23 | The temporal development of motion sickness symptoms and general feelings of sickness

Background: To better understand and mitigate motion sickness, it is essential to be able to quantify its progression unambiguously. Self-report rating scales either focus on measuring specific symptoms or on general feelings of unpleasantness or sickness. Previous research has suggested that motion sickness symptoms generally manifest in a fixed order, with non-nausea symptoms preceding nausea. In contrast, unpleasantness was shown to increase non-monotonically, with a temporary reduction at the transition from non-nausea symptoms to nausea. However, other authors have suggested that unpleasantness does increase monotonically with symptom progression. How can we reconcile these conflicting findings? The previous studies used a research design in which symptoms and unpleasantness were measured separately (either semantically or retrospectively). Here we measured both within one motion exposure to answer the following two research questions: 1) how does sickness develop during symptom progression and 2) do non-nausea and nausea symptoms develop in a fixed order? Materials and Methods: Participants were exposed to the same provocative motion stimulus in two different sessions on separate days. In one session, participants alternately rated their symptoms using the Motion Illness Symptoms Classification scale (MISC) and their sickness using the Fast Motion Sickness scale (FMS). In the other session, participants rated the extent of non-nausea and nausea symptoms they experienced on separate scales, in alteration with FMS ratings. Results: Data collection is still in progress. The results will provide insights into the progression of motion sickness symptoms over time and how they relate to the level of experienced sickness.