"A problem with the human mind - your human mind - is that it's a horrific kludge that will fail when you most need it not to. The Ugh Field failure mode is one of those really annoying failures. The idea is simple: if a person receives constant negative conditioning via unhappy thoughts whenever their mind goes into a certain zone of thought, they will begin to develop a psychological flinch mechanism around the thought. The "Unhappy Thing" - the source of negative thoughts - is typically some part of your model of the world that relates to bad things being likely to happen to you."