Perception of a Spatial Implausibility Caused by Seamless Covert
Mathieu Lutfallah
, Dylan Cernadela Pires, Valentina Gorobets
and Andreas Kunz
Innovation Center Virtual Reality, ETH Zurich, Switzerland
Locomotion, Walking, Redirection, Human Perception.
This paper investigates human perception of spatial implausibility through seamless teleportation in circular
and hexagonal closed-loop corridors. Spatial implausibility refers to virtual spaces that deviate from New-
tonian Euclidean geometry rules, while seamless teleportation involves changing the user’s position in the
virtual world without their awareness. In this work, the impression of implausibility is generated by subtle
teleportation of the user within these corridors, thereby allowing them to unconsciously skip certain sections of
them. Different levels of this “implausibility” are presented by varying the percentage of skipping within these
corridors, specifically 0%, 15%, and 30% of the corridor’s overall length. These implausibilities are assessed
through a within-subject study on naive participants to determine their perception of spatial implausibility. Our
findings indicate no significant difference in the detection rates between the two corridor shapes. Interestingly,
most participants interpreted the manipulation as a change in the environment’s shape or size while only few
could perceive the teleportation and the skip. This paves the way for future research to leverage this technique
for subtle spatial manipulation.
A crucial and integral aspect of any virtual reality
(VR) experience is the locomotion technique used
to navigate virtual environments (VEs). Immersive
and engaging VEs come to life through the seam-
less movement and exploration through effective lo-
comotion techniques. By providing users with intu-
itive means to traverse and interact with VEs, loco-
motion systems enhance the sense of presence and
empower individuals to fully immerse themselves in
these VEs. From walking-in place (Wendt et al.,
2010) and on treadmills (Iwata, 1999) to point-and-
teleport methods, joystick navigation, and real walk-
ing approaches, a wide range of locomotion tech-
niques have emerged, catering to diverse user pref-
erences and optimizing the overall VR encounter.
Among these techniques, teleportation remains one of
the most commonly used. It can be achieved in var-
ious ways, allowing the user to either translate or to
both translate and rotate. Additionally, teleportation
can be employed with or without the user’s knowl-
edge. For example, the user might be transported by
a bird to a new location or moved to another section
of the corridor that appears identical to their current
position, without realizing it. In such cases, while the
immediate surroundings remain the same, everything
beyond the user’s current field of vision is different.
This method would constitute seamless teleportation.
Real walking, as a locomotion technique, stands
out for its potential to enhance presence and immer-
sion in the VE (Usoh et al., 1999; Cherni et al., 2020)
and provides a more simple, straightforward and nat-
ural user experience compared to other locomotion
techniques. It allows users to physically move within
the virtual space, providing a high level of control
precision and minimizing the occurrence of motion
sickness. However, real walking has one significant
drawback, since it requires a considerable amount of
physical space, making it impractical for small track-
ing areas commonly found in home-based VR setups.
Here, redirection techniques come into place that al-
low using smaller physical environments for navigat-
ing large VEs.
Redirection Techniques: take advantage of human
perceptual limitations and enable users to navigate
large VEs while keeping them within the bounds of
their tracking space. These techniques can be ap-
Lutfallah, M., Pires, D., Gorobets, V. and Kunz, A.
Perception of a Spatial Implausibility Caused by Seamless Covert Teleportation.
DOI: 10.5220/0012573500003660
Paper published under CC license (CC BY-NC-ND 4.0)
In Proceedings of the 19th International Joint Conference on Computer Vision, Imaging and Computer Graphics Theory and Applications (VISIGRAPP 2024) - Volume 1: GRAPP, HUCAPP
and IVAPP, pages 380-389
ISBN: 978-989-758-679-8; ISSN: 2184-4321
Proceedings Copyright © 2024 by SCITEPRESS Science and Technology Publications, Lda.
plied either to the user or to the VE. For example,
(Langbehn et al., 2020) seamlessly integrated redi-
rection into a game, where the world was turned
around the players while they were concentrating on
a task, i.e. making whipped cream. Various redirec-
tion techniques exist, and efforts have been made to
classify them. In the taxonomy proposed by (Suma
et al., 2012a), redirection techniques are separated
based on their geometric flexibility versus the like-
lihood that they will be noticed by the users. Redi-
rection techniques are divided into repositioning and
reorientation. Repositioning techniques modify the
mapping from points in the real world to the virtual
world to condense a larger VE into a compact physi-
cal environment. Reorientation techniques rotate the
user’s heading away from the boundaries of the phys-
ical space. Concerning the noticeability, the taxon-
omy distinguishes between subtle and overt methods.
