It looks like this is the best article on the subjetc: John Edward: Hustling the Bereaved; Investigative Files (Skeptical Inquirer November 2001)
In his latest podcast ( Blogarithms IT Conversations News: August 14, 2005 ), Doug Kaye mentioned an interesting anecdotal tidbit: People seem less interested in panel discussions at conferences than they do in single speakers. The panel discussions get lower ratings at ITConversations.com, and... there was some other reason he mentioned it, too. (Okay, so I don't remember. Sorry!) As I was listening to one of their panel discussions this morning, I had a thought: It was really hard to follow. It takes a lot of mental energy to keep up with who's-saying-what. And I don't even particular care about the who's-who; it would be even worse if I really need to know which person was making a particular point. Could that be what people are reacting to when they rate panel discussions lower than single-speaker talks?