  Pseudo-haptics techniques are interesting alternatives for generating haptic
perceptions, which entails the manipulation of haptic perception through the
appropriate alteration of primarily visual feedback in response to body
movements. However, the use of pseudo-haptics techniques with a motion-input
system can sometimes be limited. This paper investigates a novel approach for
extending the potential of pseudo-haptics techniques in virtual reality (VR).
The proposed approach utilizes a reaction force from force-input as a
substitution of haptic cue for the pseudo-haptic perception. The paper
introduced a manipulation method in which the vertical acceleration of the
virtual hand is controlled by the extent of push-in of a force sensor. Such a
force-input manipulation of a virtual body can not only present pseudo-haptics
with less physical spaces and be used by more various users including
physically handicapped people, but also can present the reaction force
proportional to the user's input to the user. We hypothesized that such a
haptic force cue would contribute to the pseudo-haptic perception. Therefore,
the paper endeavors to investigate the force-input pseudo-haptic perception in
a comparison with the motion-input pseudo-haptics. The paper compared
force-input and motion-input manipulation in a point of achievable range and
resolution of pseudo-haptic weight. The experimental results suggest that the
force-input manipulation successfully extends the range of perceptible
pseudo-weight by 80\% in comparison to the motion-input manipulation. On the
other hand, it is revealed that the motion-input manipulation has 1 step larger
number of distinguishable weight levels and is easier to operate than the
force-input manipulation.
