# Touch Matters: The Impact of Physical Contact on Haptic Product Perception in Virtual Reality
## 2 Materials and Methods  
### Experimental Study  
The experiment conducted for this research received the formal approval of the ethics committee named the Comision Deontologica of the Universitat Jaume I institution, with the approval code CD/102/2021.  
In order to check our hypotheses, an experiment was designed in which each participant viewed and interacted with the same product, which was presented by five different means: real setting (R), virtual reality (VR), virtual reality with passive haptics (VRPH), non-interactive 3D animation in a looped video (V), and 360-degree rotatable image or interactive 3D image (3 Di). Two allowed the product to be touched (R, VRPH), and three did not (VR, V, 3 Di). The order of viewing sequence was alternated to balance any possible resulting effects.  
A chair was selected for the present study for two reasons: it is a usual product found in the domestic habitat and is, thus, known by users; and it presents enough formal characteristics for users to evaluate different aspects. To help users pay attention only to the product, it was placed in the middle of an empty white-walled room. The scene was prepared in five different presentation means, each inside a room (Figure 1).  
1. Room 1 (R). A square set was built with white panels that simulated the walls of a room, and the real chair stood in the middle. White light was vertically projected onto the chair from the ceiling. Each panel measured 2.60 m long, except for one that measured only 2 m to leave an opening so that participants could enter and leave the setting. All the white panels were 2 m high. The participants could move around the chair, touch it, and sit on it.
2. Room 2 (VR). The chair and Room 1 setting were modelled and rendered with the same details, textures, and lighting. It was presented in VR. The participants could move around the chair, but not touch it or sit on it because there was no physical chair in this room.
3. Room 3 (VRPH). The scene was the same as in Room 2 and was presented in VR, but a physical chair was added by synchronizing its position with the viewed 3D model so that the participants could touch the chair and sit on it. For a correct use of passive haptics in VR, two criteria must be met: similarity between haptic proxies and virtual objects in both material and geometrical properties, and co-location, i.e., both must share the same position and alignment [44; 45].
4. Room 4 (V). The same scene was rendered on a tablet screen. The chair and the scene automatically turned at constant speed in relation to the vertical axis that passed through the center of the chair. The scene took 12 s to turn 360 degrees. The participants could watch the animation, but could not interact with it.
5. Room 5 (3 Di). The same scene rendered in Room 4 was created and presented on another tactile screen with the same characteristics. In this case, the participants could touch the screen and slide their fingers to the right or left, turning the scene around  
Figure 1: The five rooms used during the experiment.  
the vertical axis that passed through the center of the chair. This allowed them to view the chair from multiple angles.