\section{Conclusion}
\label{conclusion}

This paper presented two human subject studies aimed at better understanding the role of visuo-haptic rendering of the hand during virtual object manipulation in OST-AR.
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The second experiment compared, in the same two manipulation tasks as before, sixteen visuo-haptic renderings of the hand as the combination of two vibrotactile contact techniques, provided at four different delocalized positions on the hand, and with the two most representative visual hand renderings established in the first experiment, \ie the skeleton hand rendering and no hand rendering.
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Results show that delocalized vibrotactile haptic hand rendering improved the perceived effectiveness, realism, and usefulness when it is provided close to the contact point.
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However, the farthest positioning on the contralateral hand gave the best performance even though it was disliked: the unfamiliarity of the positioning probably caused the participants to take more effort to consider the haptic stimuli and to focus more on the task.
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The visual hand rendering was perceived less necessary than the vibrotactile haptic hand rendering, but still provided a useful feedback on the hand tracking.

Future work will focus on including richer types of haptic feedback, such as pressure and skin stretch, analyzing the best compromise between well-round haptic feedback and wearability of the system with respect to \AR constraints.
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As delocalizing haptic feedback seems to be a simple but very promising approach for haptic-enabled \AR, we will keep including this dimension in our future study, even when considering other types of haptic sensations.
