Rita Ora

I don't know how 'X Factor' works. I was only there as a guest judge for a day. But I watched 'The Voice' a lot; I respected how it came across on TV, and I love the freedom we get as coaches to do what we want.

The idea of critical windows extends beyond just vision, of course: almost every system in the brain has a critical window when it needs to experience certain stimuli, or it won't get wired up properly. The most obvious example is language: if you don't learn a language early on, it's nigh impossible to become truly fluent.