Difference & Fear
We are all conditioned by the culture that we live in. The media has a great influence on how people are viewed. Using difference, often a difference perceived as negative. Using a blemish--a disability--physical, cognitive or emotional has become a shorthand for bad, evil, and undesirable. Some of our cultural perceptions have a long history. Disabilities that have an emotional element, especially those that cause people to act in unpredictable ways such as schizophrenia still cause unease in people. In other times such individuals were cursed or possessed. Even knowing that there is a chemical cause sometimes doesn't offset a constant reinforcement of this nature.