Involving multiple fingers in exploring a haptic surface: an evaluation study

In most haptic search tasks, tactile stimuli are usually presented to the fingers to discriminate simulated features and identify patterns. In this paper, we focus on a more complex exploration task in which users have to discriminate different stimuli, move their fingers in a free way to find and locate an object in a wider area of exploration and integrate all the perceived information to determine the position of the object. The study explores how users perform this haptic search task involving one or two fingers on a surface area. In order to carry out this research and overcome limitations of current hardware approaches to multi-point haptic surfaces, we used a setting consisting of a capacitive multi-touch screen and a general-purpose wearable vibrotactile device designed in our laboratory. The results indicate that using one finger in one hand shows to be more effective than using two fingers in either one or two hands in the task under study. Users showed higher confidence, lower exploration times, higher amount of right answers and higher exploration speed. This suggests that great efforts in providing independent multi-point haptic surface hardware could not be a priority for this kind of exploration task.