The Detection of Length and Orientation Changes in Dynamic Vibrotactile Patterns

Vibrotactile thresholds for the detection of length and orientation changes were determined for dynamic line patterns presented on the Optacon in a forced-choice procedure. Even the smallest changes in both length (1.2 mm) and orientation (7°) could be detected in the absence of any other changes in the vibrotactile pattern. The introduction of translations increased the length-change threshold to approximately 4.0 mm, and the introduction of length changes increased the orientation-change threshold to approximately 25°. The effects of several additional variables were assessed; these included the use of filled and unfilled lines, the timing of presentation, and the position of stimuli on the array. The implications for the perception of depth in dynamic vibrotactile patterns are discussed