ANN ARBOR—Reading violent scriptures increases aggressive behavior, especially among believers, a new study finds. The study by University of Michigan social psychologist Brad Bushman and colleagues helps to illuminate one of the ways that violence and behavior are linked.

“To justify their actions, violent people often claim that God has sanctioned their behavior,” said Bushman, faculty associate at the U-M Institute for Social Research and lead author of the article published in the March 2007 issue of Psychological Science. “Christian extremists, Jewish reactionaries and Islamic fundamentalists all can cite scriptures that seem to encourage or at least support aggression against unbelievers.”

Bushman, who is also a U-M professor of psychology and communications studies, and colleagues at Brigham Young University and at Vrije University in the Netherlands, found the same relationship in two separate experiments detailed in the article.

The first study involved Brigham Young University students, 99 percent of whom believed in God and in the Bible. The second study involved Amsterdam students, 50 percent of whom believed in God and 27 percent of whom believed in the Bible.

After reporting their religious affiliations and beliefs, participants read a passage adapted from the King James Bible that described a woman’s brutal murder and her husband’s revenge on her attackers. Half the participants were told that the passage came from the Old Testament, half that it came from an ancient scroll found by archeologists. Half the participants from each of these groups read a version of the passage that included a sentence in which God commanded his followers to take arms against others.

After reading the passages, participants were paired with confederates of the experimenters for a simple reaction task. They were told that the winner would be able to “blast” the losing partner with noise as loud as 105 decibels, about the level of a fire alarm—a common experimental measure of aggression.

The researchers found that both the religious and secular students were more aggressive, delivering louder blasts of noise to their ostensible partners, when told that the passage they read came from the Bible. Aggressive responses also increased when participants read that God directly sanctioned violence. The increased level of aggression was greater among believers than among secularists, however.

“Our results further confirm previous research showing that exposure to violent media causes people to behave more aggressively if they identify with the violent characters than if they do not,” Bushman said.

The work also supports the view that exposure to violent scriptures may induce extremists to engage in aggressive actions. “It’s important to note that we obtained evidence supporting this hypothesis in samples of university students who were, in our estimation, not typical of the terrorists who blow up civilians,” Bushman wrote. “Even among our participants who were not religiously devout, exposure to God-sanctioned violence increased subsequent aggression. That the effect was found in such a sample may attest to the insidious power of exposure to literary scriptural violence.”

According to Bushman and colleagues, this does not mean that reading the scriptures leads to aggression. “Violent stories that teach moral lessons or that are balanced with descriptions of victims’ suffering or the aggressor’s remorse can teach important lessons and have legitimate artistic merit. But taking a single violent episode out of its overall context, as we did in these studies, can produce a significant increase in aggression.”

Established in 1948, the University of Michigan Institute for Social Research (ISR) is among the world’s oldest academic survey research organizations, and a world leader in the development and application of social science methodology. ISR conducts some of the most widely-cited studies in the nation, including the Survey of Consumer Attitudes, the National Election Studies, the Monitoring the Future Study, the Panel Study of Income Dynamics, the Health and Retirement Study, and the National Survey of Black Americans. ISR researchers also collaborate with social scientists in more than 60 nations on the World Values Surveys and other projects, and the Institute has established formal ties with universities in Poland, China and South Africa. ISR is also home to the Inter-University Consortium for Political and Social Research (ICPSR), the world’s largest computerized social science data archive. Visit the ISR web site at www.isr.umich.edu for more information.