A UK-centered study carried out by Swiss research firm Modulum, and reported on by BBC Online, shows that one of the biggest problems with the video game rating system in the UK may be parents' inability to take it seriously. The survey, which canvassed 1,000 adults by phone and 100 customers in stores, indicated that, despite awareness of the 18 rating (the UK's equivalent of the ESRB's North American M rating), parents would often let their under-age children play games marked as such. The results, presented at the Entertainment and Leisure Software Publishers Association summit in London, revealed a number of interesting conclusions about the current rating system. Parents tend to view the ratings as a warning rather than a limit, and tend to be more concerned with the quantity of their children's game-playing, rather than the contents of the games played. This discussion comes amidst a great deal of discussion over the effects of violence in gaming, with the Harvard Medical School recently asking game developers about their attitude to adult-themed games, and the U.S. Entertaiment Software Ratings Board tweaking its ratings to "provide consumers, particularly parents, with more precise guidance on the age appropriateness of certain titles." Following its presentation, Modulum's study was met with concern from the UK game publisher and developer community: Nintendo UK manager David Yarnton commented: "We need to look at solutions and as an industry we are quite united on this."