  Retargeting methods that modify the visual representation of real movements
have been widely used to expand the interaction space and create engaging
virtual reality experiences. For optimal user experience and performance, it is
essential to specify the perception of retargeting and utilize the appropriate
range of modification parameters. However, previous studies mostly concentrated
on whether users perceived the target sense or not and rarely examined the
perceptual accuracy and sensitivity to retargeting. Moreover, it is unknown how
the perception and performance in hand-retargeted interactions are influenced
by multisensory feedback. In this study, we used rigorous psychophysical
methods to specify users' perceptual accuracy and sensitivity to
hand-retargeting and provide acceptable ranges of retargeting parameters. We
also presented different multisensory feedback simultaneously with the
retargeting to probe its effect on users' perception and task performance. The
experimental results showed that providing continuous multisensory feedback,
proportionate to the distance between the virtual hand and the targeted
destination, heightened the accuracy of users' perception of hand retargeting
without altering their perceptual sensitivity. Furthermore, the utilization of
multisensory feedback considerably improved the precision of task performance,
particularly at lower gain factors. Based on these findings, we propose design
guidelines and potential applications of VR hand-retargeted interactions and
multisensory feedback for optimal user experience and performance.
