Mere Exposure effect
Etymology
Demonstrated and named by psychologist Robert Zajonc in 1968. His studies showed that repeated exposure to novel shapes, faces, or nonsense words — with no reward attached, hence "mere" — was enough to raise how much people liked them.
noun · /MEER ik-SPOH-zhur ih-FEKT/
The tendency to like things more simply because you have encountered them repeatedly.
What it names
Why a song you disliked grows on you and a familiar face feels trustworthy — familiarity alone breeds fondness.
Example
The mere exposure effect is the whole logic of ad repetition: the tenth time you see the logo, it just feels reliable.
Related idea
Availability heuristic uses familiarity to judge how likely something is; the mere exposure effect uses it to judge how much you like it.