=Paper= {{Paper |id=Vol-3090/paper42 |storemode=property |title=Measurement of Presence by a Presence Counter Based on Breaks in Presence |pdfUrl=https://ceur-ws.org/Vol-3090/paper42.pdf |volume=Vol-3090 |authors=Natalya Averbukh,Boris Velichkovskiy |dblpUrl=https://dblp.org/rec/conf/ims2/AverbukhV21 }} ==Measurement of Presence by a Presence Counter Based on Breaks in Presence== https://ceur-ws.org/Vol-3090/paper42.pdf
Measurement of Presence by a Presence Counter
Based on Breaks in Presence
Natalya V. Averbukh1 , Boris B. Velichkovsky2,3
1
  Ural Federal University, 19 Mira street, Ekaterinburg, 620002, Russian Federation
2
  Faculty of Psychology, Moscow State University, Mokhovaya bld. 11/5, Moscow, 125009 Russian Federation
3
  Moscow State Linguistic University, Ostozhenka 38 bld. 1, Moscow, 119034, Russian Federation


                                         Abstract
                                         The paper is concerned with methods of measuring presence. The physiological and behaviour methods
                                         are situation-specific whereas subjective method is used after virtual session. In this paper we focus on
                                         the method that evaluates the presence counter based on breaks in presence (BiP). The advantage of this
                                         method is its implementation during the virtual session, during the virtual experience.
                                             Within the experiment, 22 participants walked around the virtual Asian park and searched for virtual
                                         vases. They gave signals when BiPs occurred. The presence counter can be calculated based on this
                                         data. To validate this approach the participant were asked to answer ITC-Sense of Presence Inventory
                                         (ITC-SOPI) after the virtual session.
                                             Our approach of computing the presence counter involves the Markov chain that is a simplest model
                                         of stochastic process.
                                             Presence counter based on BiP and the Markov chain was proposed by Slater and Steed. They
                                         consider the discrete time model. In the paper we revisit this approach and, additionally, develop the
                                         continuous time Markov chain based method of presence counter. The calculation of the correlation
                                         between the presence counters based on BiP and results of ITC-SOPI showes that the counters relied
                                         on the continuous time Markov chain are most sensitive. This paper shows that a BIP-based presence
                                         counter can be used as an effective presence measure.

                                         Keywords
                                         Virtual reality, presence, mediated presence, presence measurement, breaks in presence, Markov chains,
                                         presence counter




1. Introduction
The virtual reality is a special technology that makes it possible to create an interactive three-
dimensional environment. The presence is the main phenomenon in the study of virtual reality.
”...The phenomenon of Presence is that an individual experiences the illusion of being present
in the same reality with objects or subjects that are not in the directly observable reality of
the individual. It is necessary to make a reservation at once that in this context we are not
talking about the situation of full consciousness of the individual that the reality he feels is in
fact artificially created or caused to exist in another way” [1, p.38].


IMS 2021 - International Conference ”Internet and Modern Society”, June 24-26, 2021, St. Petersburg, Russia
Envelope-Open natalya_averbukh@mail.ru (N. V. Averbukh); velitchk@mail.ru (B. B. Velichkovsky)
Orcid 0000-0002-8232-6711 (N. V. Averbukh); 0000-0001-7823-0605 (B. B. Velichkovsky)
                                       © 2021 Copyright for this paper by its authors. Use permitted under Creative Commons License Attribution 4.0 International (CC BY 4.0).
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                                       CEUR Workshop Proceedings (CEUR-WS.org)
424                                                                               PART 2: Internet Psychology




