Using live worms as bait: Social influence in a UK election debate

A historic feature of the 2010 UK general election campaign was the introduction of televised election debates between the leaders of the main parliamentary parties. To help viewers evaluate voter response to the issues discussed in the debates, broadcasters made use of a methodology imported from countries that have a longer history of televised election debates. Specifically, they used a continuous response tracking measure commonly referred to as “the worm”. This measure represents the average response of a sample of undecided voters who watch the debate live and record their satisfaction with what the leaders are saying using a handset. The movements of this “worm” results in a time series of data that is plotted (superimposed) over the video of the debate; the video clip below illustrates what this looked like in the first UK election debate:
Update: (October 2012) The original clip of the ITV election debate is no longer accessible on YouTube. Instead, belowis a clip showing the use of a worm by CNN in the first US Presidential Debate of 2012.


We set out to investigate the impact of the worm on people’s ability to form their own judgements about the debates and their preferred candidate. To do this, we manipulated the worm and superimposed it on a live broadcast of the third UK election debate. Two groups of 75 viewers watched the debate; in one group, the worm favoured the incumbent Prime Minister, in the other group it favoured the leader of the Liberal Democrats. We were successful in convincing viewers that they were watching an authentic, unmanipulated debate. The photo above (on the right) shows viewers in one group (here the worm has gone into the negative portion of the graph for David Cameron).

The two clips below show ths same part of the debate as seen by particpants in the two groups. The clip on the left shows the worm that was seen by the Brown-biased group, while the clip on the left shows the worm that was seen by the Clegg-biased group.

We believe that our findings have important social and political implications. You can read the full study in PloS One here.

Colin Davis & Amina Memon (Royal Holloway, University of London), and Jeffrey Bowers (University of Bristol)