# Virtual reality boxing: Gaze-contingent manipulation of stimulus properties using blur

Annabelle Limballe, Simon Bennett, Alexandre Vu, Richard Kulpa

► To cite this version:

Annabelle Limballe, Simon Bennett, Alexandre Vu, Richard Kulpa. Virtual reality boxing: Gaze-contingent manipulation of stimulus properties using blur. VR 2022 - IEEE Conference on Virtual Reality and 3D User Interfaces, IEE VR, Mar 2022, Virtual, New Zealand. hal-05492813

HAL Id: hal-05492813

https://amu.hal.science/hal-05492813v1

Submitted on 4 Feb 2026

HAL is a multi-disciplinary open access
archive for the deposit and dissemination of sci-
entific research documents, whether they are pub-
lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d'enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.

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

Distributed under a Creative Commons CC BY 4.0 - Attribution - International License
# Virtual reality boxing: Gaze-contingent manipulation of stimulus properties using blur

Annabelle Limballe, Simon Bennett, Alexandre Vu and Richard Kulp

<figure><img src="image_2.png" /><figcaption>Fig. 1. View of the virtual opponent in the environment.</figcaption></figure>

**Abstract—Introduction:** For more than two decades, sport scientists have investigated the contribution of perceptual-cognitive skills such as anticipation, attention and decision making to expert performance. It is now well accepted that experienced/skilled athletes in dynamic and interactive sports are better at anticipating an opponent's movement, often focus eye gaze and thereby attention with specific spatio-temporal patterns, and make earlier and more appropriate decisions [8]. Such findings have typically been reported in studies that used video stimuli viewed from a third-person perspective, but there is confirmatory evidence from simulated on-field settings [6] and virtual reality (VR) [1, 2]. Although the latter approaches offer a more realistic athlete-environment interaction, VR environments can be completely reproducible, controlled and easily manipulated, while preserving the normal perception-action loop [10]. In the current study, therefore, we studied expert combat athletes in a VR boxing setting where we manipulated: i) deceptive information at the onset of an attack; and ii) clarity of the visual display relative to gaze location. In addition to measuring outcome performance, we recorded gaze location within the VR setting, thus enabling us to determine gaze metrics when facing an attacking opponent, and if these are modified by clarity of the visual display.

**Methods:** We designed a VR boxing environment (Unity software) in which participants (practicing boxers and combat sport athletes) faced an attacking opponent within a 4x4m ring in a simulated boxing match. Participants wore an HTC Vive Eye Pro VR HMD and had motion trackers connected to both hands. They were asked to intercept and block the opponent's blows, which comprised 12 sequences of 3 punches, preceded by a foot feint, arm feint or no feint. We manipulated the visual stimuli using a gaze contingent protocol in which a Gaussian blur was applied to alter the availability of high frequency information [3, 4, 7, 11, 13]. There were 3 blur intensities (low, medium, and strong blur), which were applied over the entire display except for a window of 5° diameter around the fixation point (peripheral blur), or to a window of 5° diameter around the fixation point (central blur). Within the central and peripheral viewing condition, participants performed 2 blocks of 36 sequences (2 repeats x 12 sequences x 3 levels of blur), whereas in a control condition (no blur), they performed a block of 24 sequences (2 repeats x 12 sequences).

**Results:** Using iterative mixed modelling, we determined the simplest fixed effects that best fit the repeated measures data. For number of interceptions, the final reduced model indicated significant main effects of viewing condition ($F_{1,304}=17.33, p<.001$), punch ($F_{2,656}=25.77, p<.001$) and order ($F_{2,37}=77.16, p<.001$), as well as significant viewing condition by order ($F_{2,679}=3.40, p<.05$) and punch by order ($F_{4,834}=19.00, p<.001$) interactions. Bonferroni corrected pairwise comparisons indicated that performance in the central condition was significantly better than the peripheral condition (irrespective of the level of blur) for the first ($p<.03$) and second ($p<.001$) punch in a sequence. In addition, participants intercepted significantly more of the first punches in a sequence when they were preceded by a foot feint than arm feint ($p<.001$) or no feint ($p<.001$). Neither the main effect of blur ($F_{2,370}=2.30, p>.05$) or interactions involving blur were significant.

For fixation duration, the final reduced model indicated significant main effects of blur level ($F_{2,32}=11.08, p<.001$), viewing condition ($F_{1,85}=25.52, p<.001$) and punch ($F_{2,164}=37.73, p<.001$), as well as significant viewing condition by blur level ($F_{2,162}=7.65, p<.001$) interaction. Bonferroni corrected pairwise comparisons indicated that fixation duration was significantly longer in sequences that were preceded by an arm feint than a foot feint or no feint. In addition, fixation duration in the peripheral condition increased significantly between each level of blur and was different from the central condition at moderate ($p<.01$) and high ($p<.001$) levels of blur. The same pattern of significant main and interaction effects was found for number of fixations. There were more fixations in sequences that were preceded by an arm feint than a foot feint ($p<.05$) or no feint ($p<.001$), and successively fewer fixations in the peripheral condition between each level of blur.

