Researchers have found that between 2002 and 2010 the images and emotions that the American public associates with global warming shifted significantly. Four consecutive nationwide surveys found both increasing skepticism and growing alarm among respondents. The researchers assessed Americans’ “cognitive risk representations” including the words, thoughts, and images, and the positive or negative feelings the public associates with global warming. The study also measured the underlying values of egalitarianism and individualism, as well as a variety of political, social and demographic characteristics.