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.
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