Mere Exposure Effect in Psychology: Biases & Heuristics

What Is the Mere Exposure Effect? History and Discovery

The mere exposure effect finds that people show an increased preference or liking for a stimulus the more that they are exposed to that stimulus.

The effect is most likely to occur when people have no pre-existing negative attitude toward the stimulus. It tends to be strongest when they are not aware the stimulus was presented at all.

Robert Zajonc was the first to formalize the mere exposure effect, in a landmark 1968 paper, though related findings had appeared in scattered form decades earlier.

According to Zajonc’s mere exposure hypothesis, repeated exposure to a stimulus is sufficient on its own to enhance a person’s attitude toward it.

Zajonc suggests that the relationship between exposure and liking follows a positive, decelerating curve. The more someone is exposed to a stimulus, the more they like it. The first few exposures matter most; later ones add progressively less (Zajonc, 1968).

Zajonc termed the phenomenon the “mere” exposure effect because this exposure can involve any conditions that make the stimulus perceptible to the organisms.

The hypothesis allows for other bases for liking without repetition, and that liking that derives from increased exposure can be offset by other factors.

It also does not require nor completely exclude other effects of familiarity with a stimulus.

Zajonc’s Evidence for the Mere Exposure Effect

To support his hypothesis, Zajonc discussed three types of supporting studies (1968).

These studies spanned three areas: word frequency and evaluation, interpersonal contact and attraction, and musical familiarity and liking (Harrison, 1977).

Word Frequency and Word Evaluation

Studies have found correlations between word frequency (typically obtained from Thorndike-Lorge’s (1944) count) and how people view the word’s connotation.

These experimental studies have used techniques such as varying the number of times words are shown to participants and then assessing the participant’s attitudinal reactions.

Early studies of frequency and meaning found that so-called “dirty words” had higher recognition thresholds than neutral words (McGinnies, 1949).

Howes and Solomon (1950, 1951) showed more generally that infrequent words have higher recognition thresholds than frequent ones. They explained McGinnies’s finding this way: “dirty words” simply appear less often in print (Harrison, 1977).

However, R.C. Johnson, Thomson,  and Frincke (1960) were the first to raise the possibility of a relationship between word frequency and meaning.

The researchers found that more frequent words tended to have more favorable connotations than less frequently used words.

In 26 of 30 word pairs, the high-frequency member was rated more positively than the less frequent one. Nonsense words built from familiar English letter combinations also received more favorable ratings than nonsense words without them.

To add to this prior research, Zajonc (1968) asked students to indicate which members of 154 pairs of antonyms had the most favorable meanings.

He found that over 80% of the time, the high-frequency member tended to be designated as more favorable.

Zajonc also reported that the most favorable adjectives in Gough’s (1955) list occurred more frequently than less favorable ones. The most positive personality-descriptive adjectives were likewise far more frequent than negative ones (Anderson, 1968; Zajonc, 1968; Harrison, 1977).

Zajonc found similar effects with letters combined with numbers, where more frequent (i.e., lower) numbers tended to be treated more favorably than low-frequency numbers.

However, these studies do not definitively support the mere exposure hypothesis. The causal arrow could run the other way: liking a word may increase how often it gets used, rather than frequent use causing the liking.

The “Pollyanna hypothesis” offers one explanation. People tend to talk about pleasant things more than unpleasant ones. This structures their conceptual world in a positive way (Boutcher and Osgood, 1969; Matlin and Stang, 1976; Osgood, 1964; Harrison, 1977).

Interpersonal Contact and Interpersonal Attraction

Zajonc also discussed two earlier lines of research linking exposure to interpersonal attraction.

First, studies of proximity and friendship show a clear pattern. People who live or work close to each other, and so meet repeatedly, often become friends (Festinger, Schacter, & Back, 1950; Priest & Sawyer, 1967; Segal, 1974).

Second, studies of race relations suggest interracial contact can reduce prejudice. Factors such as status inequality, competition, and cultural customs can limit this effect, though (Allport, 1954; Amir, 1969; Deutsch and Collins, 1951; Pettigrew, 1971).

Studies have shown, in general, that there is a correlation between familiarity and liking for individuals and groups.

