For your next negotiation, what would you pay for a gadget that shows you how well you’re engaging the other side?

It would tell you when you’ve been persuasive enough to close a deal.

It would also alert you when the other side has tuned you out, so you’d know how to take a different tack.

A team of researchers at MIT’s Media Laboratory are developing just such a device: specifically, software for cell phones and PDAs that analyzes speech patterns and tone of voice to determine how people are relating in conversation.