**Discussion and Conclusion:** Using a VR boxing environment with integrated eye movement tracking we studied combat athletes use of deceptive information at the onset of an attack sequence, and whether the clarity of the visual display relative to gaze location impacted upon performance. Participants performed better on the first punch, but not the second and third punch, in a sequence when it was preceded by a foot feint. This indicated that participants were using additional information from the opponent's body movements and situational probabilities to increase performance as the sequence developed. Performance was also better with blur in central vision compared to peripheral vision. Effects of the blur were also evident in the eye gaze data, with participants exhibiting fewer, longer duration fixations in the peripheral condition with each successive increase in the level of blur. No such effects were evident when the blur was applied centrally to a window around the fixation point. Combined, these data from an immersive and adaptive first-person VR setting contribute to our understanding of the information used by combat sport athletes. In addition, they provide support for the finding that participants are to maintain performance when faced with a gaze-contingent blurred visual display [5, 9, 12]). Importantly, extending on previous work, the use of VR provides a controlled environment in which the normal perception-action loop is preserved, and thus offers the means to further examine whether removing high-spatial, low-temporal frequencies, while at the same time conserving low-spatial, high temporal visual information on motion and player position, can facilitate learning and transfer to a real boxing situation.

**Index Terms**—Virtual reality, boxing, blur, sport, perceptual-cognitive skills.

<figure><img src="image_3.png" /></figure>
## ACKNOWLEDGMENTS

This study is supported by the ANR within the framework of the PIA EUR DIGISPORT project (ANR-18-EURE-0022).

## REFERENCES

[1] S. Brault, B. Bideau, R. Kulpa, and C. M. Craig. Detecting deception in movement: the case of the side-step in rugby. *PLoS ONE*, 7(6):e37494, 2012.

[2] C. M. Craig, C. Goulon, E. Berton, G. Rao, L. Fernandez, and R. J. Bootsma. Optic variables used to judge future ball arrival position in expert and novice soccer players. *Atten Percept Psychophys*, 71(3):515–522, Apr. 2009.

[3] M. Kwon, R. Liu, and L. Chien. Compensation for Blur Requires Increase in Field of View and Viewing Time. *PLOS ONE*, 11(9):e0162711, Sept. 2016. doi: 10.1371/journal.pone.0162711

[4] K. Ma, H. Fu, T. Liu, Z. Wang, and D. Tao. Deep Blur Mapping: Exploiting High-Level Semantics by Deep Neural Networks. *IEEE Transactions on Image Processing*, 27(10):5155–5166, Oct. 2018. doi: 10.1109/TIP.2018.2847421

[5] D. L. Mann, B. Abernethy, and D. Farrow. The resilience of natural inter- ceptive actions to refractive blur. *Human Movement Science*, 29(3):386– 400, June 2010. doi: 10.1016/j.humov.2010.02.007

[6] D. L. Mann, B. Abernethy, and D. Farrow. Visual information underpin- ning skilled anticipation: The effect of blur on a coupled and uncoupled in situ anticipatory response. *Attention, Perception & Psychophysics*, 72(5):1317–1326, July 2010. doi: 10.3758/APP.72.5.1317

[7] T. D. Oleskiw, A. Nowack, and A. Pasupathy. Joint coding of shape and blur in area V4. *Nature Communications*, 9(1):466, Dec. 2018. doi: 10. 1038/s41467-017-02438-8

[8] M. Raab, M. Bar-Eli, H. Plessner, and D. Araújo. The past, present and future of research on judgment and decision making in sport. *Psychology of Sport and Exercise*, 42:25–32, May 2019. doi: 10.1016/j.psychsport. 2018.10.004

[9] D. Ryu, B. Abernethy, S. H. Park, and D. L. Mann. The Perception of Deceptive Information Can Be Enhanced by Training That Removes Superficial Visual Information. *Frontiers in Psychology*, 9, Aug. 2018. doi: 10.3389/fpsyg.2018.01132

[10] J. A. Stone, B. W. Strafford, J. S. North, C. Toner, and K. Davids. Ef- fectiveness and efficiency of virtual reality designs to enhance athlete development: an ecological dynamics perspective. *Movement & Sport Sci- ences - Science & Motricité*, (102):51–60, 2018. doi: 10.1051/sm/2018031

[11] H. Strasburger, M. Bach, and S. P. Heinrich. Blur Unblurred—A Mini Tutorial. *i-Perception*, 9(2):204166951876585, Mar. 2018. doi: 10.1177/ 2041669518765850

[12] T. van Biemen, J. Koedijker, P. G. Renden, and D. L. Mann. The Effect of Blurred Perceptual Training on the Decision Making of Skilled Football Referees. *Frontiers in Psychology*, 9, Sept. 2018. doi: 10.3389/fpsyg.2018.01803

[13] A. B. Watson and A. J. Ahumada. Blur clarified: A review and synthesis of blur discrimination. *Journal of Vision*, 11(5):10, Sept. 2011. doi: 10. 1167/11.5.10

* Annabelle Limballe, Alexandre Vu and Richard Kulpa are members of the Univ Rennes, Inria, M2S - EA 7470, F-35000 Rennes, France. richard.kulpa@univ-rennes2.fr

* Simon Bennett is member of School of Sport and Exercise Sciences, Liverpool John Moores University, Tom Reilly Building, Byrom Street, Liverpool, L3 3AF. S.J.Bennett@ljmu.ac.uk

Manuscript received xx xxx. 201x; accepted xx xxx. 201x. Date of Publication xx xxx. 201x; date of current version xx xxx. 201x. For information on obtaining reprints of this article, please send e-mail to: reprints@ieee.org. Digital Object Identifier: xx.xxxx/TVCG.201x.xxxxxxx