 The mere exposure effect is a psychological phenomenon by which we tend to like things merely because we are exposed to them. So simply exposing you to a random thing repeatedly makes you like it, and the same goes for pop songs, products and people, with the exception of those we dislike initially, seeing them more often can make us dislike them further. When we plot the mere exposure effect on a graph with preferences on one axis and repetitions on the other, we will see that it takes about 15 repeats for the effect to reach its full potential. If the exposure is too excessive, people get annoyed, and if they didn't like the thing initially, repeating it can make it worse. There are two main explanations for the phenomenon. The first is certainty. We favour what's familiar. Our minds naturally learn to be careful around new things that could potentially harm us, which also means that if we see something repeatedly without bad consequences, we are led to believe it is safe. The second is perceptual fluency. We are also hardwired to prefer simple things that take little mental load. Hard cognitive tasks, like figuring out something new, take lots of attention and time, which is why we try to avoid them. Known for discovering the effect were psychologist Robert Zients, who had noticed that organisms exposed to something new experience fear. Each subsequent exposure to that new thing causes less fear and more interest, and with more exposure, the observer begins to react fondly to the once novel stimulus. Zients then tested how subjects responded to specific symbols, such as Chinese ideograms. Subjects were shown various characters a different number of times, and were then asked which ones they liked. Those who were shown certain symbols the most also rated them as most favourable, but science found something even more spectacular. Using a tachistoscope and a group of people, he exposed each person to a series of random shapes that changed so quickly that it was impossible to discern that some were repeated. When the people were later asked which shapes they found most pleasing, they reliably chose those to which they had been exposed the most often, even though they had no conscious awareness of that. The results validated one of science's hypotheses. Changes in preferences induced by repeated exposures depend not on any prior subjective and conscious evaluations of attributes of the stimulus, but rather on results from the objective history of exposures alone. In 1968, advertisers and marketing executives were able to read science's publication. Some were happy to learn that the effect on the brain can be stronger if exposure comes with other pleasant stimuli. The psychologists continued to study the human psyche. Later, he famously noted, For most decisions, it is extremely difficult to demonstrate that there has actually been any prior cognitive process whatsoever. It isn't that the decisions people make are irrational, it's that the process by which decisions are made is utterly unlike the step by step rational process that might be used to solve, say, a math problem. Decisions are typically made in the unconscious mind by means of some unknown process. Now tell us, which of these shapes do you like the most? And were you aware that you were exposed to one more than the others? Also, tell us what you think about ads. If mere exposure to the makes us like things we otherwise wouldn't, should billboards be banned from the public domain? The artist Banksy said, Any advert in a public space that gives you no choice whether you see it or not is yours. But is he right? If you like how we explain complicated ideas in simple cartoon animation, you can support us. Visit Patreon.com slash Sprouts. Just visit us, learn how it works and what's in it for you. We hope to see you there. And if you are a parent or educator, check out our website, Sproutschools.com. There you can find this and other video lessons, additional resources and classroom activities. If you found this helpful, check out our other videos and subscribe. If you want to support our work, join us on Patreon.com slash Sprouts. For more information and additional content, visit Sproutschools.com.