WebAlly: Making Visual Task-based CAPTCHAs Transferable for People with Visual Impairments


Zhuohao Zhang and Zhilin Zhang, University of Illinois at Urbana-Champaign; Haolin Yuan, Johns Hopkins University; Natã M. Barbosa, University of Illinois at Urbana-Champaign; Sauvik Das, Georgia Tech; Yang Wang, University of Illinois at Urbana-Champaign


Task-based visual CAPTCHAs are a significant accessibility hurdle for people with visual impairments (PVIs). What if PVIs could transfer task-based visual CAPTCHAs to a helper to solve? How might PVIs want such a system configured in terms of from whom they would solicit help and how they would compensate this help? To answer these questions, we implemented and evaluated a proof-of-concept assistive transfer system — WebAlly — that makes task-based CAPTCHAs transferable by allowing PVIs to source just-in-time, remote control help from a trusted contact. In an exploratory, role-play study with 10 pairs of participants — a PVI and a friend or a family member — we asked participants to use WebAlly in four different configurations that varied in source of help (friend vs. stranger) and compensation (paid vs. volunteer). We found that PVIs liked having WebAlly as an additional option for solving visual CAPTCHAs, when other options that preserve their independence fail. In addition, many PVIs and their friends felt that using the system would bring their relationship closer. We discuss design implications for transferable CAPTCHAs and assistive transfer systems more broadly, e.g., the importance of complementing rather than replacing PVIs' existing workflows.

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@inproceedings {274441,
author = {Zhuohao Zhang and Zhilin Zhang and Haolin Yuan and Nat{\~a} M. Barbosa and Sauvik Das and Yang Wang},
title = {WebAlly: Making Visual Task-based CAPTCHAs Transferable for People with Visual Impairments},
booktitle = {Seventeenth Symposium on Usable Privacy and Security ({SOUPS} 2021)},
year = {2021},
isbn = {978-1-939133-25-0},
pages = {281--298},
url = {https://www.usenix.org/conference/soups2021/presentation/zhang-zhuohao},
publisher = {{USENIX} Association},
month = aug,
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