         The authors of [2] call the experience of presence in the virtual world mediated presence. In
      their opinion, the mediated presence is a sense of presence in the external world, in the realization
      of which technology plays an important role. When a person experiences a strong mediated
      presence, his/her experience shows that the technology has become a part of themselves, and
      the mediated reality has become a part of the Other. In the context of this work, the presence
      will be understood as an mediated presence.
         The presence as a phenomenon can be recorded and measured. The question of selecting
      measurement methods is extremely important. The subjective methods, primarily questionnaires
      and inventoies, can be used. The behavioral and physiological measurement methods can also be
      used. Note that the subjective methods depend on the subjective opinion of the subjects and they
      do not measure presence at the moment of experience. On other hand, they are universal. The
      behavioral and physiological methods depend on events that trigger behavioral and physiological
      responses. Slater proposed a method based on breaks in presence (BiP) [3]. Most participants
      in virtual environments do not experience being present all the time while interacting with VR.
      They can hear sounds from the real world and feel the touch of objects from the real world.
      These sensations can cause the consciousness moves from the virtual environment to the real
      one. However, if a person reports a transition from the virtual environment to the real one, it
      means that they have just felt themselves in the virtual environment. In this way, messages
      about breaks in presence help to measure the presence. This method allows us to know that a
      participant experiences the presence at the moment when he experiences it. Slater measured
      the presence based on the CAVE technique and the movement around the chess table with 3D
      chess. The movement was carried out by walking. Slater used a mathematical model of discrete
      time Markov chains.
         The main question of this study is whether it is possible to measure the presence by the
      BiP method using Markov chains in the HMD technology and moving by walking for small
      distances and teleporting for significant distances? Will the BiP-based presence counter measure
      the experience that is usually regarded to as presence? What methodological features should
      be taken into account? To address these question we extend Slater’s approach to continuous
      time Marcov chain. Moreover the validity of the BiP-based presence counter was evaluated by
      correlation with the ITC-Sense of Presence Inventory (ITC-SOPI) [4].
         Notice that in this paper, we did not set out to link the presence with any individual charac-
      teristics of the participants, we were only focused on the validity of the presence counter.


      2. Background
      A large number of publications have been devoted to the presence, since the 90s. From relatively
      old reviews, for the purposes of this paper, it is interesting [5].
         Now, a number of reviews of more recent works related to the concept of presence have been
      published. The paper [6] provides a theoretical overview, and the paper [7] discusses methods
      for measuring presence, and suggests, according to the authors, unused methods. The paper
      [8] discusses about immersion, social presence and co-presence as the ability to be somewhere
      together, to perceive and be perceived by other people, to interact with people. The paper [8]
      also raises the question of realism and veracity.
IMS-2021. International Conference “Internet and Modern Society”                                              425




