The Illusionary truth effect is a cognitive bias in which people become more likely to believe something when they've heard it multiple times regardless of its truthfulness. It happens as a result of the brain's tendency to process things more effectively when they are familiar. When a statement is repeated multiple times it becomes easier for the brain to take on board and make sense of. The best examples of the illusionary truth effect can be seen in political campaigns. The danger of the illusionary effect is that it can create false memories leading people to believe that they have experienced an event or heard something before when in reality they actually haven't.