https://orcid.org/0000-0001-5389-9900
Figures
Abstract
A growing body of literature has found that synchronising movements with a group subsequently increases self-other blurring and social closeness with synchronised partners. However, movement synchrony has not been studied in online settings. Our study has a primarily methodological focus to investigate whether synchronous movement leads to changes in self-other blurring and proxemics in an online, desktop-mediated environment. We conducted two experiments to manipulate synchrony with a group of virtual agents and investigate its impact on self-other blurring and comfort distance judgments. In Experiment 1, we compared synchronous movement to a no-movement condition; in Experiment 2, we introduced an unpredictable movement condition. In both experiments, we found that our manipulation of synchronous movement between participants and a virtual group of agents led to an increase in explicit self-other blurring compared to the no and unpredictable movement conditions; however, we did not find reliable effects on comfort distance judgments.
Citation: Biswas M, Brass M (2024) Syncing online: A methodological investigation into movement synchrony, proxemics, and self-other blurring in virtual spaces. PLoS ONE 19(10): e0308843. https://doi.org/10.1371/journal.pone.0308843
Editor: Merryn D. Constable, Northumbria University, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
Received: April 10, 2024; Accepted: July 31, 2024; Published: October 22, 2024
Copyright: © 2024 Biswas, Brass. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Data Availability: All data files files are available from the OSF database (10.17605/OSF.IO/S78FK).
Funding: MBi was supported by the German Academic Exchange Service (DAAD; German: Deutscher Akademischer Austauschdienst) (https://www.daad.de/en/). Additionally, this study was funded by DAAD, German Research Foundation (Deutsche Forschungsgemeinschaft, DFG) (https://www.dfg.de/en) under Germany's Excellence Strategy-EXC 2002/1, Science of Intelligence (Project Ref.: 390523135) and the Einstein Foundation Berlin (https://www.einsteinfoundation.de/en/). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests: The authors have declared that no competing interests exist.
Introduction
Background
Interpersonal synchronous movement is a universal characteristic of human collective behaviour [1] and is often accompanied by a euphoric sense of union [2]. Rituals that incorporate collective movement play a key role in the evolution of human ultrasociality by facilitating the maintenance of large cohesive groups [2–13]. Previous research suggests that interpersonal synchrony expands the contours of the group beyond the confines of familial relationships [14] and physical similarity [15] by utilising behavioural movement patterns as cues of similarity for in-group bond formation [14–21]. In a similar vein, the study of interpersonal space (also known as proxemics), has found that in-group affiliation plays a significant role in how we moderate the space around us [22]. Interpersonal distance [23, 24] and movement synchrony [25, 26] have been previously examined using augmented and virtual reality paradigms. For example, Dotsch & Wigboldus [27] found that Dutch participants maintained more distance and showed higher levels of stress-induced skin conductance when they encountered an avatar with Moroccan facial features as opposed to Caucasian features. Thus, in-group categorisation manifests in terms of interpersonal distance as differing levels of comfort. The closer we feel towards someone the further they are allowed to approach into our personal space (for review [28]). Virtual agents presented via a desktop-computer also impact interpersonal space modulation. For example, Fini et. al. found a social scaling mechanism for extra-personal space in a 3D desktop experiment [29]. Virtual agents capable of movement, as opposed to wooden dummies, were judged as being nearer, indicating a near space extension contingent on the movement potentialities of the other agent. Furthermore, in an immersive virtual reality experiment Tarr et. al found that moving synchronously with virtually presented agents as opposed to asynchronously increases social closeness [26].
