We start liking something more just because it becomes familiar.
A new song on the radio doesn't catch your attention at first, but after hearing it several times you start liking it more. Familiarity reduces uncertainty, and that makes the object of repeated exposure more appealing.
In a classic study, people were shown geometric shapes or Chinese alphabet characters for milliseconds, so fast they had no conscious memory of having seen them. Even so, they later preferred those stimuli over others they had never seen. Spotify uses the same principle in its Discover Weekly and Daily Mix playlists, mixing songs you already know with new music, so the novelty feels less risky.
Familiarity reduces the uncertainty associated with something unknown. The more familiar a stimulus feels to us, the easier it is to process, and that ease translates into a stronger preference for it.
Source: Zajonc, R. B. (1968). Attitudinal Effects of Mere Exposure. Journal of Personality and Social Psychology, 9(2p2), 1-27. Spotify case: Mehrotra, R. (2021). Algorithmic Balancing of Familiarity, Similarity & Discovery in Music Recommendations. Spotify Research.
Introducing something new (a product, a brand, a message) alongside something already familiar tends to generate less resistance than presenting it in complete isolation.
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