       Close to this is the discussion of perceptual and social realism as important aspects of the
    presence [9]. Perceptual realism occurs when the environment supports the action in it, when
    the response of the environment is perceived as plausible and adequate. Social realism refers to
    a more general concept: when an event that occurred in the environment is plausible, when it
    can happen in the real world. There can be high perceptual and low social realism in a virtual
    environment.
       These concepts echo Slater’s earlier ideas of place illusion and plausibility [10].
       The paper [11] mentions three main approaches to the study of the presence: the mediated-
    objective school of thought approach, mediated-subjective school of thought approach and
    inner presence school of thought approach. The first two schools describe the presence as an
    essential element in mediated experience. The third describes the presence as a phenomenon
    that does not require median systems (virtual reality technologies, etc.).
       The schools of the mediated presence define presence as the perceptual illusion of immediacy.
    [11] criticizes this approach, although pointes out that schools of mediated presence provide
    good definitions of a number of concepts, such as immersion and involvement. According to
    [11], the mediated presence approach does not answer important questions: why do we feel the
    presence, what is its role? Trrberti and Riva, the researchers of inner presence school raise the
    similar questions [12]. They also talk about the schools of mediated presence, which, according
    to them, do not answer questions about the evolutionary cause of the presence, about its causes
    and purpose.
       Representatives of the third school in their works define the phenomenon of presence as a
    conscious sense of being in the external world, as a phenomenon that controls the division into
    the inner and the outer [13], [14], [15], [16], [17], [18], [19], [20], [12]. They suggest treating the
    presence as a presence in any environment, not necessarily created by virtual reality technology.
    They see the presence as a central part of conscious mental life [20]. The sense of presence,
    according to these researchers [12], allows you to constantly adapt your own activities to the
    external environment. This approach is also related to the concepts of intentions and actions:
    the more the environment allows you to implement intentions, turn them into actions, the
    stronger the experience of presence.
       There are other works in which presence is considered more broadly than presence in a virtual
    environment. For example, [21] assumes that the presence is associated with the successful
    implementation of intentions, so that a person feels like a successful author of their own actions.
    In [? ], the presence is considered as a personal state that occurs in both real and virtual
    environments, and mediation is not only a technique for creating virtual reality, but in general,
    any situation where actions are implemented indirectly, so presence is analyzed by the example
    of driving a car to demonstrate the flexibility of this approach.
       Another interesting work [22] is devoted to the relationship between the presence and
    the perception of own movement in a virtual environment. In contrast to the researchers
    of the school of inner presence, who suggest that the virtual environment creates limitless
    possibilitiesunlimited opportunities [22] indicate that virtual environments, on the contrary,
    are limited in comparison with reality, in particular, it is very difficult to move. In [22] the
    presence and illusory self-movement in a virtual environment are linked. The experimental
    material shows that the presence is related to how one’s own motion is perceived in a virtual
    environment.
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         We should also mention the works [23], [24], [25], devoted to the relationship of metacognitive
      processes and the presence. Metacognitive processes, such as monitoring and error correction,
      prevent cybersickness, but can also prevent the appearance of the presence, since these cognitive
      processes lead to the fact that a person pays attention to the low naturalness of virtual scenarios
      [24]. Purposeful study of different classes of psychological factors of the sense of presence will
      lead not only to progress in the construction of a general psychological theory of the sense of
      presence, but also will allow us to find effective solutions to fundamental and applied problems
      using virtual reality technologies [24].
         The presence, regardless of the definition of which school the researcher uses, is a subjective
      experience in which a person interacts in one way or another with the reality surrounding him
      (for representatives of schools of mediated presence – virtual).
         The presence measure is necessary in order to establish whether presence actually increases
      interaction with the virtual environment system, and to better understand the factors that
      may drive this phenomenon [26]. The question of a valid measure of presence was pointed in
      [26]. The measuring of the presence in the framework of the subjective, the behavioral and the
      physiological methods was consider since [27], [28].
         The subjective method uses questions such as ”how real did the virtual environment seem to
      you?”, ”was the virtual environment really the place you were in – or just a series of images
      shown to you?”, [27], [28], [26], [29].
         The behavioural method tracks the user’s behaviour, for example, whether the user Shield
      himself/herself when an object is thrown at his head, [27], [28], [26], [29].
         The physiological methods record changes in the heart rate, skin temperature, GSR, respira-
      tory rate, etc. The experimenter looks at whether a person is stress in a stress situation in the
      virtual environment [27], [28], [26], [29].
         In 2000 Slater, together with his colleagues, proposed approach to measuring presence [3].
      According to Slater, traditional methods of measuring presence have certain disadvantages. In
      particular, the responses to the questionnaire can ensure that only conscious and voluntary
      responses are integrated over time. Behavioural measures, such as responding to the sudden
      appearance of an object, require events in the environment. The physiological measurements
      offer, according to Slater, a promising way forward. However, the physiological methods
      are used in cases where the environment causes anxiety (for example, go to a pit). That is
      why they are only suitable for a very small number of applications. What the physiological
      response is appropriate for observing a virtual chair, a room, or a deck of a ship? Relying on
      the physiological responses to specific events or objects in a virtual environment does not offer
      a general solution [30].
         The main idea of the approach proposed by Slater and his co-authors can be described as
      follows. A person who is in the virtual reality environment switches between being present in
      the virtual environment and being present in the real environment [30].
         Initially, Slater and Steed intended to use the mathematical model of Markov chains to
      calculate presence based on BiP. Later [31], the Slater team rejected this method as too complex.
      Natural noises was the cause of BiP in operation [3]. The noises was modeled by experimenters
      in later works [31].
         Let as briefly describe the approach of [3] that provides main idea of method used in this
      paper. In the immersive virtual environment, the participant receives a continuous stream of
IMS-2021. International Conference “Internet and Modern Society”                                           427