Link between synchrony and proxemics
Shared motor experience leads to remapping of personal space. Following synchronous multisensory stimulation, partners are more readily placed within one’s own peri-personal space [30]. In a study by Jackson et. al, large groups marched either synchronously or asynchronously from one another and in a subsequent dispersal task, groups that marched synchronously tended to stand closer to each other [5]. Furthermore, Tunçgenç & Cohen (2016) found that synchronous movement conditions showed higher bonding, expressed via increased physical proximity in the Island Game [21]. Collectively these studies indicate that the affiliative tendencies that arise out of synchronous movement can be expressed in terms of modulations of interpersonal distance (proxemics). A potential theoretical link between synchrony and interpersonal space modulation is that they both rely on the mechanism of self-other blurring to facilitate affiliation [20, 31–33]. Cooperative and affiliative actions that arise from a ‘striving to integrate the self into a larger social unit’ [34] are often expressed in terms of self-other blurring.
Studies that induced synchrony through tapping [7, 35–39], arm-curls [18, 40, 41], bouncing of infants [42–45], limb and arm movement [18, 32], stepping [20], dancing/full body movements [21, 33, 39, 46], singing [9, 35, 47, 48] or swinging [49] found that movement synchronisation is correlated with higher self-reported scores on subjective measures of self-other blurring. Cross et. al. argue that synchrony elicits affiliative tendencies through self-other blurring via recategorization of self and other as common group members, that is, shared synchronous movement facilitates social bonding by re-categorising perceptions of self and co-actor through low level appraisals of similarity [40, 41, 50]. Similarly, research in proxemics has shown that following fair and cooperative interactions in an economic game, peri-personal space boundaries between self and other merged [22]. The existence of this theoretical backing, compounded by the finding that synchronous stimulation [30] and movement [21] leads to modulations of interpersonal space, make a strong case for the investigation of how synchronous movement might impact interpersonal space modulation.
Online mediated synchrony
The aim of the current study is to investigate whether avatar-mediated synchrony can reliably reproduce affiliative tendencies and to investigate its impact on interpersonal space modulation in an online desktop environment.
In general, social psychological research can be transmitted to the online environments as virtual agents elicit social experiences comparable to real social interactions [23]. Conducting psychological research online offers benefits such as a substantial increase in the number of participants and tightly controlled experiments, ensuring a universal experience for all participants. By leveraging the online nature of our study, we secured a remarkable preregistered sample size (total n = 870 participants), unprecedented in synchrony research.
Most studies on synchrony have been conducted in face-to-face and desktop settings wherein participants move their bodies to achieve interpersonal synchrony with virtually presented agents (see for example, [51]). In our study we employ an avatar mediated experience of synchrony, see Fig 1. It is important to consider that there may be psychological differences between a mediated and an unmediated experience of synchronous movement. Unmediated experiences involve participants performing identical movements to the group’s with their own bodies. In contrast, mediated experiences involve no real correspondence of movements between participants and the interacting group presented online. The interpersonal synchrony that emerges only exists between a controlled avatar and a group of agents. We designed our experiment to investigate whether synchrony induced affiliation can occur in mediated settings and to infer the extent of the effects, specifically, whether synchronous movement can produce both explicit self-other blurring and implicit interpersonal space modulation.
Current study
Our experiment consists of 2 dependent measures; an explicit measure of self-other blurring (IOS Scale) and an implicit measure of proxemics, calculated by averaging the responses on the stop-distance task. It should be also noted that while IOS scale is a widely used indicator of self-other blurring, there are mixed findings regarding its relationship with synchrony. Some studies have found that it did not mediate the relationship between synchrony and in group bonding [13], whereas others did [52–54].
We instructed participants to synchronise the movement of their avatar to a 60-bpm metronome beat by pressing a button. They were not directly instructed to synchronise their movement with the group of virtual agents and the synchrony that arose was incidental. In previous studies it has been shown that synchrony can produce affiliative tendencies even when synchrony is incidental to the main task [36], even though participants realised that this resulting synchrony was only due to external circumstances, they reported liking partners who had been in sync with them more than asynchronous partners. Some studies, however, found no effects or more complex effects relating to incidental synchrony (see [54, 55]).
