Importance of force feedback for following uneven virtual paths with a stylus

It is commonly known that a physical textured path can be followed by indirect touch through a probe also in absence of vision if sufficiently informative cues are delivered by the other sensory channels, but prior research indicates that the level of performance while following a virtual path on a touchscreen depends on the type and channel such cues belong to. The re-enactment of oriented forces, as they are induced by localized obstacles in probe-based exploration, may be important to equalize the performance between physical and virtual path following. Using a stylus attached to a force-feedback arm, an uneven path marked by virtual bars was traversed while time and positions were measured under normal sensory conditions, as well as in absence of vision or hearing. Alternatively, participants followed the same path on a wooden tablet provided with physical bars in relief (i.e., without receiving synthetic force) under the same conditions. The visual conditions were found to be significantly faster than the non-visual conditions. However, there was no significant advantage of traversing either path. In contrast to previous experiments in which the virtual bars were rendered using vibrotactile and/or auditory cues, comparable times to traverse the physical and virtual path were found also when vision was disabled. Our results hence suggest that users who are deprived of vision follow textured virtual paths as efficiently as physical paths, if unevenness is rendered using restorative force cues through a stylus.