Why Do You Like Things More the Second Time?

The song comes on the radio and you think: this is bad. Then it comes on again. And again. And one day you catch yourself humming it.

Something happened, and it wasn’t that the song improved. You did.

This is the mere exposure effect — the phenomenon in which repeated exposure to a stimulus increases preference for that stimulus, even in the absence of any other positive associations. Just seeing or hearing something more often makes you like it more. The principle is reliable enough to have been described as one of the most robust findings in social psychology.

Zajonc’s Discovery

Robert Zajonc (pronounced ZY-awnce) at Stanford published the foundational paper in 1968. He showed subjects various stimuli — Chinese characters, meaningless words, photographs of faces — multiple times, varying how often each appeared (some were shown once, others up to 25 times). He then asked subjects which ones they preferred.

The results: more frequent stimuli were consistently rated as more pleasant. Subjects preferred stimuli they had seen more, even though they often couldn’t remember having seen them. The preference was generated by the exposure frequency, not by the ability to consciously recall the exposure.

This led to Zajonc’s strong claim: “preferences need no inferences.” Liking doesn’t require conscious evaluation or memory — it can be generated directly through repeated contact.

Why Familiarity Produces Liking

The mechanism involves processing fluency.

Processing fluency is the ease with which the brain processes a stimulus. Familiar stimuli are processed more easily — the neural pathways for interpreting them are more established, requiring less cognitive effort. High processing fluency is experienced as a positive signal.

The problem: the positive signal of high fluency gets attributed to the wrong cause. The brain experiences ease of processing, which it converts to a feeling of liking or preference, and attributes that feeling to the quality of the stimulus — “this must be good” — rather than to the real cause: “I’ve encountered this before.”

This misattribution is the mere exposure effect. The familiar stimulus feels better to process; that feeling gets interpreted as intrinsic quality.

The Unconscious Version

One of the most striking demonstrations of the effect: it works even when subjects have no conscious awareness of the exposure.

Kunst-Wilson and Zajonc (1980) showed subjects geometric shapes for subliminal durations — so brief that subjects could not consciously identify them, and scored at chance when asked to recognize them afterward. When asked which of two shapes they preferred, however, subjects reliably chose the previously shown shapes over novel ones.

They had no memory of seeing the shapes. They couldn’t identify them. But they liked them better.

This demonstrates that the mere exposure effect is not mediated by conscious memory — it’s operating at a level of perceptual processing that doesn’t require deliberate recognition. Something below the level of conscious recall tracks exposure history and converts it to preference.

The Advertising Implication

The mere exposure effect is the foundational principle behind much of advertising.

An advertisement doesn’t need to be persuasive to be effective. It doesn’t need to present evidence or arguments. It simply needs to be seen enough times. Repeated exposure creates familiarity; familiarity creates liking; liking influences purchase decisions.

This is why product placements, logo visibility, and high-frequency ad buys exist — not primarily to inform, but to create the associative familiarity that the mere exposure effect converts to preference.

The same mechanism underlies propaganda: repeated exposure to an idea, name, or image creates a baseline of familiarity that gets misattributed as evidence of quality or truth. Illusory truth effect is the specific case for factual claims: statements that have been heard before feel more true, regardless of their actual truth value. The ease of processing is misread as familiarity that validates the claim.

The Limits

The mere exposure effect is not unlimited.

Starting valence matters: if your initial reaction to something was strongly negative, repeated exposure makes things worse, not better. The effect works from neutral to mildly positive — it doesn’t override strong aversion.

Optimal exposure diminishes: very high exposure frequency (hearing the same song hundreds of times) produces satiation and decreased liking — the over-familiarity effect. The relationship between exposure and preference is an inverted U, peaking at moderate familiarity.

Awareness of manipulation matters (somewhat): if subjects are explicitly told that a stimulus is being repeated and why, the effect is weakened but not eliminated. Knowing about it doesn’t fully protect against it.

Faces and Social Preference

The mere exposure effect operates particularly strongly for faces.

You like people you’ve seen before more than people you haven’t, controlling for all other factors. Research shows that even brief, subliminal exposures to a face — too short to consciously recognize — produce subsequent preferences for that person in social interactions. People rate previously exposed faces as more attractive, more trustworthy, and more likeable.

This has unsettling implications: the feeling that you’ve “connected” with someone on first meeting may be partly a familiarity signal. The sense that someone is trustworthy may be tracking exposure history rather than actual character. The preferences you feel toward people may be partly a record of who you’ve spent time near, not an independent assessment of who they are.

You hear the song again. You don’t remember the first time. But something in you has already adjusted its position.

The song got no better.

You just processed it more easily.