Effect of delay on dynamic targets tracking performance and behavior in virtual environment

We analyze the impact of the delay between the sensors and the visualization on the performance at a catching task in virtual environment. Testers have been asked to interact with a virtual environment displayed on a 2D screen in front of them, catching, with the virtual hand, virtual balls falling from the top of the screen. Two thresholds have been inferred: a behavioral threshold delay beyond which the behavioral organization is sensibly affected and a performance threshold delay beyond which task performance begins to worsen. We found a drop in performance when the total delay is over 70-80 ms, yet without significant changes in the organization of successful catches. Although the presence of a threshold on behavior is still to be further investigated, these two thresholds give a practical indication for the design and the validation of virtual reality based training systems. This is especially important in the context of training human skills in virtual environment: in particular to assess the quality of a training platform simulating the three ball cascade juggling pattern.