So many things missing from this. They analyzed a bunch of suspect studies to try to come up with something not suspect by throwing out "bias" and "flaws." Such as? Plus, what counts as an "event?"
This sounds to me like cherry picking results. I have feelings that something bad is going to happen right before something does. I have these same feelings right before nothing bad happens. They're just feelings you have because of stress or anxiety or whatever. If I were in a situation where I was shown a bunch of photos I'd eventually realize that some of them were going to be scary after one or two and I'd be anxious about the whole process. That right there doesn't sound like a very good way of controlling the variables in a study.