TextSL: A Command-Based Virtual World Interface for the Visually Impaired
Eelke Folmer, Bei Yuan, Dave Carr, Manjari Sapre · 2009 · Proceedings of the 11th International ACM SIGACCESS Conference on Computers and Accessibility (Assets '09) · doi:10.1145/1639642.1639654
Summary
This paper presents TextSL, a text-based client for the virtual world Second Life that enables access via screen readers. Second Life is a non-game virtual world where users control avatars to explore 3D environments, socialise with others, and interact with user-created objects — activities that are entirely inaccessible through the standard graphical viewer to people who are visually impaired. TextSL replaces the visual interface with a command-based system where users type commands such as "move north 20", "describe objects", "say Hello", or "where is the chair?" to perform all the actions available in the standard viewer. The system connects to Second Life through the libsecondlife library and presents the virtual world as text descriptions. Key features include a summariser that retrieves and prioritises all objects and avatars within a 20-metre radius (ranked by distance, with longer names assumed to be more descriptive), collision-free navigation using A* pathfinding that automatically teleports users past obstacles, partial name matching to avoid exact typing requirements, and a "help" command system for learning available actions. TextSL was released as open source under the GNU Public License and downloaded over 420 times from textsl.org. The paper also includes an analysis of object naming practices in Second Life, sampling 433 regions to assess accessibility barriers.
Key findings
A user study compared 4 screen reader users with 4 sighted users performing exploration, communication, navigation, and object interaction tasks. Screen reader users using TextSL were able to perform exploration, communication, and interaction with the same success rate as sighted users using the standard Second Life viewer (Fisher's exact probability p>0.05 for all). Communication task performance showed no significant difference between interfaces. However, command-based exploration and object interaction were significantly slower — the tutorial took screen reader users an average of 1137 seconds versus 528 for sighted users, and the main task took similar proportionally longer times. The object naming analysis revealed that 31.3% (SD=21.4%) of objects in Second Life are named "object" (the default), with this figure varying significantly by region (up to 85% in some areas). Further analysis showed about 40% of objects lack descriptive names, creating a major accessibility barrier. Screen reader users issued an average of 0.75 unrecognised commands (SD=0.17), and sighted users averaged 0.38 mistakes (SD=0.17), suggesting the command interface is reasonably learnable. Sighted users were slightly more satisfied with usability but the difference was not statistically significant (t=1.48, p>0.1).
Relevance
This work addresses the accessibility of virtual worlds — an area that has grown increasingly important as 3D social environments, metaverse platforms, and online gaming become mainstream channels for social interaction, education, commerce, and employment. The finding that 31-40% of objects in Second Life lack descriptive names directly parallels the web accessibility problem of missing alternative text for images, suggesting that user-generated 3D content faces the same metadata gap as user-generated web content. TextSL demonstrates that a command-based interface is a viable accessibility approach for 3D environments, achieving equivalent task completion rates for communication and interaction despite being slower for exploration. The architectural approach — creating an alternative client that translates visual spatial information into structured text — provides a model applicable to modern virtual reality and metaverse platforms. The research highlights that social interaction, the most valued aspect of virtual worlds, can be made accessible with comparable efficiency, while spatial navigation remains the hardest challenge to address non-visually.
Tags: virtual worlds · visual impairment · screen readers · game accessibility · social interaction · command-line interface · Second Life · alternative interface