Demonstrators against gun violence lying on the floor of a supermarket in Orlando, Fla., last year. : Concern about mass shootings has lifted spending on studies and attracted a new generation of researchers. In 1996, the Centers for Disease Control and Prevention stopped funding research into the causes of gun violence. And for decades the field suffered from neglect: low funding and a corresponding limited interest in academia. Then came a series of high-profile mass shootings. And donations from billionaires.