Harrison (1969) studied liking ratings of 200 public figures and 40 fabricated individuals; the ratings correlated strongly with each person’s exposure in printed media. Stang (1975a) found a similar pattern for U.S. presidents: name recognition in archival print sources tracked closely with how favorably they were rated.

Other experiments tested this attraction effect directly. Stang (1974a) posted 0, 20, or 200 campaign posters urging students to elect a fictitious candidate as editor of a student publication.

Students who had seen the posters were more likely to vote for the publicized candidate. In a separate study using photographs, Wilson and Nakajo (1966) found that showing a person’s picture more often produced steadily more favorable ratings of personality, social appeal, and emotional stability.

To corroborate this evidence, Zajonc (1968) used pictures of men’s graduation portraits and showed them either 0, 1, 2, 5, 10, or  25 times. Those who saw the graduation portraits tended to rate the person more favorably “as a person”  (Harrison, 1977).

Baum and Nickels (1975), extending Zajonc’s original study, found that these effects also applied to women and racial minorities.

Moreland and Beach (1992) took this into the real world.

Aim: to test whether mere exposure to a real person, with no interaction at all, produces genuine interpersonal attraction.

Method: four similar-looking women acted as confederates in a large university lecture across a semester, attending 0, 5, 10 or 15 sessions each. They never spoke to any student. At term’s end, students rated each woman’s attractiveness, familiarity and similarity to themselves from photos.

Results: ratings rose with attendance. The confederate seen 15 times was rated most attractive, most familiar and most similar; the one never seen was rated lowest.

Conclusion: mere exposure to a person, without any interaction, increases liking, perceived attractiveness and even felt similarity.

A modern field test makes the mechanism explicit. Back, Schmukle and Egloff (2008) randomly assigned students to seats on the first day of a class, so some pairs were simply seen more often than others by chance alone. That bare seating exposure predicted who had become friends a year later.

Musical Selection Familiarity and Liking

Musical selections tell a different story: many studies show that low- and intermediate-frequency stimuli tend to be the best-liked (Harrison, 1977).

Several studies show that the more people hear unfamiliar music, the more positively they rate it (Bornstein and Craver-Lemley, 2017).

There is a long lineage of studies demonstrating the mere exposure effect in music. One of the earliest, Meyer (1903), found repeated plays of a novel composition raised liking four times more often than they lowered it.

Other evidence contradicts the mere exposure effect. Jakobovits (1966) used music sales as a proxy for liking. As songs were aired more frequently on the radio, their sales eventually fell.

Sales could have dwindled for other reasons, such as fans simply having already bought the song. More compellingly, Bush and Pease (1968) found that playing a song 30 times in a row polarized ratings.

More people shifted negative than positive. Skaife (1966) added that exposure can raise or lower liking, depending on the piece itself (Harrison, 1977).

Other Factors Leading to Increased Likeability

Although there are many studies presenting what appear to be mere exposure effects, controversy has arisen from their reproducibility. Harrison (1977) presents a number of variables that may lead to some studies yielding mere exposure effects while others have not.

He argues that so-called stimulus variables, presentation variables, and measurement variables interact with exposure to determine liking.

Whether or not an exposure effect is observed can partly depend on the properties of the stimuli that have been selected.

Stimulus variables can include initial or preexposure familiarity, initial or pre-exposure meaning, discriminability, recognizability, and complexity (Harrison, 1977).

Initial Familiarity

If a stimulus is already familiar, more exposure is unlikely to improve a person’s attitude toward it. Washburn et al. (1927), for example, found that exposure effects shrank or disappeared when the material was already familiar rather than new.

Maslow (1937) found the same pattern. Exposure changed attitudes toward novel paintings and names, but not toward objects that were already familiar (Harrison, 1977).

Initial Meaning

Hypotheses also suggest that the mere exposure effect depends on the stimulus’s meaning prior to when people are exposed to it.

These hypotheses assume the exposure effect changes a stimulus’s meaning, not how a person actively evaluates it (Grush, 1976; Jakobovits, 1968; Harrison, 1977).

The semantic satiation hypothesis, for example, holds that repetition drains a stimulus of meaning. Initially negative stimuli become less negative with exposure; initially positive stimuli become less pleasing.

The semantic generation interpretation argues the opposite: exposure increases meaning over time. Initially positive stimuli grow more positive with continued exposure, while initially disliked stimuli grow more negative (Harrison, 1977).

