If one of them finds clowns as distressing as another finds, say, reminders of gunfire-- doesn't that mean that pretty much everything needs a trigger warning?
And before someone starts laughing that one off, it's not at all implausible for a 10yo to be sexually assaulted by a relative at a Halloween party who dressed as a clown. A clown could be just as triggering for a combat vet, who experiences a PTSD event in an urban war zone, and in the midst of carnage sees something incongruous with the surroundings, which draws his attention, and it's this image which is burned into his memory and forever associated with the horrors he has witnessed... a child's clown doll.
But I think the teacher in the NYT piece answered it as well as anyone reasonably could:
As teachers, we can’t foresee every instance of potentially triggering material; some triggers are unpredictable. But others are easy enough to anticipate, specifically, depictions or discussions of the very kinds of experiences that often result in post-traumatic stress and even, for some, a clinical disorder.
and:
Of course, all this still leaves the questions of how and when to give trigger warnings, and where to draw the line to avoid their overuse. There is no formula for this, just as there is no formula for designing classes, for successful teaching and meaningful communication with students.
The reality is that most sexual assaults and domestic violence go unreported, and digging too deeply could be considered a violation of student privacy, so apart from taking reasonable precautions like the teacher is doing, the only way to discover most PTSD triggers is after the fact.
