Nonvisual Support for Understanding and Reasoning about Data Structures

TL;DR

This work addresses the accessibility gap for blind and visually impaired students learning data structures by preserving the computational structure of diagrams across nonvisual modalities. It introduces Arboretum, a structure first system that automatically generates synchronized tabular, navigable, and tactile representations from diagram specifications expressed in languages like Mermaid and Graphviz DOT. Derived from a Wizard of Oz study, five design requirements guide the system, and an evaluation with eight BVI learners demonstrates that tactile graphics yield strong comprehension and efficient navigation while multimodal integration supports verification and mental model development. The findings support scalable accessible CS education by enabling educators to author and maintain diagram content that preserves structural meaning across modalities, with implications for extending to broader diagram types and domains.

Abstract

Blind and visually impaired (BVI) computer science students face systematic barriers when learning data structures: current accessibility approaches typically translate diagrams into alternative text, focusing on visual appearance rather than preserving the underlying structure essential for conceptual understanding. More accessible alternatives often do not scale in complexity, cost to produce, or both. Motivated by a recent shift to tools for creating visual diagrams from code, we propose a solution that automatically creates accessible representations from structural information about diagrams. Based on a Wizard-of-Oz study, we derive design requirements for an automated system, Arboretum, that compiles text-based diagram specifications into three synchronized nonvisual formats$\unicode{x2013}$tabular, navigable, and tactile. Our evaluation with BVI users highlights the strength of tactile graphics for complex tasks such as binary search; the benefits of offering multiple, complementary nonvisual representations; and limitations of existing digital navigation patterns for structural reasoning. This work reframes access to data structures by preserving their structural properties. The solution is a practical system to advance accessible CS education.

Figures (7)

• Figure 1: Representations of standard array and binary tree diagrams as seen in a slide deck.
• Figure 2: A system overview of Arboretum: an (a) input stage with a selected data structure and a provided Mermaid diagram specification, a (b) translation stage compiles the input into the IR, extracting and deriving additional properties, and an (c) output stage that generates accessible output representations.
• Figure 3: Examples of Mermaid (a) and Graphviz DOT (b) input syntax for the same binary tree compiled into Arboretum's shared IR (c), which unifies distinct diagram formats into a shared, semantically consistent model.
• Figure 4: IRs generated by Arboretum for arrays (a) with examples of generalization to linked lists (b) and two-dimensional arrays (c).
• Figure 5: Arboretum's Editor mode, which allows educators to write diagram specifications and preview synchronized accessible outputs.