Mere Exposure Effect

Mere Exposure Effect Definition

The mere exposure effect describes the phenomenon that simply encountering a stimulus repeatedly somehow makes one like it more. Perhaps the stimulus is a painting on the wall, a melody on a radio, or a face of a person you pass by every day—somehow all these stimuli tend to “grow on you.” The mere exposure effect is technically defined as an enhancement of attitude toward a novel stimulus as a result of repeated encounters with that stimulus. Interestingly, the mere exposure effect does not require any kind of reward for perceiving the stimulus. All that is required is that the stimulus is merely shown, however briefly or incidentally, to the individual. So, for example, briefly glimpsing a picture or passively listening to a melody is enough for the picture and melody to become preferred over pictures and melodies that one has not seen or heard before. In short, contrary to the adage that familiarity breeds contempt, the mere exposure effect suggests just the opposite: Becoming familiar with a novel stimulus engenders liking for the stimulus.

Mere Exposure Effect Background

Mere Exposure EffectThe mere exposure effect was first systematically examined by Robert Zajonc, who reported his findings in the influential 1968 article “Attitudinal Effects of Mere Exposure.” He presented two kinds of evidence in support of the mere exposure effect. The first kind of evidence was correlational and established a relationship between the frequency of occurrence of certain stimuli and their evaluative meaning. For example, Zajonc reported that words with positive rather than negative meanings have a higher frequency of usage in literature, magazines, and other publications. Thus, the word pretty is used more frequently than ugly (1,195 vs. 178), on is more frequent than off (30,224 vs. 3,644), and first is more frequent than last (5,154 vs. 3,517). Similar findings have also been obtained with numbers, letters, and other apparently neutral stimuli. However, this evidence is correlational, so it is impossible to say if stimulus frequency is the cause of positive meaning or if positive meaning causes the stimulus to be used more frequently. To alleviate concerns associated with the correlational evidence, Zajonc also presented experimental evidence. For example, he performed an experiment and showed that nonsensical words as well as yearbook pictures of faces are rated more favorably after they have been merely exposed to participants. Since then, researchers have experimentally documented the mere exposure effect using a wide variety of stimuli, including simple and complex line drawings and paintings, simple and complex tonal sequences and musical pieces, geometric figures, foods, odors, and photographs of people. Interestingly, the participants in those experiments included college students, amnesic patients, rats, and even newborn chicks, suggesting that the mere exposure effect reflects a fairly fundamental aspect of psychological functioning.

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Conditions Affecting Strength

During this research, scientists have discovered several conditions that modify the strength of the mere exposure effect. Thus, the mere exposure effect is stronger when exposure durations are brief. In fact, the mere exposure effect is sometimes stronger with subliminal rather than supraliminal presentations. The mere exposure effect is also stronger when the repetition scheme is heterogeneous (i.e., with the exposures of a stimulus being interspersed with the presentations of other stimuli) rather than homogeneous (i.e., with all the exposures being of the same stimulus). Furthermore, the magnitude of the mere exposure effect reaches a peak after 10 to 20 stimulus exposures and thereafter levels off. Finally, stronger mere exposure effects are elicited by more complex stimuli and when the experimental situation is set up such that boredom is minimized. In fact, boredom and saturation can sometimes reverse the generally positive effect of mere exposure— a phenomenon certainly experienced by the reader when a massively repeated advertising jingle becomes simply annoying. Some reversals of the mere exposure effect have also been reported with stimuli that are initially negative, though it is unclear whether the increased negativity is due to exposure per se or rather to the unpleasantness that comes from repeated induction of negative affect.

Mere Exposure Effect Implications

Some studies on the mere exposure effect suggest that the phenomenon has wide-ranging personal and social implications. It may influence who people become attracted to; what products, art, and entertainment they enjoy; and even their everyday moods. Regarding interpersonal attraction, one study found that subjects shown a photograph of the same person each week for four weeks exhibited greater liking for that person than when compared with subjects shown a photograph of a different person each week. In another study, preschoolers who watched Sesame Street episodes that involved children of Japanese, Canadian, and North American Indian heritage were more likely to indicate that they would like to play with such children than were preschoolers who had not seen these episodes.