To investigate proxemics, we used the stop distance paradigm [56] sometimes also referred to as the “comfort distance under passive approach” task. In this task a group of agents approaches the participant’s avatar and the participant is instructed to press a button to indicate at which point the diminishing distance between their avatar and the group makes them feel uncomfortable, see Fig 2. In the synchrony condition, we expected to see a comfort distance extension, as opposed to the condition wherein the agent group either showed no movement or moved in an unpredictable manner. That is, our hypothesis was that following shared synchronous movement, the participant would allow the agent group to approach their avatar at a closer distance before reporting discomfort. In the second experiment, to rule out the possibility that the effect was simply due to the presence of movement and not shared synchronous movement we added an unpredictable movement condition, wherein the four characters in the agent group move independently of each other and the participants’ avatar, that is, they performed random actions at random times, see last panel of Fig 1. This condition also allows us to manipulate the predictability of action identity, an essential component of synchronous movement [57]. Even though both movement identity and temporal phasic relations contribute to synchrony, most synchrony paradigms exclusively manipulate the latter of these components by changing the timing of movement in agents to create an asynchronous rhythm. By introducing an unpredictable movement condition, we further extend the current understanding by manipulating both movement identity and time predictability.
Distances at which participants stopped the agents were recorded to measure comfort distance judgements.
Experiment 1
Methods
Details of the experiment were pre-registered [https://osf.io/5ytmq].
Participants.
We collected the data of 457 participants (198 female, 5 non-binary, Mage = 28.7, SDage = 9) from Prolific. 97 participants were excluded based on our pre-registered exclusion criteria (69 for > = 10 comfort distance judgements out of range, 21 for missing > = 3 catch trials and 7 for meeting both criteria). Participants that did not meet the exclusion criteria were replaced to ensure that 360 participants remained after the exclusion criteria were applied (156 female, 5 non-binary, Mage = 28.7, SDage = 9). In accordance with the expected directional effects, we based our sample size on a one tailed dependent t-test power analysis where we estimated a small effect size (d = 0.3) for our implicit dependent measure. All participants were naïve to the aims of the experiment and compensated at a rate of 6 £/hr for their time. Participants provided informed consent before they began the experiment. The experiment was approved by the ethical review board at the Institute of Psychology, Humboldt University of Berlin.
Design and procedure.
The experiment was programmed on Unity and administered hosted online using JATOS (Just Another Tool for Online Studies). It comprised 2 groups of participants: the experimental group exposed to the synchronous movement condition and the control group exposed to the no movement condition. Each experimental block consisted of 2 parts, Synchrony manipulation and Stop Distance Task. Participants began with a practice block wherein they received feedback (1) if they did not synchronise their button presses with the audio cue and (2) if they did not follow the instructions during the stop distance trials, that is, if they reported discomfort as soon as the trial began or if they did not report until the trial ended (when agent group was face-to-face with their avatar). The practice block was followed by 5 experimental blocks, thus there were a total of 25 stop distance judgments provided by each participant. Following this, the participants answered the IOS (Inclusion-of-other-in-self) scale [31],a self-reported indicator of perceived overlap between self and other. Then participants were redirected to prolific and compensated for their time. The experiment took approximately 15 minutes to complete.
Synchrony manipulation.
Each block began with the synchrony manipulation, participants were presented with an avatar that they could control by pressing the space bar and they were instructed to press the spacebar when they heard an audio cue. The audio cue was presented 13 times per block at a rhythm of 60 bpm. When participants pressed the spacebar, their avatar moved in the jumping-jacks motion, see Fig 1. The jumping jacks movement animation took approximately 900 ms to complete. A group of 4 agents (2 male, 2 female) faced the participant’s avatar and depending on the condition assigned to the participant, the agents either moved synchronously with their avatar or were in idle pose while their avatar moved. When participants heard the first three beeps and subsequently pressed the button, their avatar moved alone to facilitate embodiment, followed by 10 beeps during which the agent group either moved synchronously with the avatar or did not move, see Fig 1.
Stop distance task.
