What is the mere exposure effect?
The mere exposure effect is the finding that repeated contact with something makes people like it more. The research runs from nonsense words in student newspapers to women attending a lecture hall.
Answer to the question
What is the mere exposure effect?
The mere exposure effect is the finding that repeated contact with something, with no reward attached, tends to make people like it more. Robert Zajonc reported it in 1968 using nonsense words, and later work showed it can occur even when people cannot recognise what they saw.
Key takeaways
- Zajonc's 1968 monograph reported that repeated exposure alone, with no reward, made attitudes towards nonsense words and symbols more positive.
- Kahneman retells a newspaper study in which words ran one, two, five, ten or twenty-five times, and the most frequent were rated most favourably.
- Kunst-Wilson and Zajonc (1980) reported that preferences formed even when exposures were too degraded for recognition.
- Bornstein's 1989 meta-analysis identified eight factors that change the size of the effect, including exposure duration and recognition.
- Moreland and Beach (1992) found that women who attended a lecture class five, ten or fifteen times were liked more as attendance rose.
None of the words meant anything, yet the ones printed most often were the ones readers later rated most favourably. Daniel Kahneman retells the experiment in Thinking, Fast and Slow. In the 1960s, small boxed notices in the student papers of two Michigan universities each held a single Turkish-sounding word, and some words ran many more times than others. Its designer, Robert Zajonc, named the pattern the mere exposure effect, and researchers have spent the decades since testing how far it reaches.
Repetition Alone Was Enough, Even Unrecognised
Zajonc's 1968 monograph stated the mere exposure effect in its plainest form. Being exposed to something again and again, with no reward and no task attached, is enough to make attitudes towards it more positive. The experiments used nonsense words and symbols, which gave participants no earlier feelings to build on, and attitudes towards them grew more positive as exposure rose. The same monograph reports that common words in everyday language tend to carry a more positive meaning than rare ones.
Kahneman describes the newspaper results as spectacular. The words appeared one, two, five, ten or twenty-five times, and the more often a word ran, the more favourably it was rated. He adds that the pattern held when Zajonc and others used Chinese ideographs, faces and random polygons. In this early form the mere exposure effect is a mild and dependable preference for the familiar over the new.
Does a person need to know they have seen the thing before? William Kunst-Wilson and Zajonc degraded the exposures until recognition was precluded, and they report that preferences for the familiar objects developed anyway. Participants in that condition could not say what they had seen, and a preference for it formed all the same.
Kahneman gives the result a central place in his account of the mere exposure effect. In his telling, Zajonc held that the effect does not depend on awareness and may be stronger for stimuli a person never consciously sees. The book also relays an experiment by an associate of Zajonc's in which fertile chicken eggs were exposed to two different tones, and the chicks that hatched gave fewer distress calls to the tone they had already heard. Kahneman uses the report to show that the response is not confined to people.
Two Explanations and Twenty Years of Data
Two readings of why the mere exposure effect occurs sit side by side. Zajonc's own, as Kahneman relays it, is that a repeated stimulus has been followed by nothing bad, so its return becomes a signal of safety. The second reading comes from the fluency literature: repeated items are processed more easily, and ease itself feels pleasant.
The second link has direct evidence. Piotr Winkielman and John Cacioppo varied how easily neutral pictures could be processed while recording activity in the cheek muscle used in smiling, and in two studies the easier pictures produced more of it. The authors suggested that this could help explain why exposure raises liking. The wider fluency account, including Kahneman's dial from ease to strain, is traced in What is cognitive ease?
By the late 1980s there were enough studies to count together. Robert Bornstein pooled the work that followed Zajonc's monograph over the next twenty years in a meta-analysis. It identified eight factors that change the size of the effect, and it also considers an evolutionary basis for the effect and proposes changes to an earlier two-factor model of it. The eight factors are:
- The type of stimulus
- The complexity of the stimulus
- The order of presentation
- How long each exposure lasts
- Whether the stimulus is recognised
- The age of the participants
- The delay before ratings are made
- The maximum number of presentations
The list turns a single finding into a set of conditions that can be varied one at a time, and the same review sets its results against earlier reviews and models of the effect. A more recent meta-analysis, by R. Matthew Montoya and colleagues, found that liking tends to rise with repeated exposure and then fall. That pattern is followed in detail in The Mere Exposure Effect Has a Ceiling.
Classrooms and Faces Outside the Lab
Most of these experiments used shapes, words and photographs. One study carried the mere exposure effect into a large university lecture course. Four women attended the course five, ten or fifteen times over a term, or not at all. At the end of the term the students rated each woman, and the more often a woman had attended, the more she was liked. Richard Moreland and Scott Beach, who ran the study, report that ratings of liking and of similarity rose with attendance while ratings of familiarity changed little.
Similarity came next. In the first of two experiments by Moreland and Zajonc, faces seen repeatedly were rated as more likeable and as more similar to the raters, and the shift in perceived similarity was largely explained by the shift in liking. In the second, false information that a person was similar to the rater made that person seem more likeable and more familiar. In both experiments, familiarity and liking moved together.
Common questions
What is the mere exposure effect?
The mere exposure effect is the finding that repeated contact with something, with no reward attached, tends to make people like it more. Robert Zajonc reported it in 1968 using nonsense words, and later work showed it can occur even when people cannot recognise what they saw.
Who discovered the mere exposure effect?
Robert Zajonc, a social psychologist, set out the mere exposure effect in a 1968 monograph in the Journal of Personality and Social Psychology. Robert Bornstein's 1989 meta-analysis later gathered the first twenty years of experiments that followed it.
Does the mere exposure effect work without noticing?
A 1980 report in Science by Kunst-Wilson and Zajonc found that preferences for familiar objects developed even when the exposures were too degraded for recognition. Later work identified recognition as one of eight factors that change how large the effect is.
Sources
Kahneman, D. (2011). Thinking, Fast and Slow. Seed book; vault hub Books/Thinking Fast and Slow.
Zajonc, R. B. (1968). “Attitudinal effects of mere exposure.” Journal of Personality and Social Psychology, 9(2, Pt. 2), 1-27. doi:10.1037/h0025848 https://doi.org/10.1037/h0025848
Kunst-Wilson, W. R., & Zajonc, R. B. (1980). “Affective discrimination of stimuli that cannot be recognized.” Science, 207(4430), 557-558. doi:10.1126/science.7352271 https://doi.org/10.1126/science.7352271
Winkielman, P., & Cacioppo, J. T. (2001). “Mind at ease puts a smile on the face: Psychophysiological evidence that processing facilitation elicits positive affect.” Journal of Personality and Social Psychology, 81(6), 989-1000. doi:10.1037/0022-3514.81.6.989 https://doi.org/10.1037/0022-3514.81.6.989
Bornstein, R. F. (1989). “Exposure and affect: Overview and meta-analysis of research, 1968-1987.” Psychological Bulletin, 106(2), 265-289. doi:10.1037/0033-2909.106.2.265 https://doi.org/10.1037/0033-2909.106.2.265
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. doi:10.1037/bul0000085 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. doi:10.1016/0022-1031(92)90055-O https://doi.org/10.1016/0022-1031%2892%2990055-O
Moreland, R. L., & Zajonc, R. B. (1982). “Exposure effects in person perception: Familiarity, similarity, and attraction.” Journal of Experimental Social Psychology, 18(5), 395-415. doi:10.1016/0022-1031(82)90062-2 https://doi.org/10.1016/0022-1031%2882%2990062-2