Illustration of trial flow.

The flow chart visualises how the program progresses through a trial of the triangle completion task of our showcase study. Trial flow is managed by the VNT trial state machine module, which in turn calls up functions from the other VNT modules, as well as from the UXF framework. This visualisation reveals the complexity of interconnected components that need to be managed when designing VR experiments, even when only considering a relatively simple design like the triangle completion task. A state machine, as we have provided with the VNT and used for the showcase study, helps make this complexity manageable by packaging the different phases of the experimental trial (Displacement, Homing, etc.) and clearly defining the logic that governs the transitions between the states (i.e. phases) of the experiment. Rounded boxes summarise the tasks managed within each state. Light green tasks are handled by a VNT module or the UXF, while grey tasks are currently handled in a project-specific manner, but could be included in the VNT as part of the ongoing toolbox development.