The furor over the use of so-called enhanced interrogation techniques on suspected terrorists has remained largely dormant since 2009 when President Obama banned the practice. But in April, Jose Rodriguez, who ran the CIA’s interrogation program in the years following 9/11, rekindled the old debate. Rodriguez’s new book, Hard Measures: How Aggressive CIA Actions after 9/11 Saved American Lives, defends the agency’s harsh tactics. As he told 60 Minutes, information from such interrogations helped disrupt at least 10 large-scale terror plots. Critics dispute this point; Reuters reports that a pending Senate Intelligence Committee investigation found little evidence that the interrogation program was effective.

Until recently, most discussions about the efficacy of enhanced interrogation have relied on anecdotal evidence. Since 2009, the FBI’s High-Value Interrogation Group has sought to change that by supporting scientific research into what sort of interrogation methods work best. As the Daily Beast reports, some of that research has begun to yield preliminary results. One researcher found that high-stress interrogations measures may hinder a subject’s memory. Another found that a low-stress elicitation technique—made famous by Hans Scharff, a German interrogator during World War II—proves more effective than standard questioning approaches.