As we have already discussed, experiences from our interaction with the world (what I usually call external stimuli) give us hints that a potential discomfort (or pleasure, but for this post I’ll be focusing on negative experiences) are upcoming…
In this case a Driving Pocket (DP) is activated, which is our mind’s method of focusing our attention into resolving this problem before it even occurs, i.e. we’re trying to alter the future towards our advantage.
According to how big the discomfort is expected to be, the DPs are correspondingly large and will also dissipate more slowly. This is an evolutionary advantage, because it allows us to put our energy where it counts more (in the big DPs) and because the big DPs need time to dissipate, it secures us enough dedication of our most precious resource, our brain’s problem-solving attention mechanism, to maximize the probability of solving the problem.
In order for the problem to go away, we have 3 options:
1) either let it dissipate with time… We already discussed this, time heals all wounds and all that. Actually this is not a solution.
2) or we solve it by connect this disturbing issue with a comforting thought that reduces our worry. E.g. "oh yes, I remember now that I turned off the water heater before leaving the house"
3) or we solve it by altering our environment to stop the disturbance. E.g. I get up and turn off this annoying music on the radio.

The issue with these options is that sometimes the 2 latter solutions are not always easy/possible to find, especially in traumatic experiences which create very big/extensive DPs. I will go to the extremes, to illustrate the point: so when a child was molested, when a loved one is dead, when somebody had a disfiguring accident… it’s not really easy to find solutions for that. There are not many comforting thoughts strong enough to overpower the big DPs that is troubling the mind of the individual. And there are no actions that can simply bring back to life a relative of yours. I believe you get the point.

This causes the following effect in our mind: the DP is created, it tries & tries again to find a solution (with a thought or an action) but it fails. In the end it will dissipate for the time being, but it will not have been resolved.
And now comes the other feature of our brain mechanism: paths that have already been activated/traversed are much easier in the near future to be activated again. And DPs that have not been resolved will also be reactivated as soon as the related stimuli/patterns/thoughts/experiences come to mind.
In plain words, because we left unresolved this dangling issue at the corner of our mind, the next time we see/hear/experience anything remotely similar to this, the brain pathways towards this will be reactivated and the DP will be turned on again.
Thus the brain enters into a new attempt to resolve them problem. Which again evolutionary might be the right thing to do because you might have the opportunity to tackle it in a new environment, with a potentiall different mental state and fresh ideas. But when we’re talking about those big, negatively influential experiences, it’s quite probable that this new effort (and many other similar efforts in the future) will not prove fruitful. Even worse, because you reactivated this area in the brain, it’s still very easy to be activated again and again. It’s a vicious circle, that can really suck you in and drown you into depression.
The theoretical solution is simple and is based on the alternatives we described above: either change your environment to undo the situation (option 3), or try to connect these bad experiences with non-disturbing thoughts and accept them (option 2), or simply try to avoid any environmental stimuli that will remind you of the issue (option 1). So in theory it’s simple, but in reality the solution is never simple…

On a similar note, this mechanism is of course universal and applicable even for non-big one-off negative experiences, but of smaller and repetitive ones. In other words, even if I don’t experience a big, negative life-altering event, I may have a constant annoyance that disturbs me again and again.
For the same reasons, if my brain is not able to find a solution to it, it gets reactivated again and again, growing bigger and is able to leave a similar mark after a lot of time & repetitions.

The simple advice out of all this is: make sure you solve your issues! Don’t let them dissipate with time, because if the root cause is not dealt with, they will resurface with a spite.
In the end, the brain is like a big minefield. Spread thoughout its expanse of patterns and thoughts are "planted" smaller or bigger bombs, i.e. DPs that were not solved and repressed and will trigger an emotional reaction when stepped upon/activated.

When you talk to people about various topics, you might say specific words that will "awaken" those dormant DPs and then you will see their reaction. You need to traverse this minefield with care, being aware of how it’s built and what its effects are.
People who have experienced many negative experiences (DPs) and did not resolve them properly with have a minefield with many mines. You might say "they have issues, they are damaged". Others might have less. Remember, you always have the opportunity to defuse one mine, when you come across it. Either in yourself, or in the others; whatever the case you will do us all a favor 🙂