Why is there so much anger on social media?

Professor Sophie Scott (UCL Institute of Cognitive Neuroscience) appears in a documentary as she has designed an experiment to scan David Baddiel’s brain while he was bombarded with tweets posted about him to see which part of his brain they stimulated.

Watch: BBC Two 'David Baddiel: Social Media, Anger and Us' (from 18 mins 30 secs), Read: Sun