In 2005, the artificial intelligence researcher at the Massachusetts Institute of Technology (MIT) Media Lab set out to understand how children learn to talk.
"We wanted to understand how minds work and how they develop and how the interplay of innate and environmental influence makes us who we are and how we learn to communicate."
It was a big task and after years of research, scientists around the world had only begun to scratch the surface of it.
But now, Professor Roy is beginning to get some answers, thanks to an unconventional approach, an accommodating family and a house wired with technology.
And the research may even have kick-backs for everything from robotics to video analysis.