Optimal Exploration Strategies in Haptic Search

In this study, we have investigated which strategies were optimal in different haptic search tasks, where items were held in the hand. Blindfolded participants had to detect the presence of a target among distractors while using predetermined strategies. The optimal strategy was determined by considering reaction time and error data. In the search for salient targets, a rough sphere among smooth or a cube among spheres, parallel strategies were optimal. With non-salient targets, the results were different. In the search for a sphere among cubes, a parallel strategy was effective, but only if the fingers could be used. In the search for a smooth sphere among rough, only a serial strategy was successful. Thus, the optimal strategy depended on the required perceptual information.