This comes from a Wall Street Journal article titled “People Believe a ‘Fact’ That Fits Their Views Even if It’s Clearly False”:
… what we remember depends on what we believe. “People build mental models,” explains Stephan Lewandowsky, a psychology professor at the University of Western Australia, Crawley, who led the study that will be published in Psychological Science. “By the time they receive a retraction, the original misinformation has already become an integral part of that mental model, or world view, and disregarding it would leave the world view a shambles.” Therefore, he and his colleagues conclude in their paper, “People continue to rely on misinformation even if they demonstrably remember and understand a subsequent retraction.”