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Dogmatic people seek less information even when uncertain -- ScienceDaily

Dogmatic individuals and moderates did not differ in their accuracy or confidence of their decisions. However, the researchers found that more dogmatic participants were more likely to decline the helpful additional information. The differences between more and less dogmatic participants were especially large when participants had little confidence in a decision. Senior author Dr Steve Fleming (Wellcome Centre for Human Neuroimaging at UCL, Max Planck UCL Centre for Computational Psychiatry & Ageing Research and UCL Experimental Psychology) said: "Previous work has found that there is a close link between how confident we feel and whether or not we seek out new information. In the current study we found that this link was weaker in more dogmatic individuals." In general, the reduced search was detrimental, with more dogmatic people being less accurate in their final judgements.
Critics have pointed out that Dr. Keys violated several basic scientific norms in his study. For one, he didn't choose countries randomly but instead selected only those likely to prove his beliefs, including Yugoslavia, Finland and Italy. Excluded were France, land of the famously healthy omelet eater, as well as other countries where people consumed a lot of fat yet didn't suffer from high rates of heart disease, such as Switzerland, Sweden and West Germany. The study's star subjects—upon whom much of our current understanding of the Mediterranean diet is based—were peasants from Crete, islanders who tilled their fields well into old age and who appeared to eat very little meat or cheese. As it turns out, Dr. Keys visited Crete during an unrepresentative period of extreme hardship after World War II. Furthermore, he made the mistake of measuring the islanders' diet partly during Lent, when they were forgoing meat and cheese. Dr. Keys therefore undercounted their consumption of saturated fat. Also, due to problems with the surveys, he ended up relying on data from just a few dozen men—far from the representative sample of 655 that he had initially selected. These flaws weren't revealed until much later, in a 2002 paper by scientists investigating the work on Crete—but by then, the misimpression left by his erroneous data had become international dogma.