If you are thinking about buying a new car, you suddenly see people driving them all over the roads. If you just ended a long-time relationship, every song you hear seems to be written about love. If you are having a baby, you start to see them everywhere.
Confirmation bias is seeing the world through a filter, thinking selectively.
The examples above are a sort of passive version of the phenomenon. The real trouble begins when confirmation bias distorts your active pursuit of facts.
~ David McRaney