# Exploring the Effect of Virtual Environments on Passive
## 5 Experiment for Effects on Passive Haptic Perception  
In our paper, we proposed the effects of passive haptic perception in the immersive VR environment and focused on transformation conditions of a virtual object related to its real counterpart (or physical prop). We ran three comparative experiments (i.e., position, rotation, and scale) to evaluate the participant's perception, as judged by the same range between the real and the virtual environments with respect to passive haptics.  
We installed the HMD, the actual cube, and the tracking system. In the initial setup, the virtual cube was visualized to appear with the same size, position, and orientation as the real one. Then, we investigated how participants responded to three conditions with five steps in each condition (see Table 2). We introduced the purpose of our research study and gave instructions to the participants. Then, the within-subject experiment was conducted in a predetermined random order with a total of 15 steps, whereby an operator behind the curtain configured the experimental conditions. In each step of the experiment, the participant was asked to touch the virtual cube placed on a virtual desk. Twenty-four paid participants with an average age of 26 years participated in our experiment. The age range was between 20 and 34 years old. Considering the gender of participants, 33% were females (8 women) and 67% were males (16 men). All participants had at least one experience with an immersive VR system prior to our experiment; most participants (20 people) were playing mobile games regularly. Fortunately, all participants were right-handed, and we did not have to change the virtual hand representation.  
At each step, the participant was asked to describe the difference in perception between the virtual object and a real prop with respect to transformation. Here, participants who denoted the presence or absence of a difference were also asked about the degree after carrying out the task. The degree was measured using a questionnaire with a 100-point scale, where a score of 0 denoted perfect matching between two objects of different environments (e.g., real or virtual), while a score of 100 denoted complete inconsistency. Here, to more accurately analyze the precise difference, in the experiment, we used a 100-point scale.  
Figure 7 shows the number of participants who evaluated perception differences according to transformation factors. In the position factor test condition, many participants thought that there was a difference between the real and virtual environments by distance error. In the case of the rotation factor, participants distinguished a difference between the two environments more clearly than by other factors. In terms of the scale factor, there were similar results to position factors, in that people highlighted differences according to the size of the virtual object.  
Figure 6: An example of scale perception in the passive haptic environment: step 1 with a small size compared to the actual object (**left**), and step 3 with the same size (**right**).  
Figure 8 shows the survey results regarding the degrees of perceived differences between the virtual object and the real one in terms of transformation. The overall trend was similar to the participant's perception of the difference. In the case of scale, our experimental study showed that participants had certain tendencies. A pairwise comparison using two-sample \(t\)-tests (small-size group or large-size group) showed a significant effect in the statistical analysis (\(t\)(46) = 6.90, \(p\) < 0.05). Here, we found beneficial results in the guidelines to install virtual reality systems. Details are provided in Section 6.