Research showed that repeated exposure to stimuli resulted in an affective preference for stimuli seen before (e.g., Zajonc, 1968). This finding has been called the mere exposure-effect.
One explanation is „the warm glow of recognition“: People recognize a stimulus and therefore like it more.
The goal of the study by Kunst-Wilson & Zajonc was to show that repeated exposure results in higher preference for the presented stimulus even if people are not able to recognize the stimulus.
In studies of interpersonal attraction, the more often a person is seen by someone, the more pleasing and likeable that person appears to be.