Being present in more than one place at a time? Patterns of mental self-localization

Abstract

Research in cognitive neuroscience and spatial presence suggests that human mental self-localization is tied to one place at a given point in time. In this study, we examined whether it is possible to feel localized at two distinct places at the same time. Participants (N = 30) were exposed to a virtual rollercoaster and they continuously judged to what extent they felt present in the immediate environment and in the mediated environment, respectively. The results show that participants distributed their self-localization to both environments, and the two values added up to closely 100% over time. In addition, even though the judgments are highly idiosyncratic, they were almost perfectly inversely related. This indicates that individuals can distribute their self over two distinct places. These findings provide important insights about understanding of the human self-localization.

Introduction

The term bilocation describes instances in which an individual is located in two distinct places at the same time. Pythagoras who was believed to be a manifestation of the god Apollo – was seen on the same day at the same time in both Metapontum and Croton. Incidences of bodily bilocation are reported in different cultural and religious contexts such as Buddhism, folklore, mysticism, shamanism, and have inspired the creation of several novels and movies (e.g., “Against the Day”, “Poltergeist”). Despite the fact that the phenomenon of bilocation does not exist physically it remains unclear whether at all, and if so to what extent the human mind allows for simultaneously locating oneself mentally at different places.

In particular, the use of modern media technologies raises the question whether users can mentally locate themselves in two spatially distinct places at the same time. During the Lindbergh Operation, for example, surgeons in New York successfully completed a tele-surgical operation on a patient in Strasbourg (Marescaux et al., 2001). Various studies suggest that during teleoperations people feel located in remote places (e.g. Ruff, Narayanan, & Draper, 2002). Therefore, technological development gives rise to a particular experience: The sensation of being spatially present – or self-localized – at remote places displayed by technical interfaces. In 1980, Minsky introduced the term “telepresence” and he believed that telepresence can be a true substitute for the “real thing“. Indeed, subsequent research showed that many applications bear the potential to elicit sensations of spatial presence such as online games (Weibel, Wissmath, Habegger, Steiner, & Groner, 2008), teleoperations (e.g., piloting an unmanned aerial vehicle, Ruff et al., 2002), cybertherapy settings (Price & Anderson, 2007), video conferencing (Anderson, Ashraf, Douther, & Jack, 2001) or IMAX movies (Lombard & Ditton, 1997). Sadowsky and Stanney (2002) described presence as “a sense of belief that one has left the real world and is now ‘present’ in the virtual environment” (p. 791). Therefore, self-localization is a central aspect of presence. Biocca (1997) claimed that at one point in time, users feel present in either the physical environment, the virtual environment, or the imagined environment. Thus, presence in virtual environments implies the “departure” from the physical environment and the “arrival” in the mediated environment (Kim and Biocca, 1997, Sadowsky and Stanney, 2002, Steuer, 1992), with departure being a necessary precondition for arrival. Wirth et al. (2007) postulated a similar definition of presence. Their model assumes that self-localization is the result of perceptual hypothesis testing (two competing hypotheses: being “here” vs. being “there). Spatial presence will be experienced (1) when the users accept the medium as primary egocentric reference frame and (2) when they reject the immediate environment as primary egocentric reference frame. In other words, self-localization in the mediated environment is the consequence of confirming a particular perceptual hypothesis. It is noteworthy that Wirth et al.’s model also postulates that self-localization must be limited to one point in space at a given time (i.e., either in the immediate physical or in the mediated environment). Therefore, this definition of spatial presence implies that it is a binary experience: individual’s perceived self-localization is either in the physical or in the mediated environment.

Interestingly, the topic of self-localization is also being investigated in cognitive neuroscience. In particular, reports of out-of-body experiences (OBE) have inspired several studies, which provide compelling demonstrations that the physical body does not necessarily constrain mental self-localization (e.g., Blanke et al., 2004, Brugger et al., 1994). During an OBE, one feels located outside one’s own physical body, and some people experience a rapid alternation of the self-localization between an outside and an inside position. Even though OBE’s have been reported in clinical cases such as epilepsy, migraine, neoplasia, or psychiatric disorders (cf. Blanke et al., 2004) it has to be mentioned that OBEs can be experienced by healthy individuals and the lifetime prevalence of which is nearly 10% (Blackmore, 1982, Irwin, 1985).

Lenggenhager, Tadi, Metzinger, and Blanke (2007) used conflicting visual and somatosensory input to disrupt the spatial unity of the self and the body. Their experimental paradigm can be seen as a full body version of the “rubber hand illusion” demonstrated for the first time by Botvinick and Cohen (1998). Participants mislocalized themselves towards a visually presented virtual body (i.e., they located themselves between their own physical and the virtual body). These findings provide further empirical evidence that self-localization may be outside the bodily borders. Riva (2007) interprets Lenggenhager et al.’s findings as evidence for telepresence induced by virtual reality (VR): “The subjects were no longer present in their real body but were instead in the synthetic body produced by VR. In short, the researchers used virtual reality to induce telepresence” (p. 1041). A more recent study by Slater, Spanlang, Sanchez-Vives, and Blanke (2010) is in line with Riva’s conclusion.

In this study, we follow up on the essential questions Lenggenhager et al.’s (2007) design brought up: Are the methods to assess self-localization a valid indicator for the place where the participants actually felt localized? Or is the indicated location rather the result of a compromise between two competing self-localizations? The fact that the participants reported feelings of “weirdness” could – at least in part – be caused by them having to integrate two conflicting spatial inputs (i.e. “this is the place where I saw myself and this is the place where I felt myself being touched”) into one single place. This possible limitation is also true for more sophisticated measures such as the mental ball dropping test (Indovina et al., 2005, Lenggenhager et al., 2009) that allows for assessing self-localization during manipulation. Even though this measure has the advantage to capture self-localization over time it again constrains the participant to choose one single locus of the self.

Lenggenhager et al. (2007) state that self-localization is a combination of bottom-up and top-down processes. Since not only automatic sensory integration but also cognitive processes are involved and different layers of the self have been proposed (e.g., Metzinger, 2007), it is at least conceivable that individuals are able to experience more complex patterns of self-localization. For example, the operator of an unmanned aerial vehicle may be able to simultaneously distribute his or her self-localization over two places. On the one hand, he or she pilots the vehicle as if on board, on the other hand she or he is fully aware that the physical body is away from possible harms thus allowing for more risky operations when compared to a pilot who is physically exposed to the battlefield.

In this study we want to investigate in more detail the phenomenon of self-localization. To date, empirical studies on self-localization are still scarce, and, to our knowledge, the temporal dynamics of the self-localization process have not yet been addressed. Therefore, participants continuously indicate to which degree they feel located in the mediated environment and in the immediate reality respectively. Based on previous research reported above one would assume that human mental self-localization is limited to a single location at a given point in time. We hypothesize that participants will localize themselves either in the immediate physical environment or in the mediated environment. We use a measure that (1) can be used online during exposure to the mediated environment, (2) enables to capture the temporal dynamics, and, most importantly, (3) allows for the assessment of a possible bilocalization.