    sensory data. This data is mostly visual, coming from a virtual environment. But also often
    this data is auditory from the real world or real haptic and kinesthetic data (for example, the
    weight of the HMD). Sometimes, the sensor data of the virtual environment shows disturbances.
    Or a close-up of an object shows its texture mapping. Additionally data from the real world
    can intrude: the phone rings, there is a sudden movement of air when the door opens, the
    temperature changes, the cable is wrapped around the leg. Sometimes, the participants’ internal
    mental processes make them realize that they are actually in the virtual environment when the
    participant in the laboratory or exhibition hall, and not in the illusory place presented to them
    by the virtual environment [3].
       In other words, two alternative gestalts are available to each person at any time. The first
    gestalt is ”I am in the place depicted by the VE system” Bellow, we following [3] denote it by
    “V”. The second gestalt is ”I’m in the lab in the computer science building, wearing a HMD”.
    This state is denoted by “R”. At every moment, the individual can occupy only one state. Being
    in the virtual presence in the virtual environment can be considered as the degree of preference
    of the state V [3].
       However, during the experience of being in the virtual environment, as expected, the individ-
    ual usually experiences transitions between state V and state R. These time instants when the
    individual switches from one interpretation to another, in particular, from V to R, are studied. It
    is not possible to ask participants to report transitions from R to V because this will require them
    to immediately exit the presence state. However, according to the authors [3] the experimenter
    can ask participants to report transitions from V to R. Since the transition from V to R implies
    the feeling of the presence, we can use this information to evaluate the being of presence.
       On the other hand, the information of transition from R to V is unavailable. Thus, Slater
    proposed to consider two cases: low and high presence. The low presence case implies that the
    state “R” is basic, when the high presence case means that primary individual occupies the state
    “V”.
       In their work, Slater and Steed provide the mathematical calculations that allow using the
    technique of Markov chains to derive the formula for counting the experienced presence
    depending on the reported BiPs. As a consequence of this formula, the probability that the
    participant experienced the presence is computed. The value of this probability serves as a
    presence counter. This formula is modified for conditions involving high presence and for
    conditions involving low presence [3].
       Slater and Steed used the discrete time Marcov chain assuming the time unit equal to 10
    seconds. Participants reported BiP orally.
       In this framework, the low presence condition means that the transition from R to V occurs
    just before BiP. Whilst, the high presence is modeled by immidiate recovering of V after BiP.
       To distinguish the low and high presence cases Slater and Steed used discriminator question.


    3. Methods
    3.1. Participants
    The study involved 22 people, including 11 women and 11 men. With the exception of two
    people (men and women), all participants had or pursued the university degree.
428                                                                            PART 2: Internet Psychology




      Figure 1: General view of a virtual scene.


      3.2. Equipment: hardware and software
      The environment uses the vr HTC Vive headset. It connects with the computer via cables. Apart
      from a VR headset, the Vive system is equipped with special hand-operated controllers and with
      two infrared cameras for tracking a person in the environment. In order to implement both
      systems, the Unity 3D development environment was used, along with the C# programming
      language, a SteamVR plugin etc.
         The most elaborated and suitable for the experiment set of visual resources was chosen
      at the design stage in order to create the effect of presence and immersion into the virtual
      environment.
         Visually, the scene is a reconstruction of a classical Far-Eastern mountain monastery (see
      Figure 1).

      3.3. Procedure
      The participants were asked to provide their name, offered to wear HMD, and, having seen
      the virtual environment with them, follow the opened area, which is an Asian-style park. The
      movement was carried out by means of physical movement in a limited space and by means of
      successive teleportations over long distances. In the park, the participants had to fix specially
      selected objects along the way – low rounded vases (see Figure 2). The objects were chosen
      according to the principle of average notability and, at the same time, naturalness for any
      location of the created scene. The task was to give meaning to the walk in the park, make it
      purposeful and encourage the participants to move around the space of the park.
         The stay in the environment was limited by 7 minutes. After the first five minutes, the
      participants could leave the environment at any time they wanted. The participants were
      instructed to say the word ”here” loudly every time they felt BiP. During the experiment, an
IMS-2021. International Conference “Internet and Modern Society”                                         429




    Figure 2: Detecting a vase and indicating it with a laser pointer .


    audio recording was conducted. The time at which the subjects uttered the word ”here” was
    recorded on an audio recording.
       During the experiment, the number of vases found was also recorded. The participant could
    see them on the counter on his hand (see Figure 2). A large or small number of vases found
    were not rewarded or punished in any way.
       As in the original paper by Slater and Steed the discriminator question about the experience
    of the presence was asked after the experiment. The participants were asked where they felt
    during the session. Also, the reasons for pronouncing the signal ”here” were specified. If the
    participant never said ”here!”, then the question ”why?” was asked. Did the participant always
    feel like they were here, in a real room? Did the participant feel like they were in an Asian park
    all the time?
       The Russian version of the ITC-Sense of Presence Inventory (ITC-SOPI) was offered after the
    experiment. It is described in the paper [4]. This inventory is based on four factors:

        • Sense of Physical Space;
        • Engagement;
        • Ecological Validity;
        • Negative Effects.

