Some of the attacks are ideological, some are not and some fall into a gray area. But the highly publicized attacks in a nightclub and restaurants in Paris, at airports in Brussels and Istanbul, and in public spaces in Mumbai may be providing troubled people already contemplating violence a spur to act, experts said, in the same way that many school shootings and other violent rampages follow close on the heels of similar incidents in the news.

“Those of us in this field, it’s the first thing we think about when we read accounts of these recent mass murders: The detailed coverage of terrorist attacks may be giving people who are vulnerable or thinking along these line ideas about what to do and how to do it,” said Madelyn Gould, a professor of epidemiology and psychiatry at Columbia…

The vast majority of people who take their lives kill only themselves, leaving no evidence that they wanted to kill others. But experts suspect that murder-suicides are subject to contagion effects from high-profile cases, though the numbers are too small to establish that statistically. Only about 1 to 2 percent of murder-suicides target random people outside immediate family or friends, said Matthew Nock, a psychologist at Harvard.

“These events seem more homicide related, with suicide as part of the process, including suicide by police,” Dr. Nock said. “But you can see, with a confluence of factors, including readily available high-capacity firearms, continuous media reporting of mass killings and terror attacks, that there’s certainly fuel for contagion.”