The familiarity principle is the tendency among human beings to develop a preference for people and things which they see often. For instance, in relationships it tends to be the case that the more often we see someone, the more pleased we are to see that person and the more we like them.

When exposed to something new or unknown most animals exhibit a form of fear or avoidance. This is probably an evolutionary development, things which are new or unknown may very well be predators.

Repeated exposure to certain people will increase our attraction toward them. We are attracted to familiar people because we consider them to be safe and unlikely to cause harm.

We build familiarity with the people with whom you have the most contact! This most important factor is proximity. Similarity is another factor that influences who we form relationships with. We are more likely to become friends or lovers with someone who is similar to us in background, attitudes, and lifestyle. In fact, there is no evidence that opposites attract. Rather, we are attracted to people who are most like us.

Check Dr. Robert Zajonc