Finally, redirection techniques can be implemented
in a discrete or continuous manner. Discrete tech-
niques are applied instantaneously, while continuous
techniques are applied over time. Another taxon-
omy was presented by (Vasylevska and Kaufmann,
2017a) where they distinguish 4 categories of algo-
rithms “Basic Reorientation”, “Rendering Manipula-
tion”, “Sense Manipulation”, and “Scene Manipula-
Redirection of a user can be achieved by tech-
niques that modify the VE. Such techniques rely on
impossible spaces that defy conventional logic but
also challenge Newton’s laws of motion and the fun-
damental principles of geometry. An example of
such spaces are overlapping architecture (OA) is a
technique that optimizes tracking space utilization
by overlapping spaces. One example are overlap-
ping neighboring rooms where the goal is to create
the illusion that these rooms occupy separate areas
while, in reality, they share the same physical space.
The overlap occurs when the user traverses a corri-
dor and the wall separating the two rooms shifts. The
maximum allowable overlap before users perceive it
was explored by (Suma et al., 2012b). Additionally,
“Change Blindness” (Suma et al., 2011) refers to the
technique of altering the position of objects within a
space when the user is not noticing it. This allows for
the manipulation of the space and enables the reuse of
the physical area for various segments of the VE.
Prior studies investigating the detection of redirec-
tion thresholds (Suma et al., 2012b; Vasylevska and
Kaufmann, 2015; Steinicke et al., 2010) have primar-
ily involved non-naive participants who were already
familiar with the concept of the redirection applied.
Moreover, existing research papers that analyze the
detection of impossible spaces by the users have pre-
dominantly used a specific implementation involving
two overlapping rooms. However, there is a lack of re-
search exploring alternative methods relying on seam-
less teleportation to generate such spatial implausibil-
ities. Lastly, the studies that have incorporated por-
tals and teleportation (Koltai et al., 2020; Lochner and
Gain, 2021) to create spacial implausibility have not
examined how users perceive these spaces, particu-
larly in terms of perception or detection.
In this work, we focus on the perception and cog-
nitive map in a new type of spatial implausibilities
where the users skips certain parts of the VE. As
shown in Figure 1, omitting specific segments of a
corridor enables spatial manipulation, thereby reori-
enting the VE. This technique allows moving por-
tions of the VE previously outside the physical space
boundary into it. This is in contrast to previous imple-
mentations of portals which allowed reusing the same
physical space for different segments of the VE. This
is highlighted in Figure 1 by showing that the small
room shown by the small rectangle could have been
colliding with an obstacle but after the reorientation
the room could be explored. The contributions of this
paper are as follows:
Presentation of a new type of subtle reorientation
technique relying on corridors and teleportation,
Investigation of the perception of the users of such
a technique based on various levels of implausibil-
ity and different layouts.
Figure 1: Illustration of spatial manipulation using portals,
by teleporting the user in the corridor between the two rect-
angles (left image) the environment changes orientation as
seen in yellow (right image).
2.1 Perception for Scene Manipulation
A well-known concept of generating spatial implausi-
bilities is named “impossible spaces”, which was in-
troduced by (Suma et al., 2012b). Here the threshold
metric was the overlap between neighboring rooms.
