There are some findings I have recently been reading about that show our brains protect us by processing negative events either worse than they really are or not as bad as they really are, depending on the situation.
In a study that looked at tasks like listening to an annoying noise or doing an irritating activity, if we think the negative event will not happen again, we remember it as not as bad as it really was (reducing the trauma of the memory). But if we think it will happen again, we remember it worse than it really was so that the next time the negative event occurs, it feels not as bad in comparison. But the memory bias didn’t happen if the person didn’t have the time or the attention to think about whether or not the negative event would happen again.
Another study looked at a bitter drink. In this study, when a person thought they would have to drink it 20 times, their brain applied some top down bias by making it taste not as bad as it really is while they were drinking it. So memory protects us one way and top-down processing protects us another way.
A third study looked at how students thought they did on an exam. Right afterwards, they were optimistic about how they did. But just before receiving their grades, they were much more pessimistic “just in case.” Their brains mentally protected them from potential bad news by lowering their expectations.
The authors called this “bracing” because it’s like physically bracing yourself from a painful experience. Like when the doctor is going to stick you with a needle and says “This will only hurt for a second.”
None of this is purposeful, it's just something our brains have evolved to do. Sometimes it is fascinating how smart our brains can be when we are not using them.