       These four factors cannot be combined into a single measure of presence. According to [4],
    the main determinants of the Sense of Physical Space factor are the variables of the media
    form, i.g., the properties of the virtual environment. The questions on this scale relate to
    the participants’ experiences about the reality of what is happening, the ability to touch the
    elements of the environment, to interact with them, ect. The second factor that is considered is
    Engagement. One of the points of this factor directly examines how attractive respondents find
430                                                                                PART 2: Internet Psychology




      the content. Other questions that make up this scale relate to excitement and emotionality. The
      answers depend on the media content, but are also amplified by the media form.
         The questions that include the third factor, Ecological Validity, concern the plausibility and
      realism of the content, as well as the naturalness of the environment. The amount, degree, and
      sequence of sensory stimulation, according to the authors, improves perceived naturalness and,
      in turn, increases scores on this scale. The high immersiveness of the media form (i.e., how it
      allows the participants to experience immersion), gives an increase of Ecological Validity. The
      higher imeressiveness is the less the impact of the content on the perception of authenticity is.
      The difference in photorealism also leads to differences in the scale of Ecological Validity.
         The questions related to the fourth factor, negative effects, are less related to the first three
      factors than to each other. In [4] Negative Effects were not strongly correlated (positively or
      negatively) with Engagement or Ecological Validity. However, they had a low but significant
      positive correlation with the Sense of Physical Space. Some negative effects, such as headache,
      eye strain, fatigue may be associated with the media form. Further, content can affect on the
      Negative effects: if it is perceived as boring, the participants may give appropriate ratings of
      fatigue or even headache [4].

      3.4. Presence counter based on BiP
      The presence counter was calculated based on the probability formula of experiencing presence,
      which was derived using Markov chains. The formulas given in [3] were applied. Time was
      discrete in the work [3]. The length of the time interval was 10 seconds. Also, the presence
      counter at the interval length of 5 seconds was calculated to increase the sensitivity of the
      method. In addition, formulas for continuous time were derived.
         As in paper [3] we study the stationary distribution. Notice that [32] the stationary distri-
      bution exists and moreover the Markov chain converges to it exponentially. The approach
      proposed in (Slater, Steed, 2000) implies that we are to solve the inverse problem: we compute
      the stationary distribution using the information on breaks in presence, and then we are to
      find the matrix of transition probabilities that provides the measure of presence. Following
      [3] we consider two cases. First is the low presence case. Roughly speaking, it means that the
      participant leaves the state of presence once he/she reaches it. The second case we examine is
      the high presence situation. It implies that the state no-presence is leaved once the participant
      reaches it.
         𝑝𝐿 (𝑏) is the probability of presence, corresponding to the stationary distribution, for conditions
      of low presence at discrete time [3]:

                                                            𝑏−𝑘
                                                 𝑝𝐿 (𝑏) =
                                                            𝑛−1
        where
        𝑏 is the number of BiPs,
        𝑛 is the number of time intervals.
        𝑘 is the number of ”close BiPs”, that is, BiPs in adjacent time intervals.
        𝑝𝐻 (𝑏) is the probability of presence for high presence conditions at discrete time [3]:
IMS-2021. International Conference “Internet and Modern Society”                                         431




                                                       𝑛−1−𝑏
                                            𝑝𝐻 (𝑏) =
                                                        𝑛−1
      where
      𝑏 is the number of BiPs,
      𝑛 is the number of time intervals.
       Furthermore, we extend the approach of [3] assuming the continuous time. In this case, the
    dynamics of probabilities is determined by so called Kolmogorov equation that is an ordinary
    differential equation [32]. As above, we consider the inverse problem. We compute the matrix
    of transition rates by using the stationary distribution computed by BiPs. We also follow [3]
    and examine two cases: low presence and high-presence. However, the continuous time setting,
    implies that we are to introduce the relaxation time that is an external parameter. For the low
    presence case, it is assumed that the participant occupies the presence state once it is reached
    for the averaged time interval of the length 𝜇 −1 . The case of high presence is opposite. Here
    we assume that the participant will reach the presence state once he/she leaves it for the time
    interval of the averaged length equal to 𝜇 −1 . To adjust the continuous and discrete time models,
    one is to let 𝜇 −1 equal to the time unit for the original discrete time model proposed in [3].
      𝑝𝐿 𝑉 is the probability of presence for low-presence conditions at continuous time:

