Psychologists and psychiatrists agree that there is no way to definitively predict future violent behavior. Yet there are often warning signs, and specialists say people should trust their instincts when they feel threatened by a co-worker, neighbor, or acquaintance.
Psychological studies have shown that perfectly normal college students often have violent ideas and fantasies.
In one recent survey 47 percent of undergraduate students reported having had at least one homicidal fantasy. In another, more than two out of three said they had fantasized about killing someone, and 30 percent of men reported having such imaginings frequently.
‘‘Studies have clearly demonstrated that many more people have homicidal and sexually violent fantasies than act on them,’’ psychiatrists David M. Gellerman and Robert Suddath wrote recently in the Journal of the American Academy of Psychiatry and the Law.
Some specialists have even suggested that violent fantasies may be therapeutic in psychologically healthy people, a mental means of blowing off steam.
Still, there may be hints in a person’s writing to indicate a potential for violence. For example, a writer might reveal his ignorance of social norms in a fictional story that goes too far in breaking taboos, said Gregory K. Moffatt, a psychology professor at Atlanta Christian College.
‘‘You look at the lines that are being crossed and how flagrantly they are being crossed,’’ Moffatt said.
For example? Chopping up the baby sitter is a staple of the horror genre. Chopping up the baby is not.
Cho’s screenplays are bizarre and absurdist, but whether they violate taboos is a matter of interpretation. In one, a boy verbally abuses his stepfather and fantasizes about killing him. When the boy tries to choke the stepfather with a cereal bar, the much bigger man kills him with a single blow.
