According to the free dictionary schema is a "diagrammatic representation; an outline or model" and in psychological approach, it is "a pattern imposed on complex reality or experience to assist in explaining it, mediate perception, or guide response."
So, schema is a mental structure that can be applied in everything in our real life, as a simplified knowledge about ourselves, others and every other thing.
This mental perception could affect every aspect of our life; it would direct our thought and accordingly our action in encountering any phenomena. In fact, schemas in our minds are filters that everything goes through them and then we decide how to react. The ranges of schema contain everything, however, Changing Minds. Org has categorized some types of it like this:
"Social schemas are about general social knowledge.
Person schemas are about individual people.
Idealized person schemas are called prototypes. The word is also used for any generalized schema.
Self-schemas are about oneself. We also hold idealized or projected selves, or possible selves.
Role schemas are about proper behaviors in given situations.
Event schemas (or scripts) are about what happens in specific situations."
[1]As a conclusion, we can say if you have a positive conception about any subject it will encode in your mind as a positive and you will remember it with its positive aspect. If someone loves sea, definitely he has had a favorable image about the sea, but if someone is afraid of sea, he probably has an experience about drowning one of his beloved one in the sea.
This is applicable to any other mental representation. I have a personal experience. In 1981, my brother came to Iran, after nearly 17 years living in the U.S. Then, as the war with Iraq was recently finished, the representation of Iran was a poor and miserable country, which is full of chaos and violence. When my brother called his wife after a couple of days and said he had gone shopping and had bought some Chiquita banana, his wife, a native American, had amazingly asked if there was any Chiquita banana in Iran? In fact, her social schema about Iran according to information had gathered from media was a starving third world country.
There are the same false schemas in Iran against the United States. Some of people obsessed with the anti America schema may think the people of this country are occupied with the animosity about Iran, while if they establish personal contact, they will understand those imaginary enemies are human beings like themselves, with kindness, affection, respect and open mindedness toward others. Therefore, to be ready to change a schema when one finds it is not true, needs braveness.
[1] .
http://changingminds.org/explanations/theories/schema.htm