We tend to like what we've seen before
Think of a song you didn't care for the first time, which grew on you after you had heard it a few more times. The song didn't change. You had just heard it more.
Psychologists call this the mere exposure effect: people tend to develop a liking for things merely because they are familiar with them. Gustav Fechner studied it as early as 1876, but the name and the best-known experiments belong to Robert Zajonc, a Polish-born social psychologist who taught at the University of Michigan for nearly four decades.
In 1968 Zajonc published a long paper, Attitudinal effects of mere exposure, arguing that repeated exposure to something is enough by itself to warm our attitude toward it. No reward, no argument, no persuasion. Just repetition.
His experiments, and many that followed, used things people had no opinion about to begin with: nonsense words, unfamiliar written characters, drawings, photographs. Some were shown many times, others rarely or not at all. In one well-known version, people who couldn't read the characters were told each one stood for an adjective and were asked to guess whether its meaning was good or bad. The characters they had seen before were consistently judged more positive.
Liking without remembering
Later studies flashed images too briefly for people to notice them. Asked whether they had seen an image, people did no better than chance, yet they still leaned toward the ones that had been shown. Zajonc took this as evidence that feelings can form before, and apart from, conscious thought, an idea he set out in a 1980 paper with a memorable title: Feeling and thinking: preferences need no inferences.
That 1989 review, by Bornstein, found the effect strongest for unfamiliar things shown briefly, and found that it usually peaked within 10 to 20 exposures. The effect was weaker in children, and weaker for drawings and paintings than for other kinds of material.
It has limits. With enough repetition, liking can turn back down, like a song played once too often. And familiarity doesn't soften everything. In one study, more exposure to people whom participants already disliked made them dislike those people even more.
Still, the effect is a useful thing to know about yourself. When something grows on you, it is worth asking whether it got better, or just more familiar.
According to the 1989 review, when did the mere exposure effect usually reach its peak?
Simply encountering something again and again tends to make us like it more, even when we don't remember having seen it.
