Our everyday decision making is based on aggregate statistics, whether we realize we are doing that or not. Basically, the more something happens, the more we expect it to happen in the future. There are influences on that relationship that creates biases in different kinds of situations, but experience is generally the largest impact on our decisions.
The problem with this is that our brain did not evolve to separate factual experience from fiction (TV, movies, even dreams). This makes sense because 99% of our evolution occurred before there was TV and even campfire stories were mostly true throughout most of human history. So when we see things on TV or movies, they have just as much of an impact on our future decisions as real life does. It’s even worse because we don’t realize this is happening so we can’t stop it.
TV shows like CSI have increased juries’ expectations for what forensic science should be able to do. They now hold real CSIs to a higher standard than is really possible. Defendants are more likely to be found not guilty or to get lighter sentences because of a TV show.
A new study by Levine, to be published in the journal Communication Research illustrates an interesting example of this. The show Lie to Me has created a new effect. People who watch this show are more likely to think people are lying, but actually less able to tell when people are lying. Oops.