International Conference on Artificial Reality and TelexistenceEurographics Symposium on Virtual Environments (2023)
A. Campbell, C. Krogmeier, and G. Young (Editors)

PosterA Visual Approach to Pseudo Unseen Presencein the Metaverse Using HMD
Kenji Funahashi1and Yuzuki Matsunoo1

1 Nagoya Institute of Technology, Japan

Abstract
You may sometimes sense an unseen-presence when someone is behind you. We propose a novel method to show pseudopresence through visual perception using only a standard HMD. This goal is not to promote a clear perception of the fivesenses, but rather to somehow subconsciously perceive a sense of presence.
CCS Concepts• Human-centered computing → Interaction design; Empirical studies in interaction design;

1. Introduction
You may sometimes sense an unseen presence when someone isbehind you. Interaction in the metaverse has been increasing in recent years as living and working at home have become more commonplace. In the same the way that some information processedby the brain is subconscious, presence is one of them. Previousstudies show a presence-like sensation by humidity and water vapor [HKKT17], a part of sound emphasis [ZIK∗ 12], a quasi-static
electric field near CRT [SAS20], and an electrostatic field using
Van de Graaf generators [KK21]. These goals are not to promote aclear perception of the five senses, but rather to somehow subconsciously perceive a sense of presence. Hopefully these techniques
will be applied to the Metaverse. However, it is difficult to implement these methods into the home-use metaverse because they require special equipment or environments. In this study, we propose
a novel method to show pseudo presence through visual perception
using only a standard HMD.

Figure 1: Horizontal vision in; (left) real space, (right) HMD

2. A METHOD TO SHOW PSEUDO PRESENCE
The human visual field can be divided into a central vision, in
which the shape and color of objects can be clearly recognized, anda peripheral vision, in which the shape and color of objects cannot
be recognized. The peripheral vision has lower spatial resolution
and poorer hue perception compared to the central vision. However, the peripheral vision is more sensitive than the central vision
to the perception of motion and at low light levels, and information
can be processed unconsciously. Therefore, a light-colored, translucent silhouette of a human shape is superimposed at a position of,for example, 40 degrees in the peripheral vision area of the HMD(Figure 1) when a person appears behind to the left or right. The
silhouette should be displayed as transparent for as short a time as
possible so as not to be aware of it (Figure 2 and 3).
© 2023 The Authors.
Proceedings published by Eurographics - The European Association for Computer Graphics.
This is an open access article under the terms of the Creative Commons Attribution License, whichpermits use, distribution and reproduction in any medium, provided the original work is properly
cited.

Figure 2: Schematic depiction of pseudo presence

3. EXPERIMENTS
The effectiveness of the proposed method was verified through experiments using HMD; Oculus Rift (Figure 4). The silhouette transparency α was set in 10 different values from 0.005 to 0.050 atintervals of 0.005 (α = 0 is completely transparent and α = 1 iscompletely opaque, and the α is 0.040 in the Figure 3), the display
duration time t was set in 5 values from 1 to 5 at 1 second intervals, and there were 50 patterns in total. Each of the 10 subjects
was randomly assigned 25 patterns. Each pattern was assigned 5Kenji Funahashi & Yuzuki Matsunoo / A Visual Approach to Pseudo Unseen Presence in the Metaverse Using HMD

Table 1: Difference between P and V (P−V) for each α and t

Figure 3: View of visual pseudo presence in HMDt[s]α0.005
0.010
0.015
0.020
0.025
0.030
0.035
0.040
0.045
0.050

123450−0 = 0
1−0 = 12−0 = 21−0 = 12−2 = 03−1 = 2
4−0 = 43−2 = 1
1 − 4 = −3
2 − 3 = −1

0−0 = 00−0 = 00 − 2 = −22−1 = 1
1 − 3 = −2
3−1 = 23−1 = 22 − 3 = −1
2 − 3 = −1
1 − 3 = −2

1−0 = 12−0 = 22−1 = 14−0 = 41 − 2 = −1
3−1 = 23−2 = 1
1 − 4 = −3
0 − 5 = −50 − 5 = −5

3−0 = 32−0 = 22−1 = 13−1 = 22−1 = 1
1 − 4 = −3
2 − 3 = −1
0 − 4 = −4
0 − 5 = −50 − 5 = −51−0 = 1
2−0 = 21−1 = 02−2 = 00 − 5 = −51 − 4 = −31 − 3 = −20 − 5 = −51 − 4 = −30 − 4 = −4

Figure 4: Appearance of experimenttimes, there were 250 trials in total. The start time of the silhouettedisplay was randomly set from 3 to 8 seconds after the start of thetrial depending on the display duration, so that the timing of thesilhouette display was not predictable and one trial was completed
in 10 seconds. The direction of display was also random. Note that
there were no people around the subjects at the time of the experiment, and the actual presence of people did not affect the results.
Subjects were asked to play a three-shell game in which they kept
looking at a cup containing a ball to avoid looking at the silhouettein their central vision. After each trial, subjects reported the visibility of silhouette, direction of presence, and unseen presence itself.
For each pattern, count the following number of times.
V : the silhouette is visible
N : the unseen presence itself was not felt (invisible)
P : the direction of presence is correct (felt and invisible)
F : the direction of presence is false (felt and invisible)
Note that since the presence is not always felt and is not always
correct, the number N and F are not considered in this study. The
difference between P and V for each α and t combination is shownin Table 1 and Figure 5. The number P is relatively large and V isclose to zero when the transparency α is less than 0.020 and thedisplay time t is around 3 to 4 seconds, and when α is around 0.030
to 0.035 and t is less than 3. The dark silhouette is easily perceived
under consciousness even in the peripheral vision, but the shorter
display time may have stimulated reflexive perception. The lightsilhouette is consciously less recognizable in short display times,
but the slightly longer display time may have stimulated unconscious perception. The result suggests that a translucent silhouettedisplayed for a short time would be effective as a pseudo presence,around the transparency and time (α, t) from (0.035, 1) to (0.005, 4)
via (0.020, 3) in this experiment.
4. CONCLUSION
In this study, we proposed a novel method to represent pseudo presence in the metaverse using HMD. The body of pseudo presence isFigure 5: Graph of difference between P and V (P−V)

a human shape silhouette with a short display time and translucent
color. The experiments suggested that the silhouette is effective as
pseudo presence at appropriate display times and transparencies.
However, these times and transparencies would also depend on thebackground. In the future, we would like to consider the influenceof background type and color, and attempt to dynamically control
the display time and transparency.
Acknowledgment
This work is supported in part by JSPS KAKENHI Grant Number
JP20K11918 and JP23K11182.
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