Real-time haptic interactions occur under two exploration modes: active and passive. In this paper, we present a series of experiments that evaluate the main perceptual characteristics of both exploration modes. In particular, we focus on haptic shape recognition as it represents a fundamental task in many applications using haptic environments. The results of four experiments conducted with a group of 10 voluntary subjects show that the differences in motor activity between active and passive haptics ease the perception of surfaces for the first case and the perception of pathways for the latter. In addition, the guidance nature of passive haptics makes the pathway direction easy to recognize. This work shows that this last observation could find application in more challenging tasks such as navigation in space.

We report the results of a study on the learnability of haptic icons used as alerts or notifications in smartphones. The aim was to explore the feasibility of using haptic icons to create assistive technologies for people with visual impairments. We compared the performance and satisfaction of users with different visual capacities (visually impaired vs. sighted) and using different learning processes (with or without a reinforcement learning stage). The reinforcement learning stage improves the recognition rate in both types of users, although the improvement obtained by the visually impaired users is even better as their recognition rates become very similar to those obtained by the sighted users. Finally, it was observed that the better recognized haptic icons are those assigned to the most employed applications by the user.

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