This work aims to assess the e ect of visual and haptic cues in users with gait impairments; not only in performance, but also in terms of usability, perceived cognitive load, and safety. These haptic cues were delivered via wrist-worn devices, with the goal of supporting these users while out in-the-wild - three types of haptic cues were tested. To further assess the impact of haptic and visual cues outside of a laboratory environment, we used a Virtual Reality Field Study to safely assess the impact of these cues in users' awareness of their surroundings (measured via gaze hits and dwell). Despite conducting a preliminary study with participants not su ering from gait impairments (N=6), our results seem to indicate a positive e ect of the haptic cues in regards to participant cadence, step length, and general awareness of their surroundings when compared to the visual cue. One of the simpler haptic cues was also the preferred stimulus by all participants.
• Applied computing Health informatics; • Human-centered computing Empirical studies in accessibility; Ubiquitous and mobile computing systems and tools.
Copyright © 2020 for this paper by its authors. Use permi ed under Creative Commons License A ribution 4.0 International (CC BY 4.0).
Cross-Reality (XR) Interaction, ACM ISS 2020, November 8 2020, Lisbon, Portugal 1
We agree with Speicher et al.’s expectation that the distinctions
between AR and VR will fade away in time [
Gait disorders, which greatly contribute to a decrease in quality
of life and increased mortality, are common and often devastating
companions of the ageing process [
Our work was primary motivated by Parkinson’s disease, the
second most common neurodegenerative disorder that a ects over
10 million people all over the world [
Cueing consists of sensory spatial and temporal stimulus that
have been shown to minimize the e ect of Parkinson’s disease in
users’ gait [
In this paper we propose to focus particularly on haptic cues.
These types of cues have been demonstrated to be less cognitively
taxing than visual stimuli in navigation tasks, and can be provided
to users in the less distracting and more private form factor of
a wrist-worn device such as a smartwatch or tness tracker;
ultimately leading to a system that is more feasible for continued
use out in-the-wild. Haptic cues have been explored brie y in the
past, demonstrating improvements in users’ posture [
Mostly due to COVID-19 constraints, our preliminary study relies on six patients without any gait impairments. Except for one, these were aged between 18 and 25 years of age (M = 27.0; SD = 11.52); and the majority were students (66.6%). Using a 5-point Likert scale, participants reported being somewhat comfortable with VR technologies (M = 2.00; SD = 1.10). All participants had experience with smartwatches prior to this study. 3.2
This study was performed in a hallway 1m wide and 6.5m long. We relied on VR to simulate a street environment where participant walked in a straight line along a 5m long sidewalk. Several events were included (described as distractors) such as a passing car, a pedestrian that would start walking, and crossing light that would change from red to green (see Figure 1 – left). These events took place after participants walked 1.5, 2.5, and 3.5m, respectively. This was developed using the Unity Game Engine, and deployed on an HCT Vive Pro Eye head-mounted display (combined resolution of 2880×1600 px, 615 PPI, 90Hz, 110° FoV) and eye-tracker (120Hz, 0.5° 1.1° accuracy). Finally, the haptic cues were played on two Huawei Watch 2 and controlled through an Android application where the researcher started and stopped the cues and the VR simulation. The communication between these devices was done via the Open Sound Control (OSC) protocol, and the study complied with the ethics guidelines and COVID-19 regulations in our institution. 3.3
Our study followed a within participants design counterbalanced using a Latin square. It included four cue conditions:
Visual. This followed a classic approach [
cue that uses a simple vibration pattern at speci c intervals [
this cue to explore the idea of playing the haptic pattern above alternatively over two smartwatches, placed on participants’ left and right wrists. This would provide participants with a rhythm with temporal and spatial properties (left and right).
bration patterns were played in sequence on a single smartwatch, attempting to explore the temporal and spatial properties of [1P2W] using a single device. In order to understand the e ects of the cues and distractors on participants’ gait and experience, we measured:
Performance. This included participants’ cadence (steps per min.), step length, and velocity (meters per second). This was calculated by visually counting the number of steps in a trial, and by automatically recording how long it took participants to reach the end of the trial ( ve meters).