In the stop-distance task, the same group of agents that had been previously presented began walking toward the participant’s avatar. Participants were instructed to press the spacebar to stop the approaching group when the diminishing interpersonal distance made them feel uncomfortable. Once the participants reported discomfort, the agent group stopped and then disappeared. In the next trial, they reappeared in their original position and once again began approaching their avatar. Each Stop Distance trial could last up to approximately 5 seconds if the participant did not respond, once the participant responded the trial ended and the next one began. This was repeated 5 times per block. The camera position was jittered for each repetition to prevent participants from explicit strategies, see Fig 2.
Statistical analysis.
We coded the stop distance task such that the distance between the agent group and the avatar ranged between 0–100. A judgement at 0 was indicative of participant’s waiting too long to report discomfort and a judgement larger than 90 was indicative of the participant reporting discomfort as soon as the trial began. We chose 90 as the threshold because a response earlier than 90 meant that the participant responded before the group had moved from their original position. Thus, as per our pre-registration, judgments that were larger than 90 and at 0 were removed. Valid stop distance trials were used to calculate an average comfort distance per participant. Participant’s response on the Self-Other blurring scale served as their IOS score. Analyses were conducted on Python, R (version 4.2) and Jamovi (version 0.16.2).
Results
Self-other blurring.
The IOS or Inclusion of Other in Self scale is a self-reported indicator of perceived overlap between self and other (in this case, a group of agents). We compared IOS Scale scores across the Synchronous Movement and No Movement conditions. The IOS scores did not follow a normal distribution as indicated by the Shapiro-Wilk test (Sync: W = 0.883, p < .001; No Movement: W = 0.806, p < .001) and variances were not equal according to Levene’s test (p < .05). Results showed that IOS scores were significantly higher in the Synchronous Movement condition (Sync: M = 2.644, Mdn = 3, SD = 1.519, Range = 1–7) as compared (U = 19,122, p < .001, Z = 2.96) to the No Movement condition (No Movement: M = 2.178, Mdn = 2, SD = 1.383, Range = 1–7) in a directional Mann-Whitney U test (Synchronous Movement > No Movement), see Fig 3.
Error bars represent standard errors.
Comfort distance.
Mean Comfort Distance refers to the average distance at which the participant stopped the approaching group. Mean Comfort Distances were not normally distributed according to the Shapiro-Wilk test (Sync W = 0.943, p < .001; No Movement W = 0.915, p < .001). The significant effect we found was contrary to that which we hypothesised, i.e., (Synchronous Movement < No Movement). In a Mann-Whitney U test (Synchronous Movement > No Movement), Mean Comfort Distance following the Synchronous Movement (M = 0.339, Mdn = 0.284, SD = 0.200, Range = 0.041–0.816) were significantly greater (U = 17,983, p < 0.05, Z = 1.805) than those following No Movement (M = 0.302, Mdn = 0.262, SD = 0.195, Range = 0.043–0.846), see Fig 3.
Exploratory analyses
Correlating explicit and implicit measures.
To establish whether there was a relationship between self-other blurring and comfort distance judgments, we correlated IOS and CD variables across participants. As the data was not normally distributed, we report Spearman’s rank order correlation. To correct for multiple comparisons, we also report corrected p values using the Holm–Bonferroni method.
We found no correlation between them when data was collated across conditions [r = -0.060, 95% CI [0.043, -0.163], p = 0.25]. As pre-registered, we also sub-set the data based on condition. Synchronous Movement: We found no significant correlation between IOS and CD variables when only the synchronous movement condition was analysed [r = 0.066, 95% CI [0.211, -0.081], p = 0.376]. No Movement: We found a significant correlation between IOS and CD variables when only the no movement condition was analysed, [r = -0.226, 95% CI [-0.083, -0.361], p = 0.002, corrected p = 0.006], see Fig 5.
Post-task variables: Embodiment, strategy use and purpose check.
We pre-registered the intention to check if any of the post-task questions might explain some of the variance in the data. Specifically, we were interested in Embodiment, Strategy Use and Purpose Check. None of these factors had any significant impact on our variables of interest, for a detailed report please consult Section 1 of the supplementary materials.
