During Tuesday night's presidential debate, Sen. Barack Obama was talking about health care, and most of 25 undecided voters in Columbus, Ohio, liked what they heard. They turned knobs on small, wireless dials in their hands -- and a graph representing their immediate reaction was aired live to about 9.2 million people watching CNN.
CNN has aired these squiggly lines live on the bottom of the screen for all of the debates held since September. Some have called the readout addictive, others find it distracting.
But live feedback graphics may have another effect. Recent psychological experiments suggest they can influence viewers' judgments. That might give tiny focus groups outsize influence, especially over undecideds. But there is a broader question: How much of our political opinions are our own?
"We don't realize how much we are influenced by other people," said Steven Fein, a social psychology professor at Williams College who has used footage from presidential debates in experiments examining how voters might be swayed. "We can't ignore what we think other people think."