The study concluded that reasonably small virtual
rooms could overlap by up to 56% before users de-
Perception of a Spatial Implausibility Caused by Seamless Covert Teleportation
tected it. Moreover, based on a qualitative experiment
it was observed that participants who are naive to the
manipulation of impossible spaces tend to experience
a more compelling illusion. Other researchers took
that same spatial compression approach and did fur-
ther research on the influence of path complexity in
overlapping space detection (Vasylevska and Kauf-
mann, 2015). The research gap they addressed was
the lack of knowledge on the effect of different virtual
architectural layouts on the perception of such over-
lapping spaces. There findings suggest that path com-
plexity is a variable that has to be taken into consider-
ation when trying to optimize spatial compression. In
a later study by (Vasylevska and Kaufmann, 2017b),
they explored the influence of layout properties on
the perception of impossible spatial arrangements.
Their study aimed to analyze various parameters as-
sociated with the path connecting two overlapping
rooms. These parameters encompassed the “number
of turns, relative door positions, sequences of clock-
wise and counterclockwise turns, as well as symme-
try and asymmetry”. Among other results, they found
that the absence of landmarks made it harder for par-
ticipants to orient themselves in space. This in turn
is more beneficial for spatial compression. A more
recent study (Eppl
ee and Langbehn, 2022) examined
the effects of using a minimap during exploration of
a VE featuring impossible spaces. (Ciumedean et al.,
2021), on the other hand, tested the effects of different
layouts in impossible spaces: “open rooms”, where
rooms are not separated by walls but only by small
objects to prevent direct crossing from one room to
another without using the corridor; “open corridors”,
characterized by partial walls that allow the user to
view the outside space; and “total inclusion”, the stan-
dard condition. The focus was on how these layouts
impact the detection threshold.
2.2 Teleportation as a Locomotion
Various studies (Freitag et al., 2014; Langbehn et al.,
2018) compared the use of teleportation as a loco-
motion technique in navigating virtual environments.
Another work by (Langbehn et al., 2018) compared
teleportation with redirected walking techniques, fo-
cusing on cognitive map building, cybersickness, and
user preferences. In their studies, teleportation is ini-
tiated through deliberate user action, as opposed to
being seamlessly integrated. Other research (Bruder
et al., 2009) has explored combining teleportation
with techniques like portals and redirected walking
enhancing the exploration in large virtual environ-
ments. Teleportation can be implemented in two
distinct ways: partial concordance, where it is used
solely for translational movements, and full discor-
dance, where it is employed for both rotation and
translation. The effects of these methods have been
investigated on spatial updating and piloting (Kelly
et al., 2020). Furthermore, a detailed literature re-
view is provided in (Prithul et al., 2021), comparing
teleportation techniques with alternative locomotion
methods. This review also encompasses a discussion
of various approaches to implementing teleportation.
2.3 Spatial Implausibility Using
Seamless Teleportation
Another interesting way of implementing spatial im-
plausibility is by changing the user’s position through
instantaneous and seamless teleportation. The work
by (Koltai et al., 2020) presented a method for creat-
ing scaleable overlapping architecture in VR by “pro-
cedurally generating tile-based mazes that seamlessly
teleport the user using portals”. To implement this
unnoticeable teleportation, they used portals on spe-
cific locations in the virtual maze. These portals con-
sisted of a rendered plane on which the corresponding
part of the next maze element was displayed. When
the users crossed the portal threshold they were tele-
ported to the maze element that was displayed on the
portal itself. Like this, the users could not notice the
teleportation and an illusion of continuity was cre-
ated. Similarly, (Overdijk, 2023) utilized the same
method, combining it with the game’s narrative to
guide the user, enabling continuous walking in the
virtual world. In the same fashion, portals were intro-
duced by (Lochner and Gain, 2021). They analyzed
different locomotion techniques in impossible spaces,
and used portals and teleportation. In their work, they
used pairs of portals to travel between different sub-
spaces of the VE. The portal pairs all had the same lo-
cal position and orientation so that the user’s rotation
would not need to be altered when teleporting. Only
the users’ position had to be translated to the corre-
sponding subspace. Through this, they were able to
compress several virtual rooms into the space of one
for their experiments.