Discriminability

Zajonc, Shaver, Tavris, and Van Kreveld (1972) noted that paintings shown once before being rated were better-liked than novel paintings.

However, they also found that ratings decreased as exposure further increased.

A second experiment found that exposure shaped liking for both similar and dissimilar stimuli. Maximum liking took more exposures to reach for the less-discriminable stimuli (Harrison, 1977).

Recognizability

Researchers have argued for and against recognizability as a cause of the mere exposure effect.

For example, Moreland (1975) had subjects rate stimuli according to how recognizable and familiar stimuli were. Repetition led to an increase in recognition, greater confidence in recognition judgments, greater subjective familiarity, and greater liking.

Moreland and Zajonc (1977) tested this directly.

Aim: to test whether objective exposure frequency, or the subjective feeling of familiarity, drives the rise in liking.

Method: participants viewed Japanese ideographs shown 0, 1, 3, 9, or 27 times, then rated each one for liking and, separately, for how confident they were they had seen it before.

Results: when both measures were entered together as predictors of liking, objective exposure frequency still predicted liking. Subjective recognition did not.

Conclusion: repetition raises liking through a route that does not depend on feeling familiar.

Kunst-Wilson and Zajonc (1980) went further. They removed conscious recognition altogether.

Aim: to test whether mere exposure can raise liking even when people cannot consciously tell they have seen a stimulus before.

Method: participants viewed irregular geometric shapes flashed for about one millisecond each, too briefly to identify consciously. Later, they saw pairs: one exposed shape, one new. They said which one they recognized and, separately, which one they preferred.

Results: recognition was at chance, about 50%. Participants could not tell which shapes they had seen. Preference was not: they chose the previously exposed shape on roughly 60% of trials.

Conclusion: the mere exposure effect does not need explicit memory. It can form and show itself without any conscious identification of the stimulus at all.

Complexity

Reducing the complexity of a stimulus can also lower the likelihood of an exposure effect.

Skaife (1966) found the same pattern in music: repeating a simple tune produces less favorable reactions, while repeating a complex song can still yield exposure effects.

Berlyne, meanwhile, found greater declines over exposure when the stimuli were simple rather than complex.

Context

The ways in which stimuli are presented may also influence exposure effects.

Exposure never happens in a vacuum. The feelings a situation or context produces can become increasingly linked to the stimulus as exposure continues.

An unpleasant context should make exposure decrease liking; a pleasant one should make it increase (Burgess and Sales, 1971).

M. A. Johnson (1973) tested this directly. Participants sat on hard stools in a room that smelled of formaldehyde, heated to 35°C, and were treated harshly throughout. Exposure effects still emerged, just as strong as in a condition with none of these unpleasant conditions.

In another study, Saegert et al. (1973) had women move from cubicle to cubicle and encountered each other varying numbers of times. The exposure led to increased interpersonal attraction both in conditions where subjects tested pleasant solutions and in ones where they sampled bitter concoctions.

Context studies go beyond mere exposure alone.

Zajonc et al. (1974) showed participants photos of people labelled either “criminals” or “contributors” (people with notable scholarly or scientific achievements).

When the label was reinforced, for instance by also showing a photo of the crime, repeated exposure pulled ratings apart: contributors grew more likeable, criminals less so. When the label was not reinforced, both groups grew more likeable over time (Harrison, 1969).

Overall, these studies on context show that mere exposure and associative learning effects are independent and additive.

Exposure to a negative context can lead to disliking, but the mere exposure effect serves to inhibit this decline (Harrison, 1969).

Presentation Sequence

A stimulus exposed within a “heterogeneous” sequence, one where other stimuli are interspersed, is more likely to produce an exposure effect. A “homogeneous,” uninterrupted repetition of the same stimulus is less effective.

Berlyne (1970) was among the first to show experimentally that high-frequency stimuli declined in judged pleasantness more rapidly when presented in homogeneous sequences (Harrison, 1969).

Critical Evaluation

The mere exposure effect is one of the best-replicated findings in social psychology. It holds across stimulus types, cultures and sensory modalities, and even below conscious awareness.

