Learning a second language is tough. You have to consider grammar, pronunciation, and, sometimes, words that don’t even exist in your native language. And the conventional wisdom had been: if you want a child to learn a second language, start them as young as possible. But a new study has found that there’s a little more leeway than we originally thought. We talk with Boston College assistant psychology professor Joshua Hartshorne about his and his colleagues’ research and what it means for aspiring hyperpolyglots.