The aforementioned studies primarily concen-
trated on users’ perception of implausible spaces
while navigating spaces featuring impossible geome-
tries and change blindness. In contrast, other re-
search has focused on teleportation as the primary lo-
comotion technique. However, only a few of these
have seamlessly integrated teleportation. These in-
stances primarily utilized teleportation to overlap vir-
tual spaces rather than to manipulate them. Seamless
teleportation could enable the alteration of the VE’s
HUCAPP 2024 - 8th International Conference on Human Computer Interaction Theory and Applications
(a) Circular Corridor. (b) Hexagonal Corridor.
Figure 2: Illustration of the two closed-loop corridor lay-
orientation in relation to the physical space. This gap
in research has motivated the current work, where
we explore combination of teleportation and corri-
dors and the noticeability of implausible spaces. This
research will explore how different corridor shapes,
specifically circular and angular with corners, affect
the user’s cognitive map. Additionally, it will ex-
amine the user’s perception of seamless teleportation,
particularly how skipping certain portions of the cor-
ridors influences this perception.
Since we want to investigate how users would detect
the implausibility of the space relying on teleporta-
tion, we decided to use two closed-loop corridors in
which participants could walk. One corridor had a
circular shape, and the other a hexagonal one. The
corridors each consisted of a white inner and outer
wall with grey ground and ceiling. The decision to
intentionally omit textures in the scenes was made in
order to avoid visible landmarks, minimize distrac-
tions, and thereby reduce the number of variables that
needed to be taken into account. The size of the corri-
dors was chosen to fill the available physical tracking
space (7m × 9m) with a height of 2.5m. This leads
the corridors to have a width of 1.1m. We also added
a start sign together with a red arrow, positioned on
the inner wall, as a reference point for the users and
to indicate the direction the participant would need to
walk. The sign is also the cue for the user that he is
back to the initial position. Figure 2 shows the corri-
dors with the ceiling removed.
3.1 Seamless Teleportation Design
To create an implausible space within the corridors,
we implemented portals in conjunction with telepor-
tation. The idea was to seamlessly teleport the users
walking in the corridors from one point in the corri-
dor to another point in the corridor. This has the effect
that users skip a section of the corridor and therefore
reach the starting position faster, which would not be
possible in a real-world scenario. The objective of this
approach is to make users believe that they are walk-
ing along the entire corridor while, in reality, they are
skipping a certain section of it. If the users do not no-
tice this illusion, then the implausibility of the space
is successfully unnoticed and the orientation of the
physical space is changed. We included three levels
of teleportation for each corridor shape which would
later represent different experiment conditions. The
first condition is the Zero condition where the users
are not teleported at all while walking along the cor-
ridor. We represent these conditions as C0 and H0,
where C represents the circular corridor, H represents
the hexagonal corridor and 0 represents that no sec-
tions have been skipped in the corridor. The follow-
ing conditions use the same terminology. In condi-
tions C1 and H1 a sixth of the corridor is skipped
and in conditions C2 and H2 a third of the corridor
is skipped.
To ensure seamless teleportation, we employed
instantaneous repositioning of the user. We imple-
mented a collision plane located at the end of the first
section of the corridor. When the user walks through
this plane, it triggers the repositioning of the player.
The corridor the user is teleported to was already ro-
tated to a specific degree around its z-axis. The ad-
vantage of using a pre-rotated corridor as the destina-
tion instead of teleporting the player within the same
corridor lies in the fact that we only need to trans-
late the player’s position, without requiring a change
in rotation. Implementing a rotation change of the
player would be considerably more challenging. Con-
sequently, this means that in conditions C1 and H1 the
corridor where the user is teleporting to is rotated by
and for conditions C2 and H2 it is rotated by 120
illustrated in Figure 3.
Portals are generally 2D planes on top of which
the VE is rendered. They are usually placed on walls
or corridor endings where the architectural overlap
of the VE would happen. Consequently, by walk-
ing through the portals, together with teleportation, a
seamless transition from one VE to another is created.
Users perceive this as exploring a new VE, yet they
are reusing a space of the physical tracking space.
