Why do People Hear Voices in Their Heads?

Meet Rachel Waddingham and meet the voices that inhabit Rachel’s head: there is three-year-old Blue who just wants to play with other children, 11-year-old Elfie who is easily offended and a panel of three critical scientists. Peter hears a voice that dictated an entire children’s book to him. Around 2% of people claim, like Rachel, to be inhabited by voices with whom they have full blown relationships. Are they all sick? What causes people to hear voices? And why have some psychologists changed their minds about the dangers of colluding with the voices?(Photo: Rachel Waddingham)