How can emotion affect perception?

It's the concept of letting your emotions get the best of you, not being able to separate work from your personal life, etc. When emotions overtake you, they can affect your perception of people and things. You stop seeing clearly. The best example is when you're in love, and the love makes you blind. You can't see that the person you supposedly love is a terrible person who will eventually make you miserable (to be stereotypical). That's just one way your emotions can take away from your perception.