In the domain of advertising, researchers have shown that unobtrusive exposure to cigarette brands enhances participants’ brand preference and their purchase intentions. Even people’s aesthetic inclinations are shaped by mere exposure. For example, adult preferences for impressionistic paintings were found to increase as the frequency of occurrence of the images of the paintings in library books increased. In another study, subjects were incidentally exposed to various pieces of orchestral music at varying frequencies. Again, as the number of exposures to a piece of orchestral music increased, then so did the subjects’ liking ratings for the music.

Apparently, mere repeated exposure may even boost mood states of individuals. In one experiment, subjects were subliminally exposed to either 25 different Chinese ideographs (single exposure condition) or to 5 Chinese ideographs that were repeated in random sequence (repeated exposure condition). Assessment of subjects’ overall mood states indicated that those subjects in the repeated exposure condition exhibited a more positive mood than did those subjects in the single exposure condition.

Theoretical Interpretations of the Mere Exposure Effect

There are many theoretical interpretations of exactly how mere repeated exposure enhances our liking for the stimulus. One class of explanations seeks the answer in simple biological processes common to many organisms, including mammals and birds. Thus, it has been proposed that organisms respond to a novel stimulus with an initial sense of uncertainty, which feels negative. Repeated exposure can reduce such uncertainty, and thus engender more positive feelings. A related proposal suggests that organisms approach novel stimuli expecting possible negative consequences and that the absence of such consequences during repeated exposure is experienced as positive.

Finally, those biologically inspired proposals emphasize that mere familiarity with a stimulus can serve as a probabilistic cue that a stimulus is relatively safe (after all, the individual survived to see it again).

A competing class of explanations seeks the answer in more perceptual and cognitive processes and treats the mere exposure effect as a kind of implicit memory phenomenon. One proposal suggests that repeated exposure gradually strengthens a stimulus memory trace and thus enhances the ease of its later identification. This ease of perception can elicit positive affect because it allows people to better deal with the stimulus in a current situation. The positive affect created by the ease of perception may, of course, generalize to the nature of the stimulus, or participants’ own mood, explaining a relatively wide scope of mere exposure effects. Importantly, for this process to occur, participants should not know why the stimulus is easy to process. Otherwise, they are unlikely to attribute the sense of positivity from the ease of perceiving the stimulus to an actual preference for the stimulus. This idea explains why mere exposure effects are stronger when stimuli are presented subliminally and when stimuli are not recognized from the exposure phase. Furthermore, the ease of perception idea explains why the mere exposure effect is more easily obtained for more complex stimuli because their memory traces are more likely to benefit from progressive strengthening by repetition. Finally, the perceptual account of the mere exposure effect fits well with many other studies suggesting that other ways of enhancing the ease of stimulus perception of a single stimulus (e.g., via stimulus contrast, duration, clarify, or priming) tend to enhance participants’ liking for those stimuli in ways comparable to repetition.

The debate, however, over the exact mechanism by which repeated mere exposure exerts its effects is far from resolved and will no doubt be a hot topic in the psychological literature for some time to come.


  1. Bornstein, R. F. (1989). Exposure and affect: Overview and meta-analysis of research 1968-1987. Psychological Bulletin, 106, 265-289.
  2. Bornstein, R. F., & D’Agostino, P. R. (1994). The attribution and discounting of perceptual fluency: Preliminary tests of a perceptual fluency/attributional model of the mere exposure effect. Social Cognition, 12, 103-128.
  3. Lee, A. Y. (2001). The mere exposure effect: An uncertainty reduction explanation revisited. Personality and Social Psychology Bulletin, 27,1255-1266.
  4. Winkielman, P., Schwarz, N., Fazendeiro, T., & Reber, R. (2003). The hedonic marking of processing fluency: Implications for evaluative judgment. In J. Musch & K. C. Klauer (Eds.), The psychology of evaluation: Affective processes in cognition and emotion (pp. 189-217). Mahwah, NJ: Erlbaum.
  5. Zajonc, R. B. (1968). Attitudinal effects of mere exposure. Journal of Personality and Social Psychology, 9, 1-27.