17,000 people in Britain were asked by SPR 'Have you ever, when believing yourself to be completely awake, had a vivid impression of seeing or being touched by a living being or inanimate object, or of hearing a Voice: which impression, so far as you could discover, was not due to any external physical cause?' 1684 people replied positively. They were asked to give a detailed account of their experience, carefully questioned, and their stories evaluated by SPR.