Surveillance technology, robotics and computers all feature in the work of Mexican-Canadian artist Rafael Lozano-Hemmer. As you enter the exhibition space, overhead cameras track your movements, triggering a reaction -- in one room rows of white chairs rise and fall in waves as you pass by, in another, projected images emerge from the floor in response to where you stand. Lozano-Hemmer's interactive approach is summed up most spectacularly in an installation called Pulse Room, one hundred incandescent light bulbs controlled by the heartbeat of the public. He takes us on a tour of his show at the Mexican Pavilion.