Experiment 2
Results from the Experiment 1 indicate that we were able to reproduce self-other blurring in the online context, contrasting our hypothesis we found that comfort distance judgements were greater for following synchronous movement as opposed to no movement. We conducted Experiment 2 to replicate our unexpected finding regarding the relationship between synchronous movement and proxemic judgements and to investigate the relationship between IOS Scores and Comfort distance judgements. Furthermore, the effects found in Experiment 1 might be merely as a result of the perception of movement in the agent group and not synchronous movement per se. We addressed this concern by adding a new condition wherein the agent group moved in an unpredictable manner, that is, they moved at random times and performed a random action from a set of predetermined actions, see last panel of Fig 1.This experiment had one between-subjects factor: Agent Movement which varied at 3 levels, Synchronous movement, No movement and Unpredictable movement. The procedure was the same as Experiment 1. We asked participants to press the spacebar as soon as they heard the audio cue and report discomfort in the stop distance task.
Methods
Experiment 2 was pre-registered [https://osf.io/n7ruq]. The procedure was the same as Experiment 1.
Participants.
574 subjects were recruited through prolific. We excluded 64 participants based on pre-registered exclusion criteria (24 for missing > = 3 catch trials, 36 for > 10 comfort distance judgements out of bounds and 4 for meeting both criteria). Excluded subjects were replaced to ensure that 510 subjects remained (245 female, 3 non-binary, 2 no answer; Mage = 37.94, SDage = 11.20). 170 participants per condition, in accordance with the expected directional effects we based our sample size on a one tailed dependent t-test power analysis of our data from Experiment 1 at a significance level of 0. 025 to correct for multiple comparisons, as we plan to conduct two independent t-tests on the data.
Design and procedure.
The experiment consisted of three groups of participants: the synchronous movement group, the no movement group, and the unpredictable movement group. As before, each experimental block consisted of two parts: Synchrony manipulation and Stop Distance Task.
Synchrony manipulation.
Synchrony and No movement condition were identical to Experiment 1. We added a new condition, Unpredictable movement. In this condition, the participant heard the audio cue and when they pressed the spacebar, their avatar moved. The 4 agents facing their avatar moved randomly during the action task, that is each of the agents acted at random times within the block and when they moved, they produced a variety of random motions, see Fig 1. Thus, each of the agents moved independently of each other and independently of the movement produced by the participant’s avatar.
Statistical analysis.
As we did not have a hypothesis relating to the relationship between No movement and Unpredictable movement condition, we opted to conduct two t-tests. One that compared the No movement and the Synchronous movement conditions, which would help us reproduce our findings from Experiment 1. The other between the Synchronous movement and Unpredictable movement condition which would help us discern whether the effect was due to the mere perception of movement in the agent group. Since we are conducting two t-tests, we will set our significance level at 0.025 to correct for multiple comparisons.
Results
Self-other blurring.
Synchrony and no movement. IOS scores were not normally distributed according to the Shapiro-Wilk test (Sync W = 0.920, p < .001; NoMove W = 0.832, p < .001). Results showed that IOS scores were significantly higher in the Synchronous Movement condition (Sync: M = 3.18, Mdn = 3, SD = 1.61, Range = 1–7) as compared (U = 18,059.5, p < .001, Z = 3.98) to the No Movement condition (No Movement: M = 2.5, Mdn = 2, SD = 1.64, Range = 1–7) in a directional Mann-Whitney U test (Synchronous Movement > No Movement), see Fig 4.
Error bars represent standard errors.
Synchrony and unpredictable movement. IOS scores were not normally distributed according to the Shapiro-Wilk test (Sync W = 0.920, p < .001; Unpredictable W = 0.895, p < .001). Results showed that IOS scores were significantly higher in the Synchronous Movement condition (Sync: M = 3.18, Mdn = 3, SD = 1.61, Range = 1–7) as compared (U = 16367.5, p < .05, Z = 2.12) to the Unpredictable Movement condition (Unpredictable: M = 2.82, Mdn = 2.5, SD = 1.60, Range = 1–7) in a directional Mann-Whitney U test (Synchronous Movement > Unpredictable Movement), see Fig 4.
