Sitting on a sofa in his office at the Yale Child Study Center, Ami Klin plays a movie clip on a tiny laptop. The clip stars a younger Klin, with larger glasses but the same easy smile, vying for the attention of a young girl with autism. His face inches from hers, he speaks in a warm, animated voice. But the girl never looks from the toy blocks in her hands. Suddenly, she spots an orange M&M in the far corner of the room and scoots after it.