Bornstein’s (1989) synthesis of roughly 200 experiments confirmed it was real and reliable. The question since has not been whether it exists. It is how the effect works, and how far repetition can be pushed before it fails.

How Mere Exposure Works: Three Explanations

Psychologists broadly agree the effect is real. They disagree on why it happens. Three accounts compete, and they are not mutually exclusive:

1. Perceptual Fluency: repetition makes a stimulus easier to process, and people mistake that ease for liking.
2. Affective Primacy: liking is a partly independent system that can form preferences without any conscious judgement at all.
3. Conditioning: each harmless repeat encounter signals safety, and that safety signal becomes attached to the stimulus.

Perceptual Fluency and Misattribution

Each time we encounter a stimulus, it becomes easier and faster to process. That growing ease is called perceptual fluency.

That fluency produces a faint, positive feeling with no obvious source. Because people cannot trace it back to fluency, they misattribute it to the stimulus: this feels good, so I must like it.

The account explains a pattern that otherwise looks strange. Exposure effects are often strongest when people cannot recognize the stimulus at all.

With no memory of a prior encounter to explain the good feeling away, people attribute that feeling to liking instead. That is exactly what Kunst-Wilson and Zajonc’s (1980) subliminal-shape result and Bornstein’s (1989) meta-analysis both found.

Affective Primacy

Zajonc drew a bolder conclusion from the same findings. He argued that affect is a partly independent system able to generate preference before any cognitive appraisal (Zajonc, 1980).

This view treats liking as a direct emotional response tuned by repetition, not a judgement about fluency at all. Zajonc put it in four words: “preferences need no inferences.” The claim launched a long debate over whether emotion can precede thought.

Conditioning and Uncertainty Reduction

A third account treats repeated exposure as a small learning experience. Each encounter with a new stimulus carries a little uncertainty. An encounter that passes without harm signals safety.

Zajonc (2001) framed this as a form of classical conditioning, in which the absence of anything bad happening acts as the reinforcing event. This explains why the effect is strongest for genuinely new stimuli, where uncertainty is highest. It fades once a stimulus is already familiar.

No single account yet explains every known moderator of the effect (Montoya et al., 2017).

Contemporary Research

The most important recent evidence overturns Zajonc’s original picture.

Aim: Montoya, Horton, Vevea, Citkowicz and Lauber (2017) set out to pin down the exact shape of the exposure-liking curve.

Method: the team meta-analysed 268 curve estimates from 81 articles, fitting a straight-line and a curved component to see whether the relationship bent downward at higher exposure.

Results: the data fit a rising slope combined with a downward curve, the signature of an inverted-U. Liking rose with exposure, peaked, and then declined. This pattern held for visual stimuli shown very briefly or for over a minute.

Conclusion: the mere exposure effect is real, but it is fundamentally an inverted-U rather than an ever-rising curve. Repetition helps, up to a point, and then it hurts.

Illustrative Examples

Exposure to New Types of Art

When the paintings of impressionists, such as Claude Monet, were first displayed, they received scathing reviews. Similarly, wide criticism followed the display of early Cubist and Expressionist works.

With time, and repeated viewings, aesthetic judgments shift. Attitudes toward the now-familiar style become more positive (Bornstein and Craver-Lemley, 2017).

Architecture

Harrison (1977) opens his account of the mere-exposure effect with an anecdote: the Eiffel Tower, a “seemingly best-loved” structure today (Coutaud and Duclair, 1956).

However, despite its widespread admiration today, the Eiffel  Tower’s construction was met with “a storm of protest” (DeVries, 1972). This early condemnation, according to scholars, was near-universal and nearly led to the tower’s demolition in the early 1900s (Coutaud and Duclair, 1956).

Harrison (1977) argues that the vastly shifting attitudes about the structure resulted from the mere exposure effect. The tower was ubiquitous and inescapable and likely to be seen day after day.

It soon became a familiar part of the skyline, and, per Zajonc’s mere-exposure hypothesis, grew more widely liked (Zajonc, 1968; Harrison, 1977).

Advertising

One of the widest applications of the mere exposure effect is in product sales.

Marketing researchers have built mere-exposure findings into many contemporary advertising campaigns (Janiszewski, 1993; Ruggieri and Boca, 2013; Bornstein and Craver-Lemley, 2017).

