AMY: But why would I choose to forget?

MANDY: Because everyone does. Everyone chooses the Forget button.

DOCTOR: Did you?

MANDY; I'm not eligible to vote yet. I'm twelve. Any time after you're sixteen, you're allowed to the see the film and make your choice. And then once every five years.

DOCTOR: And once every five years, everyone chooses to forget what they've learned. Democracy in action.