According to a recent study from Maryland-based, Context-Based Research Group, three of five search engine users can not tell the difference between a paid listing and the traditional un-paid listings. In May 2002, the US Federal Trade Commission developed voluntary guidelines for search engines to follow that were supposed to clarify for end-users which ads were paid and which were organic, (or free). According to the study, the guidelines have made it even more difficult to distinguish paid ads as people seem not to notice the words sponsored links or featured products. When told that the listing they had selected was a paid advertisement, many of the study participants expressed negative emotions, saying they felt somewhat duped. In response, ConsumerReports.Org will be releasing a set of their own guidelines for search engines to follow when displaying paid advertisements.