"A large study by Jones, Bellet, and McNally found that trigger warnings reinforced the belief on the part of trauma survivors that trauma was central (rather than incidental or peripheral) to their identity."

"The reason that effect may be concerning is that trauma researchers have previously established that a belief that trauma is central to one’s identity predicts more severe P.T.S.D.; Bellet called this 'one of the most well documented relationships in traumatology.' The perverse consequence of trigger warnings, then, may be to harm the people they are intended to protect. In other respects, trigger warnings seem to have less impact than their critics have feared. Some opponents of trigger warnings seem to suppose that they are a way for students to demand that they not encounter ideas that challenge their beliefs.... Trigger-warning studies, however, have revealed that giving trigger warnings does not seem to result in recipients choosing to avoid the material. Instead, the warned individuals tended to forge ahead....  As the scientific consensus on trigger warnings develops further, it’s conceivable that universities might even begin to worry about liability arising from their myriad instructors acting in ways that are known not to help—and possibly to harm—students’ mental health. Perhaps what is called for is a more neutral and humble stance, in which instructors don’t approach pedagogy as if it were an adjunct of psychological care."

From "What If Trigger Warnings Don’t Work?/New psychological research suggests that trigger warnings do not reduce negative reactions to disturbing material—and may even increase them" by Jeannie Suk Gersen (The New Yorker).