We are all familiar with the idea of triggers. Things, events, places that take us back to the site, sounds and feelings of the trauma we suffered. These triggers are usually something more or less directly related to the trauma its self. Something present at the time of the traumas such as a sound, smell or physical sensations. Sometimes a visual queue will act as a trigger but again these tend to be more or less directly related to the underlying trauma.
Because of this direct, and often visceral connection to the deep levels of our sub conscious we are often able to identify the trigger and its relationship to the trauma itself.
A good example being a smell that was present when we were abused triggering memories, and an emotional response, when we smell it in later life.