                                                          𝑏
                                              𝑝𝐿 𝑉 =
                                                        𝑇 ∗𝜇
      where
      𝑏 is the the number of BiPs,
      𝑇 is the total time of the virtual reality session,
      𝜇 = 0.1 with a relaxation time taken equal to 10 seconds.
      𝜇 = 0.05 with a relaxation time taken equal to 5 seconds.
      𝑝𝐻 𝑉 is the probability of presence for conditions of high presence at continuous time:
                                                          𝜇
                                             𝑝𝐻 𝑉 =
                                                       𝜇 + 𝑏−𝑘
                                                            𝑇
      where
      𝑏 is the the number of BiPs,
      𝑇 is the total time of the virtual reality session,
      𝜇 = 0.1 with a relaxation time taken equal to 10 seconds.
      𝜇 = 0.05 with a relaxation time taken equal to 5 seconds.


    3.5. Mathematical and statistical methods
    In this paper, the mathematical model of Markov chains is used.
       In this paper, we use the Pearson correlation coefficient for

        • calculation of the relationship between the scales of the ITC-SOPI questionnaire based
          on the responses of the subjects to the Russian version of the ITC-SOPI;
432                                                                              PART 2: Internet Psychology




          • calculation of the relationship between the ITC-SOPI scales and different variants of
            calculating the probability of presence based on BiP;
          • calculation of the relationship between the presence measures and the effectiveness of
            the search for vases, which is expressed in the number of vases found.


      4. Results and discussions
      The results of the ITC-SOPI questionnaire were calculated for all participants of the experiment.
      A BiP-based presence counter was calculated for each participant. The probability of presence is
      calculated when calculating the presence counter. If the participant gave a definite answer that
      he/she felt a presence most the time, then the formula for high presence condition was applied.
      If the participant gave a definite answer that he/she felt no presence or felt little presence, then
      the formula for low presence condition was applied. If the participant did not give a definite
      answer, then both formulas were applied.
         Presence counter was calculated for the group of participants in the experiment 8 times
      according to the following principles:
         The presence counter was calculated under the following frameworkes

          • Time interval/relaxation time is equal 5 sec or 10 sec;
          • Discrete or continuous time Markov chain is used;
          • The high or low presence assumption was applied to the undecided participants

        And always the high presence assumption was applied to the participants reported a high
      presence. Always the low presence assumption was applied to the participants reported low
      presence or no presence.
        This gives the 8 ways of calculation of presence counter
        It is nessecery to compare the presence counter with the results of the ITC-SOPI to determine
      the validity of the presence counter.
        The ITC-SOPI results were also calculated. The Pearson’s correlation analysis was performed
      between the scales of the questionnaire. See Table 1.


       Table 1: Correlations between the ITC-SOPI scales, 𝑟𝑐𝑟𝑖𝑡 = 0.42 (𝑝 ≤ 0.05) for the first level of
                significance, 𝑟𝑐𝑟𝑖𝑡 = 0.54 (𝑝 ≤ 0.01) for the second level of significance
                       Sense of Physical Space Engagement Ecological Validity Negative Effects
       Sense of                     –                      –                  –               –
       Physical
       Space
       Engage-                     0.70                    –                  –               –
       ment
       Ecological                  0.77                  0.61                 –               –
       Validity
       Negative                   -0.02                 -0.04               0.13              –
       Effects
IMS-2021. International Conference “Internet and Modern Society”                                              433




      Table 1 shows that the first three factors of ITC-SOPI significantly correlate with each other
    for the second level of significance. This corresponds to the results described in [4].
      The Pearson’s correlation analysis was conducted between the results of the inventory and
    the probabilities of experiencing presence, see Table 2.


    Table 2: Correlations between the results of the questionnaire and the probability of presence
            based BiP, 𝑟𝑐𝑟𝑖𝑡 = 0.42 (𝑝 ≤ 0.05) for the first level of significance, 𝑟𝑐𝑟𝑖𝑡 = 0.54 (𝑝 ≤ 0.01)
            for the second level of significance
      Probabilities of Sense of Physi- Engagement                  Ecological Va- Negative
      presence             cal Space                               lidity               Effects
                     The length of the time interval/relaxation time is 10 seconds
      𝑝𝐿 (𝑏) for uncer- 0.509                 0.318                0.511                0.063
      tain and low
      presence;
      𝑝𝐻 (𝑏) for high
      presence
      𝑝𝐻 (𝑏) for uncer- 0.487                 0.392                0.482                0.333
      tain and high
      presence;
      𝑝𝐿 (𝑏) for low
      presence
      𝑝𝐿 𝑉 for uncer- 0.554                   0.336                0.541                0.043
      tain and low
      presence;
      𝑝𝐻 𝑉 for high
      presence
      𝑝𝐻 𝑉 for uncer- 0.551                   0.416                0.520                0.241
      tain and high
      presence;
      𝑝𝐿 𝑉 for low
      presence
                      The length of the time interval/relaxation time is 5 seconds
      𝑝𝐿 (𝑏) for uncer- 0.577                 0.350                0.541                -0.015
      tain and low
      presence;
      𝑝𝐻 (𝑏) for high
      presence
      𝑝𝐻 (𝑏) for uncer- 0.349                 0.348                0.403                0.355
      tain and high
      presence;
      𝑝𝐿 (𝑏) for low
      presence
434                                                                             PART 2: Internet Psychology




