Book excerpt: The Encyclopedia of Psychological Trauma is the only authoritative reference on the scientific evidence, clinical practice guidelines, and social issues addressed within the field of trauma and posttraumatic stress disorder. Edited by the leading experts in the field, you will turn to this definitive reference work again and again for complete coverage of psychological trauma, PTSD, evidence-based and standard treatments, as well as controversial topics including EMDR, virtual reality therapy, and much more.