At the recent PRESENCE summer school in Dubrovnic we had a very interesting talk by Jeremy Bailenson, director of of Stanford's Virtual Human Interaction Lab which threw up some very powerful ideas on presence and interaction and how these can be manipulated in VR. This is interesting in itself but I think it highlights just how "hackable" we are. This has some serious applications in terms of marketing and potentialy politics if one of Jeremy's experiments were to be somehow implemented (http://vhil.stanford.edu/pubs/2005/identity-capture.html). But it also offers insight into the cognitive process and can help us learn a lot about how we work. If we can interupt or manipulate processes that we are normally not aware of then we can learn something about what that process does and maybe why it is neccessary.