Usability. Participants completed the System Usability Scale
(SUS) [
Gaze. In order to assess participants’ awareness of the three distractors included in the scene, we measured the number of gaze hits and dwell time on these across cue conditions. 3.5
The study was conducted in a empty and quiet hallway. Participants were asked to properly disinfect their hands with an 70% alcohol solution, and to clean their face and wrists with disinfecting wipes. This was followed by collecting participants’ demographic information in addiction to to previous experience with VR and smartwatches.
Afterwards, we asked participants to put on both smartwatches, one on each wrist, and to adjust them so they were tight and comfortable. This was followed by the setup and calibration of the VR headset and eye-tracker. The study started by a trial with no stimuli, where baseline measures of participants’ gait parameters were captured (i.e., cadence, step length, and velocity) and feed into the system for personalized stimuli. Participants were asked to walk in a straight line towards the crossing light at the end of the scene (5m), and that the trial would stop when they were close to reaching it. Finally, at the end of each condition participants completed the SUS and took a small break.
At the end of the study participants completed the preference questionnaire. The researcher completed the session by following thoroughly cleaning the headset and watches with disinfecting wipes with at least 70% alcohol. 4
Below we present our preliminary results from six participants. We emphasize that our goal is to improve users’ gait, i.e., have them produce less but longer steps (as opposed to, e.g., the small shu ing steps seen with Parkinsonian gait). Despite not having any gait impairments, our participants’ seem to have been able to improve their cadence and step length in the majority of the haptic conditions (see Figure 2 – left and center), while completing the trial in the approximately same amount of time as with no stimuli (see Figure 2 – right). 4.2
The SUS results for each of the conditions is seen in Table 1. This highlights a preference for the haptic cues relying on a simple vibration pattern played over one or two smartwatches (well above the average SUS score of 68). These results are further corroborated by the preference rankings. All participants’ agreed their favourite cue was the Haptic [1P1W], mostly due to its simple nature requiring very little attention; and all agreed the visual cue to be their least favourite as it required them to continuously look at the oor, often loosing track of their surroundings. 4.3
The gaze results can be seen in Figure 3. These seem to suggest participants were quite aware of their surroundings in both the baseline (no stimuli) and haptic conditions. As expected, the visual condition wielded a potentially lower number of gaze hits and dwell times across distractors – some of these are zero or close to zero, indicating some participants were not aware of some of these distractors at all. While further studies are required, this highlights how impractical and potentially dangerous is this well-studied cue outside of a controlled laboratory environment.
Our immediate future work includes expanding the number of participants in our study, and following-up with participants with some form of gait impairment (particularly participants with Parkinson’s 12 10 ] t un 8 o c [ its 6 H a 4 n e M 2 0 6 ]5 s [ 4 e m i T ll3 e w D 2 n a e 1 M 0 disease) – the ultimate stakeholders of such a system. We will consider running these studies in a wider space, as we suspect our narrow hallway might have a ected participants’ gait at points (for fear of hitting a wall). Ultimately, we aim to develop a smartwatch application for in-the-wild haptic cues that not only aims to normalize users’ gait but is comfortable and safe to use outside of a laboratory. We also suggest a replication of our study via a standard eld study in order to compare ndings. This would enable us to further validate virtual eld studies as a novel research paradigm, particularly in the context of locomotion and mobility tasks. 6
This paper presented a work-in-progress where we explored popular and new stimuli to normalize users’ gait in the context of a VR Field Study. The latter was employed so that we could explore the impact of these cues while walking in a simulated sidewalk; allowing us to start to assess not only the impact of these cues in the overall user experience, but their safety outside of a controlled lab. environment (measured via gaze and awareness of several events). We aim to expand this work via a wearable application that can help address gait disorders in a comfortable, usable, and safe way.