The brain holds on to false facts, even after they have been retracted
| July 18, 2011[REPRINT]
After people realize the facts have been fudged, they do their best to set the record straight: judges tell juries to forget misleading testimony; newspapers publish errata. But even explicit warnings to ignore misinformation cannot erase the damage done, according to a new study from the University of Western Australia.
Psychologists asked college students to read an account of an accident involving a busload of elderly passengers. The students were then told that, actually, those on the bus were not elderly. For some students, the information ended there. Others were told the bus had in fact been transporting a college hockey team.
And still others were warned about what psychologists call the continued influence of misinformation—that people tend to have a hard time ignoring what they first heard, even if they know it is wrong—and that they should be extra vigilant about getting the story straight.
Students who had been warned about misinformation or given the alternative story were less likely than control subjects to make inferences using the old information later—but they still erred sometimes, agreeing with statements such as “the passengers found it difficult to exit the bus because they were frail.”
This result shows that “even if you understand, remember and believe the retractions, this misinformation will still affect your inferences,” says Western Australia psychologist Ullrich Ecker, an author of the study. Our memory is constantly connecting new facts to old and tying different aspects of a situation together, so that we may still unconsciously draw on facts we know to be wrong to make decisions later. “Memory has evolved to be both stable and flexible,” Ecker says, “but that also has a downside.”
[For more on how memory relies on connections and makes inferences, see “Making Connections,” by Anthony J. Greene; Scientific American Mind, July/August 2010.]
