Heuristics are mental shortcuts we take to survive. Given the sheer number of decisions and choices the average person has to make on any given day, our brain would overheat if every one of them would get the same consideration. Therefore, our brain goes on autopilot, whenever possible. The brain bases its choices on earlier experiences. As life becomes more hectic, the number of decisions delegated to the automatic pilot increases.
Yet, this process is not always flawless. Particularly when a past event was traumatic in one way or another, heuristics can cloud our judgment and lead us astray.