COLOGNE — Earlier this year Xaxis, the data-driven media unit of WPP, launched a new company called Light Reaction.   Yesterday, we sat down with its head Paul Dolan for a chat about performance-based advertising and the growing relevancy among brands for its model.

This interview is part of a series of videos leading up to the DMEXCO conference in Cologne. The series is presented by 4C Insights + Teletrax.