# Impact of group synchrony, postural stability and agency on cybersickness symptoms

Julia Ayache, Camille Pistre, Pierre Jean, Anna Katharina Hebborn, Didier

Stricker, Benoit Bardy

► To cite this version:

Julia Ayache, Camille Pistre, Pierre Jean, Anna Katharina Hebborn, Didier Stricker, et al. Impact of group synchrony, postural stability and agency on cybersickness symptoms. EuroXR 2024, Nov 2024, Athènes, Greece. 2024. [hal-04846162](https://hal.science/hal-04846162v1)

HAL Id: hal-04846162

https://hal.science/hal-04846162v1

Submitted on 18 Dec 2024

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<figure><img src="image_1.png" /></figure>
## BACKGROUND

More than 50% of users report cybersickness symptoms when they first immerse in Virtual Reality (VR) [1]. Therefore, despite technological advances, cybersickness remains a challenge impeding the adoption of VR.

The postural instability hypothesis suggests that cybersickness could result from postural instability [2]. Interestingly, postural stability is often studied in single individuals, while studies [3,4] reported an increase of postural stability when moving in synchrony with others.

→ Does group synchrony could increase postural stability and reduce cybersickness?

## METHODS

7 triads (N = 21) completed oscillatory movements with their right arm in VR under three conditions; manipulating visual coupling (SOLO) and synchronization instructions (TOGETHER and SYNCHRO).

<figure><img src="image_2.png" /><figcaption>Illustration of the virtual environment and avatar representations</figcaption></figure>

→ Group and individual synchrony scores were extracted using the Kuramoto model [5].

→ Postural stability was computed from the normalized length of head motion on the anteroposterior and mediolateral directions [6].

→ Cybersickness symptoms were measured before and after each condition with the Simulator Sickness Questionnaire (SSQ, [7]).

→ Sense of agency (SoA) was measured after each VR immersion using the Sense of Agency Scale (SoA, [8]).

## RESULTS

<figure><img src="image_3.png" /><figcaption>HEAD MOTION - SOLO CONDITION</figcaption></figure>

<figure><img src="image_4.png" /><figcaption>GROUP SYNCHRONY - TOGETHER CONDITION</figcaption></figure>

<figure><img src="image_5.png" /><figcaption>HEAD MOTION - TOGETHER CONDITION</figcaption></figure>

<figure><img src="image_6.png" /><figcaption>GROUP SYNCHRONY - SYNCHRO CONDITION</figcaption></figure>

<figure><img src="image_7.png" /><figcaption>HEAD MOTION - SYNCHRO CONDITION</figcaption></figure>

<figure><img src="image_8.png" /></figure>

Graphical representations of the impact of the experimental conditions SOLO (top), TOGETHER (middle) and SYNCHRO (bottom) on group synchrony scores (left) and body sway (right)

Mixed models showed that the experimental conditions influenced:

→ Group synchrony scores (F (2, 96) = 107.36, *p* < .001), with an increase of group synchrony when participants could see each other and were instructed to synchronize (SYNCHRO condition, adjusted *p* < .001).

→ Postural stability (F (2, 310) = 3.28, *p* = .039), with a decrease of body sway in the SYNCHRO condition (adjusted *p* = .055).

However, there was no effect of the experimental manipulation on cybersickness symptoms (F (2, 58) = 0.17, *p* = .847) and sense of agency (F (2, 58) = 0.71, *p* = .494) but a tendency for a negative correlation between cybersickness symptoms and sense of agency (*r* = -.21, *p* = 0.09).

## DISCUSSION

This study demonstrated (i) the role of visual coupling and instructions to synchronize in VR [5], (ii) the impact of group synchrony on postural stability beyond dyads [3,4].

While there was no impact of synchrony nor body sway on cybersickness, this study reports a possible association of agency with cybersickness.

→ This finding paves the way for exploring the role of temporal binding between actions and their consequences on cybersickness in social VR.

This project has received funding from the European Union's research and innovation program Horizon Europe under grant agreement No 10192889

<figure><img src="image_9.png" /></figure>

## REFERENCES

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[2] Riccio, G. E., & Stoffregen, T. A. (1991). An ecological theory of motion sickness and postural instability. Ecological psychology, 3(3), 195-240.

[3] Gueugnon, M., Salesse, R. N., Coste, A., Zhao, Z., Bardy, B. G., & Marin, L. (2016). Postural coordination during socio-motor improvisation. Frontiers in psychology, 7, 1168.

[4] Varlet, M., Marin, L., Lagarde, J., & Bardy, B. G. (2011). Social postural coordination. Journal of Experimental Psychology: Human Perception and Performance, 37(2), 473.

[5] Alderisio, F., Fiore, G., Salesse, R. N., Bardy, B. G., & Bernardo, M. D. (2017). Interaction patterns and individual dynamics shape the way we move in synchrony. Scientific reports, 7 (1), 6846.

[6] Laroche, J., Tomassini, A., Volpe, G., Camurri, A., Fadiga, L., & D'Ausilio, A. (2022). Interpersonal sensorimotor communication shapes intrapersonal coordination in a musical ensemble. Frontiers Frontiers in human neuroscience, 16, 899676.

[7] Bouchard, S., Robillard, G., & Renaud, P. (2007). Revising the factor structure of the Simulator Sickness Questionnaire. Annual review of cybertherapy and telemedicine, 5(Summer), 128-137.

[8] Hurault, J. C., Broc, G., Crône, L., Tedesco, A., & Brunel, L. (2020). Measuring the sense of agency: a French adaptation and validation of the sense of agency scale (F-SoAS). Frontiers in Psychology, 11, 584145.