        𝑝𝐿 𝑉 for uncer- 0.657                  0.378              0.592              -0.051
        tain and low
        presence;
        𝑝𝐻 𝑉 for high
        presence
        𝑝𝐻 𝑉 for uncer- 0.538                  0.428              0.523              0.355
        tain and high
        presence;
        𝑝𝐿 𝑉 for low
        presence

         Table 2 shows that the probabilities of presence significantly and positively correlates with
      the two scales of the questionnaire. These scales are Spatial Presence and Ecological Validity.
      The highest correlation values, significant for the second level of significance, were obtained
      when comparing the first and third ITC-SOPI scales with the probabilities of presence, calculated
      using a formula designed for low presence condition for the participants who did not give a
      clear answer or gave an answer about low presence, and using a high presence formula for
      the participants who gave a certain answer about high presence, for continuous time with a
      relaxation time taken equal to 5 seconds. This shows that this formula allows to create the most
      sensitive presence counter. However, when calculating the probabilities of presence using a
      formula designed for high presence conditions for the participants who did not give a clear
      answer and for the participants who reported high presence, and using a low presence formula
      for the participants who reported low presence or did not experience it, for continuous time
      with a relaxation time taken equal to 5 seconds, a correlation of the probability of presence with
      the Engagement scale was obtained.
         Since, see Table 1, the first three ITC-SOPI scales correlate with each other, this result seems
      to be natural.
         The relationship between the presence counter, which represents the probability of presence,
      and the ”Sense of Physical Space” scale seems obvious. The presence counter is based on BiP and
      the participants were instructed to report BiP every time they felt like they were in a real room,
      not in an Asian park. Therefore, it is obvious that the presence counter should correlate with
      the scale associated with the participants’ experiences about the reality of what is happening,
      the ability to touch the elements of the environment, to interact with them.
         The focus on the environment, as measured by the second scale, ”Engagement”, can also affect
      whether a participant feels like they are in a virtual environment or in a real room. However,
      this issue needs further clarification.
         Apparently, the naturalness and plausibility of the environment, as measured by the ”Ecolog-
      ical Validity” scale, also influenced how the participant felt in the virtual environment.
         It should be understood that the application of the formula of high presence conditions for
      undecided participants does not in itself give more valid results. The greater validity of the
      results, in which the probability of presence in undecided participants is calculated using the
      low-presence condition formula, is due to the fact that this formula seems to reflect the presence
      they experienced more than the high-presence condition formula. The correlation between the
IMS-2021. International Conference “Internet and Modern Society”                                                 435




    two indicators suggests that one will change in the same way as the second. In our case, the
    probability of presence calculated using BiP is expected to increase or decrease in the same
    way as the ITC-SOPI scales. The method of calculating the probability of presence has this
    property to the greatest extent, when the formula of high presence conditions is used for those
    participants who indicated a high presence, and the formula of low presence conditions is used
    for those who indicated a low presence or no presence and for those who were undecided. But
    of course we get the significative correlation between ITC-SOPI scale “Engagement” and the
    presence counter using the formula of high presence conditions for those participants who
    indicated a high presence and for those who were undecided, and the formula of low presence
    conditions for those who indicated a low presence or no presence.
       To clarify the optimal formula, additional studies will be required on an extended sample
    group and with a more strict discriminant question.
       The number of vases found by the participants was also calculated, but it was not related to
    either the results of the presence counter or the results of the ITC-SOPI, see Table 3.