Comfort distance.
Synchrony and no movement. Mean Comfort Distance (CD) scores were not normally distributed according to the Shapiro-Wilk test (Sync W = 0.952, p < .001; No Movement W = 0.958, p < .001). Results showed that Mean Comfort Distances were not significantly lower in the Synchronous Movement condition (Sync: M = 0.31, Mdn = 0.28, SD = 0.18, Range = 0.046–0.786) as compared (U = 13562.0, p = 0.164, Z = -0.98) to No Movement condition (No Movement: M = 0.32, Mdn = 0.31, SD = 0.17, Range = 0.042–0.813) in a directional Mann-Whitney U test (Synchronous Movement < No Movement), see Fig 4.
Synchrony and unpredictable movement. Mean Comfort Distance (CD) scores were not normally distributed according to the Shapiro-Wilk test (Sync W = 0.952, p < .001; Unpredictable Movement W = 0.955, p < .001). Results showed that Mean Comfort Distances were not significantly lower in the Synchronous Movement condition (Sync: M = 0.31, Mdn = 0.28, SD = 0.18, Range = 0.046–0.786) as compared (U = 13,132.0, p = 0.073, Z = -1.45) to the Unpredictable Movement condition (Unpredictable: M = 0.34, Mdn = 0.31, SD = 0.18, Range = 0.027–0.829) in a directional Mann-Whitney U test (Synchronous Movement < Unpredictable Movement), see Fig 4.
Exploratory analyses
Co-relating explicit and implicit measures.
To establish whether there was a relationship between self-other blurring and comfort distance judgments, we correlated IOS and CD Scores across participants. Since the data was not normally distributed, we report Spearman’s rank order correlation. Deviating from our previous findings, we found a significant correlation between IOS and mean comfort distance judgements [r = -0.117, 95% CI [-0.201, -0.030], p = 0.008], see Fig 5.
Post-task variables: Embodiment, strategy use and purpose check.
We pre-registered the intention to compare if any of the post-task questions might explain some of the variance in the data. Specifically, we were interested in Embodiment, Strategy Use and Purpose Check. None of these factors had any significant impact on our variables of interest, for a detailed report please consult section 2 of the supplementary materials.
Pooling data from Experiment 1.
In accordance with our pre-registration, we pooled the data from Synchronous movement and No Movement conditions with our data on these conditions from Experiment 1 to explore whether having a more powered study could elicit the effects. After pooling (N = 700), in accordance with the previous findings of our study while the IOS scores differed significantly across conditions, mean comfort judgements did not. IOS scores were not normally distributed according to the Shapiro-Wilk test (Sync W = 0.905, p < .001; No Movement W = 0.820, p < .001). Results showed that IOS scores were significantly higher in the Synchronous Movement condition (Sync: M = 2.90, Mdn = 3, SD = 1.59) as compared (U = 74,484, p < .001, Z = 4.95) to the No Movement condition (No Movement: M = 2.33, Mdn = 2, SD = 1.52) in a directional Mann-Whitney U test (Synchronous Movement > No Movement).
Mean Comfort Distance (CD) scores were not normally distributed according to the Shapiro-Wilk test (Sync W = 0.947, p < .001; NoMove W = 0.940, p < .001). Results showed that Mean Comfort Distances were not significantly lower in the Synchronous Movement condition (Sync: M = 0.32, Mdn = 0.28, SD = 0.19) as compared (U = 63074.0, p = 0.752, Z = 0.68) to the No Movement condition (No Movement: M = 0.31, Mdn = 0.28, SD = 0.19) in a directional Mann-Whitney U test (Synchronous Movement < No Movement).