We used stencil buffers to create portals which ren-
der parts of a VE that we want to see while hiding the
parts that we do not want to see. The stencil buffer
is a dedicated buffer within the shader that can de-
cide if a pixel of an object is drawn or not. To de-
cide which pixels are to be drawn and which are not,
we can assign certain reference values to objects us-
ing the stencil buffer. By doing a so-called “stencil
Perception of a Spatial Implausibility Caused by Seamless Covert Teleportation
(a) No skip. (b) Skip of 16.7%.
(c) Skip of 33.3%.
Figure 3: Implausible space implementation for the hexag-
onal corridors. The green bars indicate the position of the
portals. The patterned sections specify the possible spatial
compression achieved by each condition. The same princi-
ples apply to the circular corridors.
test” the stencil buffer then compares the values of
two objects. If the values coincide the pixels of the
object can be chosen to be drawn, if not the pixels are
discarded. This technique helps us create seamless
transitions between different VEs. To implement the
stencil buffer portal we first need to create two sepa-
rate VEs within the same scene in Unity. One is the
VE where our user will be starting and the other is the
VE where he will be teleported to.
3.2 Hardware and Software
The VE was developed using the Unity engine, and
the Meta Quest 2 was used as the headmounted dis-
play (HMD) for presenting the VE during the user
study. The HMD utilizes an LCD panel with a res-
olution of 1832 × 1920 per eye at a frame rate of up
to 120Hz, featuring a horizontal field of view (FOV)
of around 104
and a vertical FOV of 98.2
. To pre-
vent participants from peeking through the gap be-
tween their nose and the HMD we installed a little
paper flap. The reason was that we wanted to prevent
the users to be able to orient themselves on the track-
ing space. The VE was streamed from a PC through
SteamVR, the PC had a GeForce RTX3090 graphics
card paired with a 10
generation Intel Core i9 CPU.
To develop our VE and to conduct our user study,
we utilized the Unity game engine (editor version
2019.3.19f1) together with the SteamVR plug-in,
which enables us to make VR applications which can
be directly run on the PC and also streamed to other
HMD, like in our case. Since Unity is limited in its
ability to create custom shapes and 3D objects we uti-
lized the Unity package called ProBuilder. This pack-
age is a 3D modelling and design tool which allows
users to create simple geometries
Prior to developing our user study, it was necessary
for us to determine the hypotheses we aimed to vali-
date. This allowed us to design our user study in ac-
cordance with these hypotheses. We decided on the
following hypotheses:
Hypothesis 1: Implausible space detection in-
creases if more sections of a closed-loop corridor
are skipped,
Hypothesis 2: Implausible space detection is
higher for closed-loop corridors with sharply
curved paths compared to smooth curved paths.
Our first hypothesis is straightforward since it is nat-
ural to expect users to notice the implausible space if
the changes are more drastic. In our second hypothe-
sis, we assume that sharp corners can be used as land-
marks (Vasylevska and Kaufmann, 2017b) to help the
users to orient themselves in space and thus help them
understand the spatial impossibility induced by the
Participants for both studies were recruited from
the university community. The sole criterion for par-
ticipation was the ability to walk, ensuring a broad
and accessible participant pool. Prior to commenc-
ing the experiments, we refrained from disclosing the
objective of the user studies in order to prevent par-
ticipants from actively seeking hints about the redi-
rection technique. Each participant was required to
provide their informed consent by signing a form.
Subsequently, the user began by completing question-
naires on demographics and the Simulator Sickness
Questionnaire (SSQ). They were then introduced to
the hardware in the SteamVR room, where they could
walk around and familiarize themselves with the sys-
tem. The user study procedure is shown in Figure 4.
The study then commenced, and the VE featuring
the corridors was launched. The participants started at
the start position in the corridor and were then told to
walk along it until they reach the start position again
shown by the start sign. Following each corridor ex-
perience, participants were presented with a simple
transition scene consisting of a wooden floor and sky.
