We tend to find things more pleasant and attractive the more we see them. When it comes to people, we tend to find their faces more attractive the more familiar we are with them. This is called the “mere exposure effect” (or “familiarity principle”).
The mere exposure principle
By merely exposing our brains to the sight of a person, we can build pathways that make them seem more attractive to us over time. The familiarity alone is enough to make us feel better about them. (Of course, this isn’t always the case, especially when there’s bad behavior involved.)
Research on this effect goes back to the early 19th century when German Gustav philosopher and experimental psychologist Gustav Fechner and Edward B. Titchener, who studied the structure of the mind. However, early hypotheses were eventually rejected, and it wasn’t until the 1960s that they were revived.
In the 60s, Polish social psychologist Robert Zajonc found that the brain’s exposure to novel stimuli elicited a fear or avoidance response. In other words, new things make us nervous. The same is true in both humans and animals.
But he found that each time a person viewed that stimulus again, there was less fear and more interest in the object. And after repeated looks, the observing person or animal will begin to act more fondly towards the object that was once new.
The black bag experiment
Wikipedia sums up a critical experiment in 1968 best:
“Charles Goetzinger conducted an experiment using the mere-exposure effect on his class at Oregon State University. Goetzinger had a student come to class in a large black bag with only his feet visible. The black bag sat on a table in the back of the classroom. Goetzinger’s experiment was to observe if the students would treat the black bag in accordance to Zajonc’s mere-exposure effect. His hypothesis was confirmed. The students in the class first treated the black bag with hostility, which over time turned into curiosity, and eventually friendship. This experiment confirms Zajonc’s mere-exposure effect, by simply presenting the black bag over and over again to the students their attitudes were changed, or as Zajonc states “mere repeated exposure of the individual to a stimulus is a sufficient condition for the enhancement of his attitude toward it.”
This may have to do with perceptual fluency. In other words, our brain just have an easier time processing objects that they’ve already processed in the past.
However, when marketers try to use this to increase our familiarity (and propensity to buy something) by sticking it in our faces constantly, it doesn’t always work. In some cases, familiarity can breed hostility. — WTF fun facts