Mental abuse is often quite hard to track and be recognised as such, because it can be subtle. It can look normal, and its effects can be overlooked. In a society that tends to focus only on physical violence, the importance and severity of mental abuse is not taken into proper consideration. “Gaslighting” is a form of abuse that is exactly this case.
The term derives from a theatre play that was turned into a movie in 1944.
In the story, a husband tries to convince his wife that she is crazy. He makes small changes to their environment and then refusing that there was any change. The most characteristic of the changes made was the dimming of the gas light, which gave the name to the term. Slowly, the wife herself goes into self-doubt, as the data she gathered from her perception were not consistent with what was presented to be the reality.
Perception, combined with reason, is the main way we can construct our understanding of reality.
By allowing another person to alter this perception, our reality is shaken. This is what advertisements do, in a subtler and thus, more manipulative way. They make you doubt your own perception of real needs. In this way they create fictional needs which force you to believe that you are in need of something.