Since the data was not normally distributed, we report Spearman’s rank order correlation. In the pooled data we found no significant correlation across participants between IOS and mean comfort distances [r = -0.051, 95% CI [0.024, -0.124], p = 0.181]. While the negative correlation is in the hypothesised direction, higher IOS reports are related to lower comfort distances, indicating the greater self-other blurring was related to allowing the group of avatars to approach at closer distances. However, this effect did not reach significance.
Discussion
Self-other blurring in mediated virtual synchrony
We hypothesised that synchronous jumping jacks movement between a desktop computer mediated avatar controlled by the participant and a group of virtual agents would elicit self-other blurring. Synchrony related self-other blurring has only been found either in real life settings wherein both participant and partner(s) are present [46, 58, 59] or the participant synchronises their own body movements to a partner presented on a computer screen or in VR setting [7, 18, 40, 41, 60, 61]. These paradigms involve the participant synchronising their own body movements, in situ, to a partner’s body movements. Thus, it was yet to be established whether it is possible to induce synchrony related affiliative tendencies in an experimental paradigm wherein the participant’s movement is translated onto an embodied avatar presented via a desktop computer. We found that synchronous movement between an avatar and a group of virtual agents leads to self-other blurring in online settings. In our first experiment, self-other blurring was greater in a shared synchronous movement condition as compared to a no movement condition. To the best of our knowledge, this is the first demonstration of self-other blurring through avatar controlled synchrony. It demonstrates that self-other blurring can occur in online settings through avatar-controlled synchrony, thereby extending the concept beyond real correspondence of movements. We replicated our finding in the second experiment where added an unpredictable movement condition to control for the possibility that presence of movement was the main driver of self-other blurring. Additionally, we found that synchronous movement led to greater self-other blurring in the shared synchronous movement condition as opposed to the unpredictable movement condition, indicating that predictable synchronous movement is associated with increased self-other blurring.
Online social psychological experiments overcome traditional challenges in the field by addressing issues such as limited sample sizes and lack of control [23]. In our experiment, we obtained an exceptionally large sample size (combined n = 870). As more individuals incorporate online environments into their daily lives, it becomes crucial to understand how our social and psychological cognitive processes translate to these settings. We induced movement synchrony between the participant’s avatar and an agent group. Depending on the experimental condition, an agent group facing the participants would either move in synchrony, remain still, or move unpredictably. Our discovery that a 3D desktop-computer mediated experience of synchrony leads to self-other blurring holds significant psychological implications. Firstly, it demonstrates that even in virtual environments, temporary groups can emerge as individuals readily adopt social cues of similarity, which are commonly employed in real-life interactions to identify common ground and in-group membership. Secondly, it indicates that movement similarity serves as a behavioural cue for in-group affiliation, even when the movement is not physically performed by the individual. One possible explanation for this indirect impact of synchrony is that participants project themselves onto a controlled avatar [62] and the correspondence of movement between this embodied avatar and a group of virtual agents can elicit self-other blurring, a psychological phenomenon linked to in-group categorisation. However, it is also plausible that simply tapping in synchrony with a group is sufficient to create self-other blurring, and the presence of the avatar may not be crucial. Additional research is required to explore this aspect further and gain a better understanding of the implications.
Predictability of movement
The direct comparison of synchronous movement and unpredictable movement is novel. In their review of synchrony, Chartland & Lakin [57] define synchronous movement as comprising two major components: (1) movement identity and (2) temporal phasic (in-phase or anti-phase) relationship. Most synchrony paradigms focus on comparing and manipulating the latter of these components, that is, they create an asynchronous condition via an interacting group performing the same action at a different time/rhythm [32]. By introducing an unpredictable movement condition, we were able to tease out the contributions of the first component to synchrony—predictability of movement identity. Previous studies have noted that predictable movement identity plays a crucial role in interactional synchrony [63–65]. Our finding further consolidates this view by demonstrating that synchronous movement is associated with greater self-other blurring than unpredictable movement. Thus, predictable movement identity plays an important role in the affiliative tendencies that arise out of synchronous movement. However, the relationship between synchrony and predictability might be more multifaceted. A recent study by Ravery et al. found that both increasing complexity and synchrony were crucial for social bonding [66]. To further build on the specific contributions of movement identity, future experiments should focus on independently manipulating movement identity, complexity and timing.
