Typically the researchers pay the subjects. It's a very active area of research though, and many reward schemes have been used and studied. Derek goes into so

Typically the researchers pay the subjects. It's a very active area of research though, and many reward schemes have been used and studied. Derek goes into some of the research here: https://www.youtube.com/watch?v=rhgwIhB58PA https://www.youtube.com/watch?v=rhgwIhB58PA