Jennifer Schmidt

Many people start exploring their sexuality in college. The lessons they learn about intimacy and attraction during these years lay a foundation for the rest of their lives.

"I have students who have had sex many times drunk but have never held someone's hand," says Occidental University sociologist Lisa Wade.

Have you ever noticed that when something important is missing in your life, your brain can only seem to focus on that missing thing?

The Greek poet Archilochus wrote, "the fox knows many things, but the hedgehog knows one big thing."

There are many different interpretations of this parable, but psychologist Phil Tetlock sees it as a way of understanding two cognitive styles: Foxes have different strategies for different problems. They are comfortable with nuance; they can live with contradictions. Hedgehogs, on the other hand, focus on the big picture. They reduce every problem to one organizing principle.

Have you ever noticed that when something important is missing in your life, your brain can only seem to focus on that missing thing?

Two researchers have dubbed this phenomenon scarcity, and they say it touches on many aspects of our lives.

"It leads you to take certain behaviors that in the short term help you to manage scarcity, but in the long term only make matters worse," says Sendhil Mullainathan, an economics professor at Harvard University.