The mere-exposure effect is a psychological phenomenon by which people tend to develop liking or disliking for things merely because they are familiar with them. In social psychology, this effect is sometimes called the familiarity principle. The effect has been demonstrated with many kinds of things, including words, Chinese characters, paintings, pictures of faces, geometric figures, and sounds. In studies of interpersonal attraction, the more often people see a person, the more pleasing and likeable they find that person.
Research
Gustav Fechner conducted the earliest known research on the effect in 1876. Edward B. Titchener also documented the effect and described the "glow of warmth" felt in the presence of something familiar; however, his hypothesis was thrown out when results showed that the enhancement of preferences for objects did not depend on the individual's subjective impressions of how familiar the objects were. The rejection of Titchener's hypothesis spurred further research and the development of current theory.
The scholar best known for developing the mere-exposure effect is Robert Zajonc. Before conducting his research, he observed that exposure to a novel stimulus initially elicits a fear/avoidance response in all organisms. Each subsequent exposure to the novel stimulus causes less fear and more interest in the observing organism. After repeated exposure, the observing organism will begin to react fondly to the once novel stimulus. This observation led to the research and development of the mere-exposure effect.
Zajonc (1960s–1990s) In the 1960s, a series of Robert Zajonc's laboratory experiments demonstrated that simply exposing participants to a familiar stimulus led them to rate it more positively than other, similar stimuli that had not been presented before. At first, Zajonc looked at language and the frequency of words used. He found that overall positive words were used more than their negative counterparts. Later, he showed similar results for liking, pleasantness, and forced-choice measures from a variety of stimuli, such as polygons, drawings, photographs of expressions, nonsense words, and idiographs.
In 1980, Zajonc proposed the affective primacy hypothesis: that affective reactions (such as liking) can be "elicited with minimal stimulus input." Through mere-exposure experiments, Zajonc sought to provide evidence for the affective-primacy hypothesis, namely that affective judgments are made without prior cognitive processes. He tested this hypothesis by presenting repeated stimuli to participants at suboptimal thresholds such that they did not show conscious awareness or recognition of the repeated stimuli (when asked whether they had seen the image, responses were at chance level), but continued to show affective bias toward the repeatedly exposed stimuli. Zajonc compared results from primes exposed longer, which allowed for conscious awareness, to stimuli shown so briefly that participants did not show conscious awareness. He found that the primes shown more briefly and not recognized prompted faster responses for liking than primes shown at conscious levels.
One experiment to test the mere-exposure effect used fertile chicken eggs. Tones of two different frequencies were played to different groups of chicks while they were still unhatched. Once hatched, each tone was played to both groups of chicks. Each set of chicks consistently chose the tone prenatally played to it.
Another experiment exposed two groups of people to Chinese characters for short times. Participants were then told that these symbols represented adjectives and were asked to rate whether the symbols held positive or negative connotations. The symbols the participants had previously seen were consistently rated more positively than those they had not. In a similar experiment, people were not asked to rate the connotations of the symbols, but to describe their mood after the experiment. Members of the group with repeated exposure to certain characters reported being in better moods than those without.
In yet another variation, participants were shown an image on a tachistoscope for a very brief duration that could not be perceived consciously. This subliminal exposure produced the same effect, though it is important to note that subliminal effects are unlikely to occur without controlled laboratory conditions.