Janiszewski (1993), for example, found that mere exposure to a brand name or product package can make consumers view the brand more favorably.

The effect persists even when consumers cannot recall the original exposure. It also persists when that exposure to a brand name or package was incidental, with no deliberate effort to process the information at all.

Janiszewski traces these unintentional effects to preattentive processes, specifically hemispheric processing theory. This framework explains how each side of the brain contributes to language and word interpretation.

References

Allport, G. W., Clark, K., & Pettigrew, T. (1954). The nature of prejudice.

Amir, Y. (1969). Contact hypothesis in ethnic relations. Psychological Bulletin, 71(5), 319–342.

Anderson H, N. (1968). Likableness Ratings of 555 Personality – Trait Words. Journal of Personality and Social Psychology, 9(3), 272–279.

Back, M. D., Schmukle, S. C., & Egloff, B. (2008). Becoming friends by chance. Psychological Science, 19(5), 439–440. https://doi.org/10.1111/j.1467-9280.2008.02106.x

Berlyne, D. E. (1970). Novelty, complexity, and hedonic value. Attention, Perception, & Psychophysics. Psychonomic Journals, 8(5A), 279–286.

Bornstein, R. F., & Craver-Lemley, C. (2017). Mere exposure effect. In R. F. Pohl (Ed.), Cognitive illusions: Intriguing phenomena in thinking, judgment and memory  256–275

Bornstein, R. F., & D’Agostino, P. R. (1992). Stimulus recognition and the mere exposure effect. Journal of Personality and Social Psychology, 63(4), 545–552. https://doi.org/10.1037/0022-3514.63.4.545

Boucher, J., & Osgood, C. E. (1969). The pollyanna hypothesis. Journal of Verbal Learning and Verbal Behavior, 8(1), 1–8.

Burgess II, T. D., & Sales, S. M. (1971). Attitudinal effects of “mere exposure”: A reevaluation. Journal of Experimental Social Psychology, 7(4), 461-472.

Bush, P. A., & Pease, K. G. (1968). Pop records and connotative satiation: Test of Jakobovits’ theory. Psychological Reports, 23(3), 871-875.

Coutaud, R., & Duclair, J. H. (1956). Paris dans votre poche. Paris: Edition Touristiques Francaises.

Deutsch, M., & Collins, M. E. (1951). Interracial housing: A psychological evaluation of a social experiment. U of Minnesota Press.

De Vries, L., & Van Amstel, I. (1972). Victorian inventions. New York: American Heritage Press.

Festinger, L., Schachter, S., & Back, K. (1950). Social pressures in informal groups; a study of human factors in housing.

Gough, H. G. (1955). Reference handbook for the Gough adjective check list. Berkeley: University of California Institute of Personality Assessment and Research

Grush, J. E. (1976). Attitude formation and mere exposure phenomena: A nonartifactual explanation of empirical findings. Journal of Personality and Social Psychology, 33(3), 281.

Harrison, A. A. (1969). Exposure and popularity. Journal of Personality  37, 359-377.

Harrison, A. A. (1977). Mere Exposure. Advances in Experimental Social Psychology, 10(C), 39–83.

Howes, D. H., & Solomon, R. L. (1950). A note on McGinnies’ “Emotionality and perceptual defense.” Psychological Review, 57(4), 229–234.

Howes, D. H., & Solomon, R. L. (1951). Visual duration threshold as a function of word-probability. Journal of Experimental Psychology, 41(6), 401–410.

Janiszewski, C. (1993). Preattentive Mere Exposure Effects. Journal of Consumer Research, 20(3), 376.

Jakobovits, L. A. (1966). Studies of fads: I. the “Hit Parade”. Psychological Reports, 18(2), 443-450.

Jakobovits, L. A. (1968). Effects of mere exposure: A comment. Journal of Personality and Social Psychology, 9(2), 30-32.

Johnson, R. C., Thomson, C. W., & Frincke, G. (1960). Word values, word frequency, and visual duration thresholds. Psychological Review, 67(5), 332–342.

Johnson, M. A. (1973, April). The attitudinal effects of mere exposure and the experimental environment. In meeting of the Western Psychological Association, Anaheim, Cahf.

