Hostage ransoms: To pay or not to pay?

If you're kidnapped by a terrorist group or a criminal network, your chances of survival are more or less dependent on your nationality. Why do some countries pay ransoms while others refuse to? And is it time to for countries like the US to reconsider their blanket "no cooperation with terrorists" strategy? We speak to Joel Simon, author of "We Want to Negotiate: The Secret World of Kidnapping, Hostages and Ransom".