A virtual reality bus ride as an ecologically valid assessment of balance: a feasibility study

Balance disorders can have substantial adverse implications on the performance of daily activities and lead to an increased risk of falls, which often have severe negative consequences for older adults. Quantitative assessment through computerized force plate-based posturography enables objective assessment of postural control but could not successfully represent specific abilities required during daily activities. The use of virtual reality (VR) could improve the representative design of functional activities and increase the ecological validity of posturographic tests, which would enhance the transferability of results to the real world. In this work, we investigate the feasibility of a simulated bus ride experienced in a surround-screen VR system to assess balance with increased ecological validity. Participants were first evaluated with a posturography test and then with the VR-based bus ride test, while the reactions of their centre of pressure were registered. Lastly, participants provided self-reported measures of the elicited sense of presence during the test. A total of 16 healthy young adults completed the study. Results showed that the simulation could elicit significant medial-lateral excursions of the centre of pressure in response to variations in the optical flow. Furthermore, these responses' amplitude negatively correlated with the participants' posturography excursions when fixating a target. Although the sense of presence was moderate, likely due to the passive nature of the test, the results support the feasibility of our proposed paradigm, based in the context of a meaningful daily living activity, in assessing balance control components.