Developing a Wearable Tactile Prototype to Support Situational Awareness
Flynn Wolf · 2016 · Proceedings of the 13th International Web for All Conference (W4A) · doi:10.1145/2899475.2899505
Summary
This doctoral consortium paper from UMBC describes dissertation research into head-mounted tactile displays for spatial and situational awareness, with applications for people who are blind and those experiencing situational impairments. The research program is grounded in Wickens' Multiple Resource Theory — the idea that sensory channels have parallel attentional resources, meaning visually overloaded users could benefit from well-designed tactile cues delivered through an underutilized sensory channel. Wolf began with participatory design research (surveys and focus groups) to understand realistic conditions for mobile multitasking and tactile interaction, which produced a common descriptive vocabulary for tactile effects and use case scenarios. This informed the design of multi-parameter tactile signals (varying amplitude, waveform, rhythmic pattern, and display location on the head) delivered through a head-mounted device. The research applies Endsley's three-level model of situational awareness — perception, comprehension, and prediction — using the SAGAT (Situation Awareness Global Assessment Technique) freeze-probe method to assess how tactile signals interact with users' ongoing cognitive processing of their surroundings.
Key findings
Two perceptual experiments yielded actionable design conclusions for head-mounted tactile interfaces. The first experiment found that participants had higher error rates and cognitive workload with sine wave signals and signals where rhythmic intervals changed, identifying signal parameters that should be avoided or carefully managed in tactile coding schemes. The second experiment tested a revised three-parameter tactile coding scheme as a spatial awareness prototype, with participants sitting and walking on a treadmill at varying speeds to assess the interaction between physical exertion and tactile perception. Significant interaction was found between exertion condition and subjective cognitive workload. SAGAT probe accuracy varied with exertion level but was broadly consistent with related studies. The relationship between the three situational awareness phases was also consistent with theory: perception and prediction scores outpaced comprehension, suggesting that users could detect and anticipate tactile-conveyed spatial information more easily than they could integrate it into a full understanding of the situation. The author emphasizes that the design conclusions are not a parameter cookbook but rather guidance on how tactile design factors interact to produce effective alerting.
Relevance
This research explores an important frontier in assistive technology: using the tactile sense — specifically through head-worn devices — to convey spatial and contextual information that is normally visual. For people who are blind, head-mounted tactile displays could provide discreet, hands-free alerts about approaching hazards or spatial events without competing with auditory information from the environment or screen readers. The concept of "situational impairment" broadens the applicability beyond permanent disabilities to include anyone whose visual or auditory attention is occupied, such as pedestrians using smartphones. For accessibility practitioners and wearable developers, the key takeaway is that tactile signal design requires careful attention to parameters like waveform and rhythm — poorly chosen signals increase cognitive load rather than reducing it. The participatory design foundation ensures the research addresses real user concerns rather than purely technical possibilities, and the application of formal situational awareness assessment methods brings rigor to an area often evaluated only through simple task completion metrics.
Tags: haptic technology · wearable technology · tactile accessibility · blindness · situational impairment · navigation · participatory design · spatial awareness