They were instructed to follow a floating hand on
the screen, controlled by the experimenter, until in-
structed to stop. This procedure was conducted while
1, accessed on
HUCAPP 2024 - 8th International Conference on Human Computer Interaction Theory and Applications
the participant wore the head-mounted display. The
dual purpose of this approach was to disrupt the par-
ticipant’s spatial orientation within the tracking en-
vironment and prevent them from seeing their final
position in the physical space. Additionally, it facili-
tated repositioning the participant to the starting point
for each corridor iteration. This procedure was con-
sistently repeated for each corridor. Each participant
had in total two series of walking. In each series, the
participant had to walk through three different corri-
dor conditions of the same corridor shape. Half of
the participants started with the circular corridors and
half of them started with the hexagonal corridors. Af-
ter each series, the participant had to execute a draw-
ing task where he had to draw the virtual environment
where he walked. In the walking series, the sequence
of skip levels within the corridors was predetermined
in a counterbalanced order to ensure that each con-
dition occurred uniquely. Consequently, some users
might first experience a 33% skip, while others could
begin with no skip or a 16% skip. The purpose behind
this was to prevent learning effects and to be able to
analyze different corridor conditions.
After the study, the true purpose of the user study
was revealed, and we proceeded to explain the par-
ticipants how the corridors operated and provided an
explanation of the potential of spatial implausibil-
ity techniques. Subsequently, users were requested
to provide informal feedback regarding their impres-
sions of the manipulation.
4.1 Drawing Task
In the drawing task, participants had to draw the floor
plans of the three corridors they have just walked
along. Additionally, they had to indicate on each cor-
ridor drawing the “START” position and to try draw-
ing the corridors to scale. Drawing to scale meant
that if they perceived certain corridors to be smaller or
larger than others, they had to indicate it by drawing
larger or smaller corridors or alternatively describe it
with words. It is important to state that participants
were only told about the drawing task after walking
the corridor to prevent participants from focusing un-
naturally much on the corridor layout. The imple-
mentation of a counterbalanced user study, where par-
ticipants were equally exposed to commencing with
either the hexagonal or the circular condition, con-
tributed to neutralizing potential biases of the results.
Participants were instructed to draw the corridor floor
plans into boxes by the order they walked them. The
boxes contained a grid to help the participants with
their drawings and to make it easier to draw them to
scale. To extract meaningful data from the drawings
of the participants, we evaluated the drawings by two
measures and compared them to the actual condition
they were supposed to represent.
In order to assess whether participants detected
the implausibility of the spaces, we searched for corri-
dors that were either not closed or had additional start
or stop points drawn. Drawing an non-closed corridor
indicated that the users were aware that they have not
walked a full round. The same holds true for draw-
ing two separate start signs since changing the start-
ing sign to a different section in the corridor would
have the same effect as teleporting the player. Exam-
ples of non-closed-loop corridor drawings and dou-
ble start positions can be seen in Figure 5. The other
measure we evaluated was if the participant drew the
corridors within a series in different sizes or shapes
(SoS), compared to each other. Our reason was that
if they did so, they have not detected the implausible
space but they still detected a change going from cor-
ridor to corridor. Drawings, where only one change
in SoS occurred, were also counted as a detection. If
no change in SoS was detected, we counted it as no
From the 25 participants enrolled in our user study, 16
(64%) were male, while 9 (36%) were female. The
age distribution spanned from 16 to 30 years, with an
average age of 21.76 ± 2.69 years. The participants
consisted of 20 students and 5 non-students. More
than half of the participants (52%) reported having
between zero and ve hours of previous VR experi-
ence. Six participants had no experience, 3 partici-
pants had between 20 and 100 hours of experience,
2 participants had between 5 and 20 hours of experi-
ence, and 1 participant had over 100 hours of experi-
ence. The mean SSQ total difference prior and after
the user study was 1.65 ±9.58. Analysis of the SSQ
responses, administered both before and after the user
study, indicated no significant variance among partic-
ipants. Consequently, no participant required exclu-
sion from the study.
5.1 Drawing Task Results
From all participants, four did neither detect the im-
plausibility of the space space nor a change in the SoS
of the corridors. Two participants noticed both, the
implausible space and a change in SoS. The rest of
the participants detected at least either of those.
