The history of study of agenda-setting can be traced to the first chapter of Walter Lippmann's 1922 book, "Public Opinion". In that chapter, "The World Outside And The Pictures In Our Heads", Lippmann argues that the mass media are the principal connection between events in the world and the images in the minds of the public. Without using the term "agenda-setting", Walter Lippmann was writing about what we today would call "agenda-setting". Following Lippmann, in 1963, Bernard Cohen observed that the press "may not be successful much of the time in telling people what to think, but it is stunningly successful in telling its readers what to think about. The world will look different to different people," Cohen continues, "depending on the map that is drawn for them by writers, editors, and publishers of the paper they read." As early as the 1960s, Cohen had expressed the idea that later led to formalization of agenda-setting theory by McCombs and Shaw. The stories with the strongest agenda setting influence tend to be those that involve conflict, terrorism, crime and drug issues within the United States. Those that don't include or involve the United States and politics associate negatively with public opinion. In turn, there is less concern.