The chronic exposure to stress affects organisms that deal with daily activities and it also interferes with one's coping mechanisms. Once the HPA axis is activated, it triggers an increase in glucocorticoids. Once these hormones cross the blood–brain barrier, they interact with other neurotransmitters and change the brain's chemistry as well as structure. The process of habituation is important to consider because it is a prevalent variable in the phenomenon of psychic numbing. The constant exposure a society or individual has to a prolonged and sustained aversive stimuli, the emotional magnitude that the stimuli has decreases greatly over time to where it becomes unnoticeable to those who have been surrounded by it for a long period of time. This type of response is seen in Vietnam veterans and rape victims who suffer from PTSD. Additionally, studies describe the importance of the rACC and the cingulate cortex for comprehension and the feeling of a painful stimulus. Taiwanese and American researchers recorded brain-wave readings from participants as the researchers observed body parts pricked with a pin, or dabbed with a Q-tip. Half of the subjects were physicians and the other half was a control group. The control group showed clear differences in his or her reactions to the pin-prick in comparison to the Q-tip. The physicians, who previously had experience managing sickness and pain, did not. The authors of the study theorized that the physicians unconsciously numbed their reaction to the pain of the pin-prick due to his or her profession. This may be a beneficial result because physicians need to block out the pain response and use more cognitive resources necessary for being of assistance in a time of need. This further suggests the individual differences people have in regards to psychic numbing and the deviation away from more tragic accounts of rape and PTSD. This type of desensitization is not independent of the participant's lives, instead it is a result of years of experience woven into his or her daily lives, resulting in a numbed response. Figures of areas of the control group's brains showed activation in the rACC, and the physician's brains did not, suggesting there was already habituation. Conceptualizations The original view of psychic numbing dealt with human extinction and the mass response to potentially life-threatening scenarios. Lifton argued the worry for these events was low and therefore generated an equally low probability of occurrence point of view.