What motivates people to sign up for clinical trials?

You may have heard the ads, asking for what are effectively human guinea pigs, people to help make medical research breakthroughs. They're after volunteers to take part in clinicial trials where they test new emerging medicines to see they're safe and effective for wider use. Often they come with payments that can run into the thousands. So is it the money that motivates people to sign on or something else and how risky is it? Dr Chris Wynne the Chief Scientific Officer for the company NZ Clinical Research spoke to Lisa Owen.