Memories aren’t exact records of events. Instead, memories are reconstructed in many different ways after events happen, which means they can be distorted by several factors. These factors include schemas, source amnesia, the misinformation effect, the hindsight bias, the overconfidence effect, and confabulation.
A schema is a mental model of an object or event that includes knowledge as well as beliefs and expectations. Schemas can distort memory.
Example: Suppose a high school junior visits her sister’s college dorm room for the first time. She’s never been to a dorm before, but she’s seen dorms in movies, read about them, and heard her friends talking about them. When she describes the room to another friend after the visit, she comments on how many clothes her sister had and how many huge books were on her sister’s desk. In reality, the books were hidden under the bed, not out in the open. The clothes were something she actually saw, while the books were part of her dorm-room schema.
Another reason for distorted memories is that people often don’t accurately remember the origin of information.
Example: After witnessing a car crash on the freeway, Sam later tells friends many details about what he saw. It turns out, however, that there is no way he could have actually seen some of the details he described and that he is, in fact, just reporting details he heard on TV about the accident. He isn’t deliberately lying. He just may not be able to remember where all the different pieces of information came from.
This inaccurate recall of the origin of information is called source amnesia, source misattribution, or source monitoring error.