Psychologists have investigated whether it is possible to prevent the development of flashbacks after a traumatic event. Researcher Emily Holmes and her colleagues have suggested that, since flashbacks are often powerful visual images, it may be possible to reduce the severity by “distracting” the visual system. To test this idea out, Holmes and her colleagues conducted an experiment in which participants watched a potentially traumatizing video. Afterwards, some participants played Tetris, and others did not. The researchers found that participants who played Tetris only had about half as many flashbacks as the participants who didn’t. In other words, it appears that a neutral activity such as Tetris kept the visual systems in the participants’ brains occupied, making flashback images less likely to occur. In another paper by Dr. Holmes’ research team, researchers asked emergency room patients who had experienced a traumatic event to participate in a similar study. Some participants played Tetris while others did not, and the researchers found that participants who played Tetris had fewer intrusive memories of their traumatic event over the next week. More broadly, researchers have found that psychotherapy and medication can reduce the severity of PTSD symptoms, including flashbacks. One type of therapy, Prolonged Exposure, involves discussing the traumatic event in a safe, therapeutic setting. Another therapeutic technique, Cognitive Processing Therapy, involves working with a therapist to change one’s beliefs about the traumatic event. Researchers have found that both types of therapy are able to lessen the severity of PTSD symptoms.