The mere-exposure effect is a psychological idea that explains how people often begin to like or dislike things simply because they are familiar with them. In social psychology, this idea is sometimes called the familiarity principle. This effect has been shown to work with many different types of things, such as words, Chinese characters, paintings, pictures of faces, shapes, and sounds. In studies about how people feel about each other, research shows that the more often people see another person, the more they tend to find that person pleasant and likeable.
Research
Gustav Fechner did the earliest research on this effect in 1876. Edward B. Titchener also studied the effect and described the "glow of warmth" people feel when seeing something familiar. However, his idea was not supported when research showed that people’s liking for objects did not depend on how familiar they thought the objects were. When Titchener’s idea was rejected, more research began, leading to the development of current theories.
Robert Zajonc is the scholar most known for creating the mere-exposure effect. Before his research, he noticed that all living things initially react with fear or avoidance to something new. Each time they see the new thing, they feel less fear and more interest. After seeing it many times, they begin to like it. This observation led to the study of the mere-exposure effect.
In the 1960s, Zajonc’s experiments showed that people rate things they have seen before more positively than things they have not seen. At first, he studied words and found that positive words were used more often than negative ones. Later, he found similar results with other types of stimuli, such as shapes, drawings, photos, made-up words, and symbols.
In 1980, Zajonc proposed the affective primacy hypothesis, which suggests that feelings, like liking something, can happen with little information. He tested this by showing people repeated images so quickly they did not recognize them. Even without knowing they had seen the images before, they still liked them more. He compared results from images seen briefly (without recognition) to those seen longer (with recognition). People who saw images briefly liked them more quickly than those who saw them clearly.
One experiment used chicken eggs. Before hatching, chicks heard different tones. After hatching, they were played both tones, and each group chose the tone they had heard before birth. Another experiment showed people Chinese characters for short times. Later, they were asked to rate the characters as positive or negative. People who had seen the characters before rated them more positively. In another test, people who had seen the characters reported feeling happier than those who had not.
In another variation, people saw images on a device that showed them for a very short time, too fast to notice. This subliminal exposure still caused them to like the images more, though this effect usually only happens in controlled experiments.
Zajonc said the mere-exposure effect can happen without thinking, and "preferences need no inferences." This idea has led to more research on how thinking and feeling are connected. He explained that if people liked things only because of information with feelings attached, persuasion would be simple. But this is not true, as simple persuasion methods have failed. He said feelings happen faster than thinking and are often more confident. He also said thinking and feeling are separate but connected: "feeling happens early in thinking and comes from a different system in the body."
Zajonc said there is no proof that thinking comes before decisions. While many people think decisions are based on thinking, he argued decisions are often made without much thinking. He said people decide first and then find reasons to support their choices.
Charles Goetzinger tested the mere-exposure effect in his class. A student came to class in a large black bag with only his feet visible. The bag stayed in the back of the classroom. Goetzinger wanted to see if students would treat the bag as Zajonc’s theory predicted. At first, students were hostile, but over time, they became curious and eventually friendly. This experiment supported Zajonc’s theory, showing that repeated exposure can change people’s attitudes.
A review of 208 experiments found the mere-exposure effect is strong and reliable, with an effect size of r = 0.26. The effect is strongest when unfamiliar things are shown briefly. The effect usually reaches its peak after 10–20 exposures, but liking may decrease with too many exposures. For example, people often like a song more after hearing it a few times, but too many repeats can reduce this liking. A delay between seeing something and measuring liking can make the effect stronger. The effect is weaker in children and for drawings and paintings compared to other types of stimuli. One study showed that people who are initially disliked become even more disliked after repeated exposure.
Zola–Morgan tested monkeys with brain injuries. Lesions in the amygdala (a brain area that handles feelings) hurt emotional responses but not thinking. Lesions in the hippocampus (a brain area for memory) hurt thinking but not emotions.
Studies show that liking increases with more exposure but may decrease if there are too many exposures. This pattern, called an inverted-U curve, has been supported for at least thirty years.
Perceptual fluency
The mere-exposure effect suggests that seeing something many times makes it easier to understand. This ease of understanding, called perceptual fluency, leads to more positive feelings. Research has shown that repeated exposure improves perceptual fluency, which increases positive feelings in personal memories and helps with learning through experience. Later studies confirmed these findings.
Application
The most obvious use of the mere-exposure effect is in advertising. However, research about how well this effect improves people’s opinions about companies and products has shown different results. One study tested the mere-exposure effect using banner ads on a computer screen. College students read an article on the computer while banner ads appeared at the top of the screen. The results showed that students who saw the "test" banner ad more often rated it more positively than students who saw other ads less often or not at all. This research supports the idea of the mere-exposure effect.
Another study found that higher amounts of media exposure are linked to lower reputations for companies, even when the media content is mostly positive. A later review of the research concluded that exposure causes mixed feelings because it creates many different associations, some positive and some negative. Exposure is most helpful when a company or product is new and unknown to people. There may not be a perfect amount of exposure that works best for an advertisement. In a third study, researchers prepared consumers with different emotions. One group of thirsty people saw a happy face before being offered a drink, while another group saw an unpleasant face. Those who saw the happy face bought more drinks and were willing to pay more for them than those who saw the unpleasant face. This study supports Zajonc’s idea that choices do not always require deep thinking. People often choose things they like, even if they haven’t thought about them carefully.
In advertising, the mere-exposure effect suggests that people do not need to think about ads: simple repetition can create a mental impression and influence their behavior without them realizing it. One scholar explained this idea by saying, "The tendencies created by mere exposure may happen before people form opinions, meaning they do not need to think carefully to develop a preference."
The mere-exposure effect appears in many areas of decision-making. For example, many stock traders invest in companies from their own country simply because they are more familiar with them, even though other countries may offer better options. The mere-exposure effect also affects how people rate academic journals. Scholars who have published in or reviewed for a journal rate it much higher than those who have not. Research on whether mere exposure improves relationships between social groups has shown mixed results. When groups already dislike each other, more exposure can increase hostility. A study of voting patterns found that how much people see a candidate affects how many votes they receive, separate from how popular the candidate’s policies are.