Why?

"Experiments demonstrate that people are more distracted when they overhear a phone conversation--where they can know only one side of the dialogue--than when they overhear two people talking and know both sides. Why does half a conversation make us more curious than a whole conversation? ... Livio interviewed scientists in several fields to explore the nature of curiosity, [examining] the lives of two of history's most curious geniuses, Leonardo da Vinci and Richard Feynman, [and talking] to people with boundless curiosity"--Amazon.com.