Many psychologists and other scientists will use schemas to describe the organization of knowledge about human cognition. Schemas are typical ideas or mental images of how something or someone should look like or act or how an event should occur.

Schemas for objects.

A schema does not have to actually exist in physical reality. For example, one's schema of a dog may be a four-legged, medium-sized dog with brown fur. Yet, even if you went to an animal shelter or pet store, you might find it hard to find an actual dog that would match your image.

Certain objects within a category will fit the schema better than others. For example, a robin seems like a much more typical bird than does a penguin.

Schemas for events.

What did you eat for lunch exactly one week ago? ... Did you eat all your food? ... What time was it? ... Where were you? ... With whom did you eat? ... About what did you converse?

Your answers to these questions may be a combination of episodic and semantic memory.

In your semantic memory, you develop schemas, general knowledge about an object or event. Schemas are generated through experiences (Cohen, 1989, as cited in Matlin, 1998). "Eating lunch," is a likely schema that you may rely upon to provide information to answer the questions above.
Sometimes these schemas cause us to remember something that never really happened, because they fit in well with our schema (Neisser, 1988, as cited in Matlin, 1998). If something happens repeatedly, the events may be blurred together and indistinguishable (Neisser, 1988, as cited in Matlin, 1998).

Schemas are affected by memory.

Schemas are developed by our blending of memories of similar experiences (Yount, p. 86). As you observe or learn more about the category for a schema, you may come across something different from your current schema. Your brain must decide how to react to this conflict in observation and expectation. You may consciously adjust your schema so that it fits your experience. In some cases, you may adjust your mindset without even realizing

Memory is affected by schemas.

If you already have an expectation about a person or an event, your memory of that person or event will be shaped based on your preexisting schema. For example, if you have already fit into your schema that urban teenage males are rude and you meet a nice urban male teen, your memory of him may be affected. If you were surprised with his politeness, you may remember him as even more polite than he is. Or, you may not even notice how polite he was because you were expecting him to be rude, and so you remember him as the typical urban teen you had previously imagined in your mind.

A real life example of a traditional memory being shaped by one's schema is the memory of the U.S. Civil War. Civil War Memory

Memories of the United States Civil War (also called the War Between the States, or any war for that matter, can differ greatly on each side. This picture is from a Civil War memorial site. On either side of the statue, flies a flag representing the opposing sides: the Union, or United States government represented by the flag on the left, the Confederacy, or the South, by the flag on the right, both full mast. The statue is in memory of all the soldiers from that State who fought on obth sides in the Civil War. This is from Heidelberg.