The overall results from the user study regarding
the detection of the implausibility of the space are de-
Perception of a Spatial Implausibility Caused by Seamless Covert Teleportation
Figure 4: Procedure of the user study testing detection thresholds for a novel type of impossible spaces. Green boxes indicate
questionnaires for participants, and red boxes denote drawing tasks.
(a) Non-closed corridor. (b) Multiple start positions.
(c) No detection.
Figure 5: Drawings (a) and (b) count as detection of the
teleportation, while (c) counts as no detection.
picted in Figure 6. This chart shows the detection
rates for each condition (C0, C1, C2, H0, H1, and
H2). The blue columns depict which percentage of
the participants detected the space implausibility, and
the red columns represent the percentage that did not
notice this. The main assumption is that if the user
doesn’t perceive the implausible space, they believe
that they reached the same physical space location af-
ter each navigation task in the corridor.
Hypothesis 1 investigated whether the implausi-
ble space detection increases if larger sections of the
corridors are skipped. In the comparison of detection
rates, a pattern was noted: in conditions C1 and H1,
participants detected the implausible space 3 and 1
times, respectively. In contrast, for conditions C2 and
H2, these numbers increased to 7 and 4 detections,
respectively. However, the application of McNemar’s
test did not yield statistically significant evidence (p
Figure 6: Column chart representing the detection of the
space manipulation for each condition. “Yes” represents the
corridor drawings where an implausible space was detected
and “No” represents the drawings it was not detected. For
each corridor condition, n=25 drawings were analyzed.
= 0.25 and 0.125, respectively) to justify the rejection
of the null hypothesis which indicates no difference
in detection of implausibility in terms of the degree
of skip. Thus the hypothesis that increasing the level
of implausibility would make the user more prone to
notice the seamless teleportation effect cannot be ac-
Hypothesis 2 investigated whether corridor lay-
outs influence a user’s ability to detect seamless tele-
portation and alters their cognitive map of the space.
To examine this, we employed McNemar’s test for
repeated measures to assess differences in detection
between the conditions C0,H0; H1,C1; and C2,H2.
However, the analysis faced a limitation due to the
low number of participants who successfully detected
teleportation or a distortion in the spatial layout. Con-
sequently, the p-values obtained (0.375, 0.25, 0.625)
for all three comparisons were significantly high.
This outcome negates the necessity for applying a
Bonferroni correction, as the p-values inherently in-
dicate a lack of statistical significance in the differ-
ence between the corridor layouts. This finding does
not align with the previously presented research, af-
firming the potential influence of corner landmarks in
HUCAPP 2024 - 8th International Conference on Human Computer Interaction Theory and Applications
aiding user’s navigation and layout identification.
Participants faced challenges in discerning the
condition without a skip. This is evidenced by 7 out
of the 25 participants identifying an implausible space
in the C0 condition and four in the H0 condition, in
contrast to 3 and 1 participant in the C1 and H1 con-
ditions, respectively. This initial observation under-
scores the success of the seamless teleportation effect.
This finding was not expected before the realisation of
the study. Out of the 11 implausible space detections
in the zero conditions, 9 of them (82%) started with
either a one-section skip (C1 or H1) or a two-section
skip (C2 or H2). This leads us to believe that those
participants might have taken the first corridor as a
reference and compared the other two corridors to it.
5.2 Change in Size and Shape Detection
Since 21 (84%) participants out of 25 did not notice
the spatial manipulation by itself but instead noticed
a change in SoS, we also examined this for all pat-
terns. For both, the hexagon- and the circular-shaped
corridors, 17 participants detected a change in the size
or shape of the environment while 8 did not. This was
expected since they could compare the trials with each
other. However, this supports the previous finding that
corners did not help in better perceiving the telepor-
tation. However, it should be noted here that such a
detection in the hexagonal shape means the user per-
ceives less turns or corners thus changing the layout
he draw from a hexagonal to a square or pentagon de-
spite the fact that all the angles at the corner are still
equal to 120
. While for the circular corridors, the
change in size refers to perceiving the same layout
a full circle which is smaller thus the cognitive map
would be the same.
