Factors Affecting Line Tracing in Tactile Graphs

Twenty-four braille readers in grades 4 to 12 performed a line-tracking task on tactile line graphs which differed in the type of raised line used to represent the data curve (continuous-interrupted, narrow-wide) and the nature of the display background (grid, no grid). A grid was found to impair the trackability of every line tested, despite high levels of discriminability between the test lines and the grid line. Line type and grade level had only marginal effects on tracking proficiency. Implications for the design of tactile line graphs for the blind are discussed.