Wolter, MarcArmbruester, ClaudiaValvoda, Jakob T.Kuhlen, TorstenBernd Froehlich and Roland Blach and Robert van Liere2014-01-272014-01-272007978-3-905674-02-61727-530Xhttps://doi.org/10.2312/EGVE/IPT_EGVE2007/025-032Virtual Reality (VR) has become a useful tool in psychological therapy, rehabilitation, and basic research. It provides the therapist or scientist with high ecological validity and complete control over multimodal stimuli and the virtual environment. To build lifelike virtual environments, commercial software or game engines are often used. On the other hand, many psychological experiments require an accurate timing of presented stimuli and user reactions, which is not easily obtained by modern hard- and software systems. In this work, we present a VR software for psychological experiments which combines modern computer graphics and Virtual Reality techniques with accurate stimulus and event control. We describe the system features and possibilities for VRbased experiment generation and propose approaches for precise stimulus and event timing. These approaches are evaluated for achievable accuracy in stimulus control and performance monitoring within typical virtual environments.Categories and Subject Descriptors (according to ACM CCS): C.4 [Performance of Systems]: Measurement Techniques, I.3.7 [Computer Graphics]: Virtual Reality, J.4 [Social and Behavioral Science]: Psychology