To check for the sequence effect on the detection,
we combined the skips into two categories like C0 to
C1 as “1 Section Different” and larger changes like
from C0 to C2 as “2 Sections Different”. There was
a total of 61 “1 Section Different” corridor changes
and 39 “2 Sections Different” corridor changes. This
difference can be explained by the higher chance of
having “1 Section Different” corridor changes since
there are simply more possible combinations. There
is only a small difference in the detection ratios be-
tween “1 Section Different” (49% detected) and “2
Sections Different” (54% detected).
The primary implication of this study is that the
proposed scene manipulation does not cause sickness
or discomfort in users, unlike other similar methods
such as redirected walking. Since users had diffi-
culties identifying when the manipulation occurred,
this highlights the effectiveness of the implementa-
tion, suggesting that such scene manipulations are un-
likely to cause discomfort. Another key finding is the
potential to preserve the overall cognitive map layout
of the environment, despite distortions caused by tele-
portation. This was particularly evident as most users
still perceived a circle, even though parts of it were
skipped. In contrast, in the hexagon experiments,
the change was perceived as fewer turns, altering the
hexagon into a pentagon or square, implying a change
in shape. Therefore, these insights enable us to deter-
mine where this method should be applied, based on
the need to maintain an accurate cognitive map.
Our user study includes two separate rounds of walk-
ing, where after each round the participant had to
perform the drawing task. Because of this sequen-
tial approach, the participants might have experienced
a learning effect since in the second walking round
most anticipated that there will be another drawing
task. Due to the limited number of participants, this
could not be avoided. From of the 75 corridor draw-
ings in each round, we see that in the first round
of the walking series 12 drawings were attributed to
a correct spatial manipulation detection (16%). In
the second round, it was 21 drawings (28%). This
is an increase of 12% in the second round. By do-
ing the McNemar’s exact test, we get a one-tailed p-
value of p=0.057 which is very close to being a sig-
nificant difference and might indicate a correlation.
This supports that future studies using the drawing
method should focus on having one condition per user
to avoid the learning effect. Another limitations of the
drawing task is that users stated in the informal feed-
back that participants had to remember three corridor
paths at once. During our study, some participants re-
ported not being sure in which sequence the corridor
conditions appeared. By decreasing the number of
corridors a participant has to walk this problem could
probably be mitigated.
In this work, we created a new architectural layout
which implemented spatial manipulation using por-
tals and teleportation. Our architectural layout con-
sisted of closed-loop circular and hexagonal corri-
dors, in which users skipped up to 33% of the path
through teleportation. To collect the necessary data,
we developed a user study where the main task was
for the participants to walk through corridors with dif-
Perception of a Spatial Implausibility Caused by Seamless Covert Teleportation
ferent levels of space manipulation and then draw the
floor plan of these virtual corridors. Overall, the de-
tection of the correct spatial manipulation was rela-
tively low, between 4% and 28% depending on the
corridor condition. Participants could also not signif-
icantly tell apart the three levels of space manipula-
tion. This means that our implementation of spatial
manipulation shows a valid approach to manipulating
the space without the users knowing what exact ma-
nipulation was done. We also did not find any ev-
idence proving that there is a significant difference
in detection for hexagonal corridors compared to cir-
cular ones. Because we noticed that the participants
perceived the corridors to be of different SoS, we ad-
ditionally analyzed this aspect. We categorized any
detection of change in SoS separately from the detec-
tion of the implausible space. A total of 21 (84%)
out of 25 participants did notice an SoS change going
from corridor to corridor. This is an indicator that the
spatial manipulation was felt to a certain degree, but
the participants did not correctly specify which kind
of manipulation.
7.1 Future Work
Future studies will include a larger number of par-
ticipants and assign each a single drawing task to
mitigate learning effects. Furthermore, investigat-
ing a variety of polygon shapes could provide in-
sights into how different angles influence the percep-
tion of impossible spaces. Practical applications of
these impossible spaces also require further explo-
ration. Lastly, efforts can be made to quantify detec-
tion in more intricate corridor designs, such as those
with left and right turns, prior to teleporting the user.
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