With the increasing use of immersive simulators in surgical training, there is an emerging emphasis on providing realistic haptic feedback. Although haptic feedback is recognized as necessary for surgical skill acquisition, its role in transferring those skills to real-life situations still needs to be explored. Our study aims to investigate the impact of haptic feedback on basic microsurgery skill acquisition, transfer, and retention, as well as on the user experience during VR training. An immersive simulator was developed to practice a microgrid task under magnification with and without haptic feedback. A similar physical setup with a binocular microscope was also designed to measure skills transfer to the real world. Thirty-three volunteers ($N=33$) were randomly divided into three participant groups: the haptic feedback group (HG), the no-haptic feedback group (NG), and the control group (CG). All participants performed the task on the physical setup during the pre-post-retention tests. After the pre-test, the first two groups performed six training trials on the immersive simulator, with the HG group receiving haptic feedback while performing the task. The control group did not receive any training. The results show that the HG and NG groups significantly improved their learning curve during training, with no significant differences between them. On the Other hand, the haptic feedback led to significantly higher usability and possibility of examination scores than those without haptic feedback. Finally, all the groups improved their time performance on the physical simulator. In addition, the haptic group participants showed a more significant gain in performance in terms of accuracy and error rates. These findings confirm the effectiveness of immersive environments combined with haptic feedback as a valuable training tool, facilitating the transfer of technical skills to realworld applications. Moreover, the results indicate that haptic feedback can also improve the user experience in immersive surgical simulators.

Mastering motor skills requires performing the task unconsciously with great speed and accuracy. This is acquired slowly through practice over time. Nonetheless, in domains such as surgery, the training of these skills in the field introduces safety, ethical and economic issues. In this context, immersive VR technologies offer the possibility to recreate real-world situations and allow the trainees to improve their skills in a safe and controlled environment. However, the design of such systems raises new research questions, such as how to represent the user in the virtual environment, and whether this representation can influence motor skills automaticity. In this work, we focus on how the user's hand representation can impact the training of tool-based motor skills in immersive VR. To investigate this question, we have created a VR simulator for training a tool-based pick and place task, and conducted a user study to evaluate how the user's hand visualization can influence participants' learning performance after a two-week training period. For that purpose, two groups of participants were trained in the VR simulator under one of the two experimental conditions: the presence and the absence of their virtual hands' representation, while a control group received no training. The results of the study show that training on the VR simulator improves the participants' motor task performance when compared with the control group. On the other hand, no difference was observed between the two training groups. This suggests that the user's hand visualization does not always impact tool-based motor tasks training in immersive VR simulators. Indeed, for short-term motor training there was no difference in performance between having a partial embodiment of the user's hands and only the tools representation.

Immersive VR technologies offer versatile training tools by recreating real-world situations in a virtual and safe environment and allowing users to have a first-person experience. The design of such training systems requires defining the most critical components to simulate, and to what extent they can be simulated successfully. One open research question for designing such systems is how to represent the user in the virtual environment, and which is the added value of this representation for training purposes. In this work, we focus on how the user's hand representation in an immersive virtual environment can impact the training of tool-based motor skills.To investigate this question, we have designed a VR trainer for a simple tool-based pick and place task. A user experiment was conducted to evaluate how the movements of the users' real hand representation influence their performance and subjective experience in the virtual environment. For that purpose, the participants performed the task on the VR simulator with two conditions: the presence or absence of their animated virtual hands representation. The results of this study show that, although users prefer to have a visual representation of their hands, they achieved similar and correlated performance in the VR system regardless of the hand representation condition. These results suggest that the presence of the user's hand representation is not necessary when performing a tool-based motor skill task in a VR trainer. These findings have practical implications for the design of VR simulators for training motor skills tasks since adding users' hand representation may require cumbersome and expensive additional devices.

Virtual Reality simulators are increasingly used for training novice surgeons. However, there is currently a lack of guidelines for achieving interaction fidelity for these systems. In this paper, we present the design of two navigation techniques for a needle insertion trainer. The two techniques were analyzed using a state-of-the-art fidelity framework to determine their levels of interaction fidelity. A user study comparing both techniques suggests that the higher fidelity technique is more suited as a navigation technique for the needle insertion virtual trainer.