TV3 is planning to bring back the so-called worm for its election leaders' debate between John Key and Phil Goff.
The worm is used to measure the reactions of a panel of undecided voters to the debate, showing whether they like or dislike what is being said. It was last used in 2002.
TV3 is also planning to allow viewers with smart-phones to participate.
The Auckland bureau chief for 3 News, Keith Slater, says it adds an extra level of interest to the debate, and is a point of difference for TV3.
He says the worm, or reactor as TV3 calls it, may not have enormous statistical significance but the group of 50 or more uncommitted voters is a reasonable sample.
Both Labour and National say they are comfortable with the use of the worm for the head-to-head debate, which will be held just five days before the election.
