Causal perception is an important cognitive phenomenon, which plays a central role in our understanding of the world. As such, its study is also relevant to interactive graphics systems. In this paper, we introduce a virtual reality system which can elicit causal perception. The system operates by intercepting the consequences of subjects' actions and modifying them to generate new event co-occurrence. This process is based on an explicit representation of action structure, which supports the generation of event co-occurrences on a principled basis. We present results from a user experiment, which confirm a high level of causal perception in subjects having used the system.