Psychological trauma can change, destroy and create many negative impacts in a person's life. The primary definition of psychological trauma is the result of a unique individual experience of an unusual event that invaded a person's sense of security, causing them to feel helpless and at risk of a dangerous situation, and their ability to assimilate his emotional experience. is overwhelmed by certain situations. (Lawrence Robinson, 2011) Much more severe psychological trauma can lead, in certain circumstances, to post-traumatic stress disorder (PSTD). Post-traumatic stress disorder (PSTD) is an anxiety disorder that some people may change after seeing or experiencing a dangerous incident or after being exposed to any event that causes psychological trauma. (National Institute of Mental Health (NIMH), 2009). For example, when a person is in danger, he certainly feels fear. These fears eventually trigger changes in the body to prepare to protect itself against or escape danger. But for someone who suffers from post-traumatic stress disorder, their reaction is no longer the same as that of a normal, that is to say damaged, person. These people usually feel stressed or fearful even when they are safe and already escaping danger. Several factors cause psychological trauma in an individual. They are classified into two categories, the difference between a single blow and repeated trauma, with emphasis on whether it is natural or man-made trauma. These two categories cover almost all the factors that cause psychological trauma in an individual and we will explain them in detail in the following paragraphs. As additional information, two people undergoing similar testing...... middle of paper ......University of South Carolina: SC. Department of Psychiatry and Behavioral Sciences. Lawrence Robinson, MS (December 2011). HELPGUIDE.ORG. Excerpted from Healing Emotional and Psychological Trauma: http://helpguide.org/mental/emotional_psychological_trauma.htm(nd). Retrieved from Ten Top Technological Disasters: http://sct11.weebly.com/uploads/5/9/3/7/593742/lukes_top_ten_technological_disasters.pdf Perry, DB (1994). Neurobiological sequelae of childhood trauma: PTSD in children. Catecholamine function in posttraumatic stress disorder: emerging concepts. National Institute of Mental Health (NIMH), UD (January 21, 2009). Post-traumatic stress disorder (PTSD). Excerpted from What is Post-Traumatic Stress Disorder, or PTSD? : http://www.nimh.nih.gov/health/publications/post-traumatic-stress-disorder-ptsd/what-is-post-traumatic-stress-disorder-ou-ptsd.shtml