Why do we believe things that aren’t true? Sometimes, it’s a matter of the Illusory Truth Effect: Repeated Exposure to (even false) information becomes easy to process in our brains and that easy processing makes it seem true.

Shane Parish discusses this in his latest post, “The Illusory Truth Effect: Why We Believe Fake News, Conspiracy Theories and Propaganda.” Here’s an excerpt:

This is how the illusory truth effect works: we all have a tendency to believe something is true after being exposed to it multiple times. The more times we’ve heard something, the truer it seems. The effect is so powerful that repetition can persuade us to believe information we know is false in the first place. . . . [W]e’re often far outside our circle of competence, reading about topics we don’t have the expertise in to assess accuracy in any meaningful way. This drip-drip of information pollution is not harmless. Like air pollution, it builds up over time and the more we’re exposed to it, the more likely we are to end up picking up false beliefs which are then hard to shift. For instance, a lot of people believe that crime, especially the violent kind, is on an upward trend year by year—in a 2016 study by Pew Research, 57% of Americans believed crime had worsened since 2008. This despite violent crime having actually fallen by nearly a fifth during that time. This false belief may stem from the fact that violent crime receives a disproportional amount of media coverage, giving it wide and repeated exposure. When people are asked to rate the apparent truthfulness of news stories, they score ones they have read multiple times more truthful than those they haven’t.

It seems like the repeated exposure creates a slippery path that runs that information quickly and easily through the brain. William James used this type of metaphor of a “path” in his discussion of memory (this is from “Talks to Teachers, Chapter 12, Memory):

Reflection will show you that there are peculiarities in your memory which would be quite whimsical and unaccountable if we were forced to regard them as the product of a purely spiritual faculty. Were memory such a faculty, granted to us solely for its practical use, we ought to remember easiest whatever we most needed to remember; and frequency of repetition, recency, and the like, would play no part in the matter. That we should best remember frequent things and recent things, and forget things that are ancient or were experienced only once, could only be regarded as an incomprehensible anomaly on such a view. But if we remember because of our associations, and if these are (as the physiological psychologists believe) due to our organized brain-paths, we easily see how the law of recency and repetition should prevail. Paths frequently and recently ploughed are those that lie most open, those which may be expected most easily to lead to results. The laws of our memory, as we find them, therefore are incidents of our associational constitution; and, when we are emancipated from the flesh, it is conceivable that they may no longer continue to obtain.

In his incredible opus, The Principles of Psychology, Williams James elaborates this metaphor, writing about the path along with a marble that rolls down the path. Each time the marble rolls down, it smoothens the path a bit more, making it a more and more fast and direct path.

The psychological law of association of objects thought of through their previous contiguity in thought or experience would thus be an effect, within the mind, of the physical fact that nerve-currents propagate themselves easiest through those tracts of conduction which have been already most in use. Descartes and Locke hit upon this explanation, which modern science has not yet succeeded in improving.
“Custom,” says Locke, “settles habits of thinking in the understanding, as well as of determining in the will, and of motions in the body; all which seem to be but trains of motion in the animal spirits[Pg 564] [by this Locke meant identically what we understand by neural processes] which, once set agoing, continue in the same steps they have been used to, which by often treading are worn into a smooth path, and the motion in it becomes easy and, as it were, natural.”[476]

This is a good metaphor for the process of memory, whether or not the memory is about something real in the world or whether the thing remembered is fake news.”

I like this phrase Shane Parrish uses in his quote: “information pollution.” I’m going add that to my vocabulary.