Just a Hunch

Hunches are related to the development of intuition. Look at it as a feeling based on intuition rather than known facts: acting on a hunch. This does not mean that your actually basing this hunch on no facts at all. The key word is known facts but could better be expressed as facts in storage. Hunches and Intuition are based on a combination of knowledge and experience. When a hunch triggers your spidey senses it means something previously known and experienced but cannot rise up to the most conscious level has triggered the spidey sense or the hunch. 

Hunches in martial arts or self defense are those experiences and knowledge trained and practiced to a degree that the hunch arrives and you act. Hunches also provide you the means to avoid circumstances that could result in violence. The ability to have hunches is to use intuition and analysis to act according to the stimuli in the moment. Calling this a hunch is sometimes limiting without a greater understanding of how all this works.

It is not some mystic sixth sense technique but rather the acquisition of knowledge and experience that practiced and trained diligently result in reprogramming of the lizard brain to act appropriately in sometimes volatile situations.