This Lecture Makes Me Sick: On Confounding Factors Influencing the Simulator Sickness Questionnaire (SSQ)

The Simulator Sickness Questionnaire (SSQ) has become a standard tool for quantifying the severity and distribution of discomfort symptoms in virtual reality (VR) research. Despite its straightforward administration, the use of the SSQ also comes with significant challenges, including response subjectivity, strict threshold values based on a military reference population, and confounding factors influencing the results. To demonstrate the adverse interplay of these issues, we asked three cohorts of students to fill in a SSQ after having attended a 90-minute lecture of our teaching program. Although students were not exposed to any form of VR experience, the resulting SSQ scores were indistinguishable from VR studies and extended far beyond the originally defined threshold of a "bad simulator", with 88.1% of TS scores being larger and 25.4% even exceeding thrice this value. We compare our results to alternative scoring systems of the SSQ proposed in the literature and suggest implications for future experimental designs involving the quantification of sickness symptoms. In summary, our results motivate to exert caution when interpreting the results of the SSQ in the context of a VR study; participants might just have attended a lecture prior to the experiment.