http://www.ncbi.nlm.nih.gov/pubmed/20712501
Efficacy of VR exposure therapy in anxiety disorders , in cluding PTSD:
http://en.wikipedia.org/wiki/Virtual_reality_therapy#Efficac...
Exposure therapy probably works via habituation or conditioning.
http://www.nelsonbinggeli.net/NB/CBT-Exposure.html
The knowledge on how military training works is found on dave grossmans's book : "on killing".