Interpersonal distance in online settings
Our paradigm did not elicit a reliable synchrony related differences in comfort distance judgements and we found inconsistent results regarding the relationship between our explicit measure of self-other blurring and implicit measure of comfort distance judgements. Specifically, the measures showed a significant correlation in our second experiment but not in the first. Further, in Experiment 1 we found a significant correlation when only data from the no movement condition were analysed.
We obtained mixed results regarding the association between explicit self-other blurring and implicit comfort distance judgments. In our initial experiment, we found no significant correlation between self-other blurring and comfort distance judgments across participants. However, when we examined the data by condition, we discovered a significant negative correlation in the no movement condition. This aligns with our hypothesis that agents inducing a higher degree of self-other blurring would be allowed to approach closer to the participants’ avatars. Experiment 2 provided further support for this finding when we analysed the data across conditions. This suggests that there may be a connection between self-other blurring and implicit comfort distance judgments, but this relationship is not consistently observed across different conditions. There are two possible ways to interpret this finding, (1) indirect desktop mediated synchrony does not elicit implicit effects of proxemics or (2) our measure of proxemics does not sufficiently capture this effect. Given that naturalistic movement synchrony experiments have successfully demonstrated the impact of synchrony on preferred proximity [5, 21], it is plausible that there exists a general limitation whereby the use of virtual environments and avatars cannot replicate the proxemics-related differences associated with synchrony. In line with this view, another study utilising virtual reality (VR) as part of their research, which included physical proximity as a dependent measure (calculated as the average distance maintained throughout the experiment), found no significant differences in physical proximity [61]. Thus, there may be aspects of affiliative tendencies that arise from synchrony, which cannot be effectively replicated in online or VR settings. Although the current evidence points in this direction, further empirical studies are needed to firmly establish that proxemic differences cannot be replicated in VR or other mediated virtual experiences.
Implications for virtual synchrony and future directions
It is possible that the influence of synchrony on proxemics is difficult to capture in an online setting, and it might be more reliable to elicit this effect in a virtual reality (VR) environment. Given that the significant correlations align with our initial hypothesis, conducting another study in VR with varied experimental settings could provide a more robust test of this hypothesis. There are significant distinctions between online 3D desktop environments and VR settings. Cohen et al. discovered that when participants listened to a person sharing a painful autobiographical memory in VR, as opposed to on a computer, there was a greater sense of social presence, affiliative feelings, and facial synchrony in the VR setup [67]. Recreating our experiment in VR could potentially amplify the effects of synchronous movement, as participants would need to engage in real movement correspondence with an agent group. Furthermore, employing a VR environment for the comfort distance under the passive approach task is likely to enhance immersion, thereby increasing the potential for more pronounced implicit effects on comfort distance judgments.
In conclusion, we found that avatar-mediated synchrony with a group of virtual agents leads to self-other blurring, suggesting that real movement correspondence with a synchrony partner is not a prerequisite for in-group bond formation. We also found that predictability of movement identity contributes to self-other blurring by directly comparing synchronous movement to an unpredictable movement condition. By demonstrating that synchronised movement’s psychological effects can be recreated in virtual environments, this research highlights the potential for fostering group cohesion in online team-building and collaboration. Our findings suggest that even without physical presence, virtual spaces can support the development of cohesive online communities.
Supporting information
S1 File. This document contains detailed analyses and data regarding Experiment 1 and Experiment 2 post-task variables, including embodiment, strategy use, and purpose check.
It provides statistical comparisons of dependent variables in relation to attention checks, strategy use, and purpose.
https://doi.org/10.1371/journal.pone.0308843.s001
(DOCX)
Acknowledgments
Thanks to Valerii Chirkov (experiment development), Dr. Michael Galang (protocol advice) and Dr. Silvia Formica (revision).
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