Kunst-Wilson, W. R., & Zajonc, R. B. (1980). Affective discrimination of stimuli that cannot be recognized. Science, 207(4430), 557–558. https://doi.org/10.1126/science.7352271

Maslow, A. H. (1937). The influence of familiarization on preference. Journal of Experimental Psychology, 21(2), 162.

Matlin, M. W ., & Stang, D. J. (1976). The Pollyanna principle: Affect and evaluation in language, memory and cognition. In preparation.

McGinnies, E. (1949). Emotionality and perceptual defense. Psychological Review, 56(5), 244–251.

Meyer, M. (1903). Experimental studies in the psychology of music. The American Journal of Psychology, 14(3/4), 192-214.

Montoya, R. M., Horton, R. S., Vevea, J. L., Citkowicz, M., & Lauber, E. A. (2017). A re-examination of the mere exposure effect: The influence of repeated exposure on recognition, familiarity, and liking. Psychological Bulletin, 143(5), 459–498. https://doi.org/10.1037/bul0000085

Moreland, R. L., & Beach, S. R. (1992). Exposure effects in the classroom: The development of affinity among students. Journal of Experimental Social Psychology, 28(3), 255–276. https://doi.org/10.1016/0022-1031(92)90055-O

Moreland, R. L., & Zajonc, R. B. (1977). Is stimulus recognition a necessary condition for the occurrence of exposure effects?. Journal of Personality and Social Psychology, 35(4), 191.

Osgood, C. E. (1964). Semantic differential technique in the comparative study of cultures 1. American Anthropologist, 66(3), 171-200.

Pettigrew, T. F. (1969). Racially Separate or Together? Journal of Social Issues, 25(1), 43–70.

Priest, R. F., & Sawyer, J. (1967). Proximity and peership: bases of balance in interpersonal attraction. American Journal of Sociology, 72(6), 633–649.

Ruggieri, S., & Boca, S. (2013). At the roots of product placement: The mere exposure effect. Europe’s Journal of Psychology, 9(2), 246–258.

Saegert, S., Swap, W., & Zajonc, R. B. (1973). Exposure, context, and interpersonal attraction. Journal of Personality and Social Psychology, 25(2), 234.

Segal, M. W. (1974). Alphabet and attraction: An unobtrusive measure of the effect of propinquity in a field setting. Journal of Personality and Social Psychology, 30(5), 654–657.

Skaife, A. M. (1967). The role of complexity and deviation in changing taste. unpublished Ph. D. thesis, University of Oregon.

Solomon, R. L., & Howes, D. H. (1951). Word frequency, personal values, and visual duration thresholds. Psychological Review, 58(4), 256–270.

Stang, D. J. (1974a). An analysis of the effects of political campaigning. [Conference presentation]. Southern Society for Philosophy and Psychology 66th annual meeting, Tampa.

Stang, D. J. (1975a, August). Is learning necessary for the attitudinal effects of mere exposure? [Conference presentation]. American Psychological Association Annual meeting

Thorndike, E. L., & Lorge, I. (1944). The teacher’s word book of 30,000 words.

Washburn, M. F., Child, M. S., & Abel, T. M. (1927). The effects of immediate repetition on the pleasantness or unpleasantness of music. The effects of music, 199-210.

Wilson, W., & Nakajo, H. (1965). Preference for photographs as a function of frequency of presentation. Psychonomic Science, 3(1), 577-578.

Zajonc, R. B. (1968). Attitudinal effects of mere exposure. Journal of personality and social psychology, 9(2p2), 1.

Zajonc, R. B. (1980). Feeling and thinking: Preferences need no inferences. American Psychologist, 35(2), 151–175. https://doi.org/10.1037/0003-066X.35.2.151

Zajonc, R. B. (2001). Mere exposure: A gateway to the subliminal. Current Directions in Psychological Science, 10(6), 224–228. https://doi.org/10.1111/1467-8721.00154

Zajonc, R. B., Shaver, P., Tavris, C., & Van Kreveld, D. (1972). Exposure, satiation, and stimulus discriminability. Journal of Personality and Social Psychology, 21(3), 270.

Zajonc, R. B., Crandall, R., Kail Jr, R. V., & Swap, W. (1974). Effect of extreme exposure frequencies on different affective ratings of stimuli. Perceptual and motor skills, 38(2), 667-678.