Experts confront many explanations for surge of killings

NEW YORK — The relentless series of mass killings across the globe poses a challenge for experts trying to analyze them without lapsing into faulty generalizations.

Terms such as contagion and copycat killing apply in some cases, not in others, they say, and in certain instances perpetrators’ terrorist ideology intersects with psychological instability.

Some of the attacks, such as the coordinated assault on multiple targets in Paris last November, were elaborately planned operations by Islamic State adherents. However, they may have contributed to some of the other attacks by troubled individuals with no established ties to the militant group.

J. Reid Meloy, a San Diego-based forensic psychologist who has served as a consultant to the FBI’s Behavioral Analysis Program, said some of the attackers appear to have identified with Islamic State as an outlet for their own seething emotions.

“In virtually every one of these cases, there was a deeply held personal grievance — loss, anger, humiliation,” Meloy said. “When they come across Islamic State material, they’re stimulated by that. They can take their personal grievance worldwide.”

Meloy said two different syndromes could be surfacing in the series of attacks — contagion, in which one attack rapidly inspires imitation attacks, and copycat incidents, in which an individual seeks to emulate a previous perpetrator.

In Germany, for example, the deadliest of four recent attacks was carried out by an 18-year-old German-Iranian who killed nine people in Munich.

Police said the young man had researched previous mass attacks, including the rampage in Norway by Anders Behring Breivik that killed 77 people exactly five years before the Munich attack.

A 2015 study by researchers at Arizona State University found significant evidence of a contagion effect in the United States.

According to the study, the likelihood of new attacks rose significantly over a two-week period after any widely publicized mass killing or school shooting.

The study’s lead author, professor Sherry Towers, said contagion likely played a role in the recent spate of killings in Europe, particularly those carried out by individuals.

“Planned, coordinated terrorist attacks are in a different class compared to lone wolf killings, since logistical matters likely play more of a role in the timing,” Towers said in an email.

“Lone wolf attacks by people who might have extremist leanings, but no solid connections to terrorist cells, and also might have other mental issues, are the types of events that would likely show more of a contagion effect.”