Thousands of people across the world who survive devastating earthquakes are living with the trauma of the disaster compounded by the experiences of aftershocks. Claudia Hammond talks to Metin Basoglu, a psychiatrist who has developed a method of mass psychological treatment for survivors of disasters like these, based on his research with over 10,000 people who lived through the Turkish earthquake of 1999. Could a single session of this kind of therapy really make a difference? How strong is the placebo effect? Can sugar pills make you feel better even when you know that's exactly what they are? Claudia talks to Ted Kaptchuk from Harvard University about his findings that for people with Irritable Bowel Syndrome, knowingly taking a placebo pill twice a day improved their symptoms. But is it the placebo or the ritual that surrounds taking it? Professor Irene Tracey, pain researcher at Oxford University, says the power of placebo is all about manipulating expectation of the person taking it. She believes this research still required deception. Her research on pain and the brain had led her to suggest that rather than using placebo, changing people's expectations of active drugs could be medically beneficial. Also - why to read someone else's emotion your own face needs to minutely mimic their facial expressions. When the brain gets feedback from the face it gets information on what that person is feeling. And why Botox, which paralyses those muscles reduces the ability to understand emotion.