AngleSizer: Enhancing Spatial Scale Perception for the Visually Impaired with an Interactive Smartphone Assistant

TL;DR

AngleSizer addresses the challenge of teaching small- and medium-scale spatial concepts to BVI users by introducing a smartphone-based, gesture-driven teaching assistant that combines dual-channel feedback with three learning modules. Through a formative study and a 10-day user study with 11 participants, the system demonstrates significant improvements in spatial-perception accuracy (mean relative error reduced from $0.234$ to $0.097$, ~58.5% improvement) and positive subjective outcomes, while maintaining practical accuracy via inherent and operational error analyses. The work highlights an approach that leverages natural hand/body gestures, IMU/camera data, and tactile-audio feedback to enable independent, cost-effective learning and real-world application, with implications for education and assistive technology. Overall, AngleSizer contributes to the HCI literature on accessible, real-world training tools that empower BVI individuals to develop proprioceptive spatial skills and confidence in daily activities.

Abstract

Spatial perception, particularly at small and medium scales, is an essential human sense but poses a significant challenge for the blind and visually impaired (BVI). Traditional learning methods for BVI individuals are often constrained by the limited availability of suitable learning environments and high associated costs. To tackle these barriers, we conducted comprehensive studies to delve into the real-world challenges faced by the BVI community. We have identified several key factors hindering their spatial perception, including the high social cost of seeking assistance, inefficient methods of information intake, cognitive and behavioral disconnects, and a lack of opportunities for hands-on exploration. As a result, we developed AngleSizer, an innovative teaching assistant that leverages smartphone technology. AngleSizer is designed to enable BVI individuals to use natural interaction gestures to try, feel, understand, and learn about sizes and angles effectively. This tool incorporates dual vibration-audio feedback, carefully crafted teaching processes, and specialized learning modules to enhance the learning experience. Extensive user experiments validated its efficacy and applicability with diverse abilities and visual conditions. Ultimately, our research not only expands the understanding of BVI behavioral patterns but also greatly improves their spatial perception capabilities, in a way that is both cost-effective and allows for independent learning.

Figures (16)

• Figure 1: Drawing on insights into real-world challenges faced by the BVI, we proposed AngleSizer. This smartphone assistant supports various interaction gestures, helping BVI users learn about spatial scales through setting study goals, independent exploration, and feedback for corrections. Repeated practice with AngleSizer aids in the BVI developing muscle memory, thereby enhancing spatial perception.
• Figure 2: Visual condition and educational background of the questionnaire recipients.
• Figure 3: We are doing the door-to-door research. Those with black rectangles covering their faces are the blind or low-vision. (a) Talking about his own situation. (b) Describing the sizes of objects around her. (c) Trying to illustrate a size on a mat with scales.
• Figure 4: The BVI face many realistic problems related to scales in their daily life and try to solve them although it is time-consuming and laborious. (a1)and (a2) show that a blind couple uses their hands to feel the size of the cake. (b1) and (b2) show that a blind person uses a braille ruler to measure the laptop by touching and counting holes.
• Figure 5: The system design of AngleSizer inspired by preliminary research, including the interaction gestures, feedback mechanisms, teaching processes, and learning modules.