During a U.S. Senate committee hearing Wednesday on the impact of social media on homeland security, former head of engineering at Twitter Alex Roetter testified, saying that "what makes this so dangerous is — there's a positive feedback loop," he explained. "Because of this feedback loop, if you have some proclivity or some interest in some topic, you'll be fed more of that," he said, as he discussed how extremism can be so easily spread on social media.