Factors Affecting Traceability of Lines for Tactile Graphics

To facilitate appropriate line choice for tactile graphic displays, 42 visually impaired subjects traced four types of tactile lines in a simple display (without intersections), and in a complex display (having intersections). The lines were single smooth, double smooth (1/4 in. [. 635 cm ] spacing), single rough, and double rough. Measures were taken of time to complete the task, “behaviors” other than the continuous tracing of a line, and “restarts,” in which subjects required assistance to complete the task. The results indicate which line types may be more readily traced in displays with and without intersections .