Ms. Laperal also reached some unsettling conclusions in her interviews with content moderators. She said they were likely to become depressed or angry, have trouble forming relationships and suffer from decreased sexual appetites. Small percentages said they had reacted to unpleasant images by vomiting or crying.
“The images interfere with their thinking processes. It messes up the way you react to your partner,” Ms. Laperal said.
Sounds like psychological trauma to me. However, what these people are doing is sitting at a desk all day and reviewing the content we all upload to various sites. Many big tech companies outsource this work. Google keeps it in house (reviewing videos for youtube) but monitors employees closely for signs of stress and doesn't let them do it for more than a year.
Unfortunately, this isn't a problem that's easy to solve. While computer vision can recognize some objectionable content, some of it is just too subtle.
Read more here:
http://www.nytimes.com/2010/07/19/technology/19screen.html