Virtual Reality (VR) applications commonly use the illusion of self-motion (vection) to simulate experiences such as running, driving, or flying. However, this can lead to cybersickness, which diminishes the experience of users, and can even lead to disengagement with this platform. In this paper we present a study in which we show that users performing a cognitive task while experiencing a VR rollercoaster reported reduced symptoms of cybersickness. Furthermore, we collected and analysed brain activity data from our participants during their experience using functional near infra-red spectroscopy (fNIRS): preliminary analysis suggests the possibility that this technology may be able to detect the experience of cybersickness. Together, these results can assist the creators of VR experiences, both through mitigation of cybersickness in the design process, and by better understanding the experiences of their users.