
James Zimring teaches a graduate-level course on critical scientific thinking and hopes to soon offer the course to undergraduates as well. (Photo by Dan Addison, University Communications)
All it would have taken to debunk the idea was to look at the numbers. But as James Zimring says in his new book, “Partial Truths: How Fractions Distort Our Thinking,” humans generally are not great at understanding the likelihood of things.
“One of the reasons is we are storytelling creatures who predominantly use anecdotal evidence, and we are not prone to expect or seek out broad statistical data that gives the full picture of a circumstance,” said Zimring, the University of Virginia’s Thomas W. Tillack Professor of Pathology. “Misunderstanding probability has really bad outcomes.”
The Numbers Tell a Different Story
Over about five years in the 1980s there were 28 cases of adolescents who played Dungeons & Dragons and later committed murder or suicide. Then came a loud public outcry to ban the game.
“That’s a very human thing to do and it’s a good thing to do, right? Because observations begin with anecdotal evidence,” Zimring said. “If there’s an association of kids dying, we should pay attention to it.
“By 1984, 3 million teenagers were playing Dungeons & Dragons in the United States and the baseline suicide rate of adolescents overall would have been about 360 suicides each year,” he said. “So, when you look at the bottom of the fraction, at the denominator, Dungeons & Dragons was, if anything, protective. It had had the opposite effect.”
In other words, kids who played Dungeons & Dragons were less likely to commit suicide than teens as a whole.