    Table 3: Results of calculating the correlation between the number of vases found and marked
             by the subject during the experiment and the presence indicators, 𝑟𝑐𝑟𝑖𝑡 = 0.42 (𝑝 ≤ 0.05)
             for the first level of significance, 𝑟𝑐𝑟𝑖𝑡 = 0.54 (𝑝 ≤ 0.01) for the second level of significance
     Presence indicators                                     Correlation between the number of found
                                                             vases and the presence indicator
                       The length of the time interval/relaxation time is 10 seconds
     𝑝𝐿 (𝑏) for uncertain and low presence;                  0.143
     𝑝𝐻 (𝑏) for high presence
     𝑝𝐻 (𝑏) for uncertain and high presence;                 -0.271
     𝑝𝐿 (𝑏) for low presence
     𝑝𝐿 𝑉 for uncertain and low presence;                    0.163
     𝑝𝐻 𝑉 for high presence
     𝑝𝐻 𝑉 for uncertain and high presence;                   -0.248
     𝑝𝐿 𝑉 for low presence
                        The length of the time interval/relaxation time is 5 seconds
     𝑝𝐿 (𝑏) for uncertain and low presence;                  0.124
     𝑝𝐻 (𝑏) for high presence
     𝑝𝐻 (𝑏) for uncertain and high presence;                 -0.285
     𝑝𝐿 (𝑏) for low presence
     𝑝𝐿 𝑉 for uncertain and low presence;                    0.168
     𝑝𝐻 𝑉 for high presence
     𝑝𝐻 𝑉 for uncertain and high presence;                   -0.245
     𝑝𝐿 𝑉 for low presence
                                              Results of ITC-SOPI
     Sense of Physical Space                                 0.242
     Engagement                                              0.002
     Ecological Validity                                     0.164
436                                                                             PART 2: Internet Psychology




       Negative Effects                                  -0.214

        The effectiveness of vases search is not related to the presence, as shown in table 3. It can be
      assumed that the presence does not affect the performance task related with the objects search
      and the objects search does not affect the presence.


      5. Conclusion
      In this study, we considered the measuring presence of the using primarily information available
      during the session of interacting with the virtual reality that does not require an emotionally
      rich content of the environment. Such a measure is a presence counter based on the calculation
      of the probability of presence using the Markov chain model. During the session, the participant
      reports the BiP, while continuing to perform the task. In this experiment, we used an environ-
      ment that was an Asian park, where the participants could move around using teleportation
      and find vases. The experiment showed that the number of vases found during the session is
      not related to the presence measured during the experiment.
         The paper shows that the presence counter based on BiP is a valid measure of presence
      for HMD technology and environment containing moving by walking for small distances and
      teleportation for significant ones. The presence counter provides the same measure of presence
      as the ITC-SOPI, which showed the high level of internal consistency in the Russian-language
      sample group. The formula based on continuous time seems to be more productive, especially
      since time is actually a continuous quantity, not a discrete one. The obtained results can be
      improved when we perform the study with largest group and clarify the discriminator question.
         Thus, the results show that calculating the probabilities of presence using a formula designed
      for high presence conditions for continuous time Markov chain with the relaxation time taken
      equal to 5 seconds is optimal and allows to create the most sensitive presence counter. However,
      the experimental procedure allows for uncertainty in the subjects’ responses to the discriminator
      question whether they felt a presence. Therefore, it was necessary to use both the formula for
      high-presence conditions and the formula for low-presence conditions for undecided participants.
      It will be profitable to find a more strict discriminator question that does not give uncertainty.
      Moreover future works include the improvement of instructions. The fact that the presence
      counter calculated on the basis of BiP has a significant correlation with the three of ITC-SOPI
      scales, that is, not only with “Sense of Physical Space”, but also with “Ecological Validity” and
      with “Engagement”, looks very interesting. Obviously, the presence counter measures how
      much the participant feels in the virtual environment and also how much they perceive the
      environment as plausible and natural. The presence counter also measures how much the
      participant is involved in the events of the environment.
         Future research should also include virtual experiences related to different environments,
      participants’ capabilities, and tasks. When the procedure for applying the presence counter
      is clarified, it will be possible to raise the question of the relationship between the presence
      deducted using the BiP-based presence counter and various individual characteristics of partici-
      pants, such as gender of respondents, age, degree of familiarity with virtual reality, attitudes
      associated with participation in the experiment and so on.
IMS-2021. International Conference “Internet and Modern Society”                                         437




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