Sleep, day-dreaming, meditation – these are all different states of awareness. In these states we’re not really aware of what’s going on around us. But even when humans are awake, we take in very little about our surroundings. So this week we speak to psychologists and neuroscientists to ask, why are we conscious of so little? Presenter and producer David Edmonds Editor: Richard Knight (Photo: X-ray image of human head with lightning / Credit: Stock Photo. Getty Images)