One of the goals of much virtual reality (VR) research is to increase realism. In particular, many techniques for locomotion in VR attempt to approximate real-world walking. However, it is not yet fully understood how the design of more realistic locomotion techniques affects user task performance. We performed an experiment to compare a semi-natural locomotion technique (based on the Virtusphere device) with a traditional, non-natural technique (based on a game controller) and a fully natural technique (real walking). We found that the Virtusphere technique was significantly slower and less accurate than both of the other techniques. Based on this result and others in the literature, we speculate that locomotion techniques with moderate interaction fidelity will often have performance inferior to both high-fidelity techniques and well-designed low-fidelity techniques. We argue that our experimental results are an effect of interaction fidelity, and perform an analysis of the fidelity of the three locomotion techniques to support this argument.