Extensive training is crucial but challenging in certain areas such as explosive ordnance disposal. Past conflicts have shown that not only military personal but also civilians have to learn how to disarm unexploded ordnance. The preparation for dangerous situations is difficult and limited in the real world. Extended reality (XR) offers new possibilities to enhance the training of explosive ordnance disposal experts due to its immersive capabilities. This paper presents a comparative study (n = 75) of three distinct training methods: 1) Real-world (Real)-Training with a tangible replica object, 2) Virtual Reality (VR)-Training with a non-see-through Head-Mounted-Display (HMD), and 3) Mixed Reality (MR)-Training in a Cave Automatic Virtual Environment (CAVE). All training methods are collaborative, i.e., an instructor teaches the training content to a participant in the real or virtual world. We evaluate the suitability of these approaches in terms of usability, cognitive workload, training motivation, and training success. Our results indicate that the virtual methods, VR-Training and MR-Training, provide significantly superior results in the evaluated aspects compared to the real-world training. These results can also be applied to other collaborative training methods, as the training concept of this use case was non-specific. Therefore, these virtual technologies can increase the safety of explosive ordnance disposal personnel, and we recommend establishing this in future training.
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