Keith Humphreys finds that the Internet is making it harder to avoid disturbing images and videos:
The textbook therapeutic use of exposure under controlled conditions is the treatment of phobias. The patient is trained to relax with a series of muscular and mental exercises and then the feared stimulus (say, a spider) is gradually introduced over a series of sessions.
At first the spider would be introduced just by talking about spiders and webs and the like, then by having a still photo of a spider, followed perhaps by a video of spiders, and then finally an actual spider. The patient retrains him or herself to maintain the relaxed state despite the exposure until the feared object is no longer scary. The patient knows when the sessions are going to happen and that the exposure will be graduated, which fosters the sense of control they need to master their emotional distress.
However, as we interact with the Internet and other media, feared or traumatic images can come at us unpredictably when we are not relaxed and when we feel no sense of control.
The Dish 