Sure enough, a large number of psychological studies have shown that people respond to scientific or technical evidence in ways that justify their preexisting beliefs. In a classic 1979 experiment (PDF), pro- and anti-death penalty advocates were exposed to descriptions of two fake scientific studies: one supporting and one undermining the notion that capital punishment deters violent crime and, in particular, murder. They were also shown detailed methodological critiques of the fake studies—and in a scientific sense, neither study was stronger than the other. Yet in each case, advocates more heavily criticized the study whose conclusions disagreed with their own, while describing the study that was more ideologically congenial as more “convincing.”