Dynamics of exploration in haptic search*

Haptic search is a common every day task. Here we characterize the movement dynamics in haptic search. Participants searched for a particular configuration of symbols on a tactile display. We compared the exploratory behavior of the fingers in proximity to potential targets: when any of the fingers encountered a potential target, there was higher probability that subsequent exploration was performed by the index or the middle finger. At the same time, the middle and the index fingers dramatically slowed down. Being in contact with the potential target, the index and the middle finger moved in around a smaller area than the other fingers, which rather seemed to move away to leave them space. Our results corroborate a previous hypothesis [1] that haptic search consists of two phases: a process of target search using all fingers, and a target analysis using the middle and the index finger, which might be specialized for fine analysis.