While vision is clearly the dominant modality, rhV6 is in fact a supramodal area that can develop its selectivity for navigation in the absence of visual experience.

[This corrects the article DOI: 10.1371/journal.pone.0250281.].

Sensory Substitution Devices (SSDs) convey visual information through audition or touch, targeting blind and visually impaired individuals. One bottleneck towards adopting SSDs in everyday life by blind users, is the constant dependency on sighted instructors throughout the learning process. Here, we present a proof-of-concept for the efficacy of an online self-training program developed for learning the basics of the EyeMusic visual-to-auditory SSD tested on sighted blindfolded participants. Additionally, aiming to identify the best training strategy to be later re-adapted for the blind, we compared multisensory vs. unisensory as well as perceptual vs. descriptive feedback approaches. To these aims, sighted participants performed identical SSD-stimuli identification tests before and after ~75 minutes of self-training on the EyeMusic algorithm. Participants were divided into five groups, differing by the feedback delivered during training: auditory-descriptive, audio-visual textual description, audio-visual perceptual simultaneous and interleaved, and a control group which had no training. At baseline, before any EyeMusic training, participants SSD objects’ identification was significantly above chance, highlighting the algorithm’s intuitiveness. Furthermore, self-training led to a significant improvement in accuracy between pre- and post-training tests in each of the four feedback groups versus control, though no significant difference emerged among those groups. Nonetheless, significant correlations between individual post-training success rates and various learning measures acquired during training, suggest a trend for an advantage of multisensory vs. unisensory feedback strategies, while no trend emerged for perceptual vs. descriptive strategies. The success at baseline strengthens the conclusion that cross-modal correspondences facilitate learning, given SSD algorithms are based on such correspondences. Additionally, and crucially, the results highlight the feasibility of self-training for the first stages of SSD learning, and suggest that for these initial stages, unisensory training, easily implemented also for blind and visually impaired individuals, may suffice. Together, these findings will potentially boost the use of SSDs for rehabilitation.

Modern navigation aids revolutionized human navigation, but are also criticized for potential negative effects on human spatial memory. However, previous tests focused on spatial skills such as environment learning and mental rotations rather then on spatial memory directly. Here, we test directly the effect of a simple navigational aid – an augmented arrow pointing towards the next target – on users’ spatial memory. We find that performance was significantly more efficient with these guiding arrows, but with no significant decrease in spatial memory performance. This suggests negative effects may stem from other features such as attention, and tempers the media’s over-alarmist view.

Spatial memory is a critical function. Without it, we cannot understand our environment, situate ourselves within it, or remember where items are located. Most research on the neural basis of spatial memory is conducted either with invasive brain recordings from animals or with non-invasive imaging in humans. An emerging way to link these areas is by studying rare invasive recordings from the human brain, which can be obtained from epilepsy patients who have electrodes surgically implanted for seizure mapping. In recent years this invasive method has expanded our understanding of how the human brain represents space and has also suggested methods for modulating and potentially rehabilitating memory. However, it is unclear whether these results from epilepsy patients generalize to the non-epileptic population, and from testing in hospital rooms to more immersive and comfortable setups. Here, groups of epilepsy patients (n=69) and healthy participants (n=17) performed the same virtual spatial memory task, enabling us to compare their spatial memory performance. Moreover, we compared spatial memory performance between a standard computer screen versus a head-mounted display. We found that the spatial memory performance of epilepsy patients performing our task in a hospital was similar to that of matched healthy participants performing the task in the lab. Furthermore, actual spatial memory performance was similar on the group level irrespective of the interface used, despite the fact that subjects reported higher immersion with the head mounted display. By showing consistent spatial memory performance with a single paradigm across epilepsy patients and healthy participants, as well as with the use of different display modalities, our results provide a baseline for evaluating findings regarding the neural basis of spatial memory and neuromodulation for rehabilitation. More broadly, these results demonstrate that findings from neurosurgical patients are comparable to the wider population.

Spatial memory is a crucial part of our lives. Spatial memory research and rehabilitation in humans is typically performed either in real environments, which is challenging practically, or in Virtual Reality (VR), which has limited realism. Here we explored the use of Augmented Reality (AR) for studying spatial cognition. AR combines the best features of real and VR paradigms by allowing subjects to learn spatial information in a flexible fashion while walking through a real-world environment. To compare these methods, we had subjects perform the same spatial memory task in VR and AR settings. Although subjects showed good performance in both, subjects reported that the AR task version was significantly easier, more immersive, and more fun than VR. Importantly, memory performance was significantly better in AR compared to VR. Our findings validate that integrating AR can lead to improved techniques for spatial memory research and suggest their potential for rehabilitation. Highlights

Many different visual rehabilitation approaches are being utilized to offer visual information to the blind. User proficiency and functional ability are currently evaluated either via ad-hoc tests or via standardized visual tests which are not sensitive enough in the range of extreme low vision. Unfortunately, this is the functional level that these approaches typically offer. This is especially important as the main criteria by which most users will judge the efficacy of these rehabilitation approaches is by the functional benefits it grants them. Furthermore, currently, there are no accepted benchmarks or clear comparative testing of each rehabilitation approach, leading to the development of many new aids but the practical adoption of few. Combined these indicate a need to add standardized functional tests to this evaluation toolbox. Indeed, several functional tests have recently been suggested but their adoption has been very limited. Here, we review current tests and then conduct a formative study consulting experts in the field to map issues with current standardization attempts. This formative study offered a list of practical design suggestions for functional standardization tests. We then suggest using simple virtual environments as one such family of tests. Virtual scenarios meet many of the experts’ suggestions - they are easy to share, flexible, affordable, safe, identical wherever run, can be run by a single operator and offer control over external parameters enabling a focus on the offered visual information. Finally, we demonstrate this approach via a freely available virtual version of a relatively standard functional test - finding a door - in a 10-minute paradigm which includes 30 trials. We find that congenitally-blind and sighted-blindfolded subjects cannot perform this task without the device, but that they perform it successfully with it, demonstrating the tests’ potential viability.