How much difference can a small change make? When it comes to changing habits, convincing someone to do something or affecting the behaviour of people without them even knowing about it, quite a lot, as we have seen with the recent Facebook scandal, where data firm Cambridge Analytica used personal data influence the way people vote.  In this week's Science Focus Podcast, BBC Focus commissioning editor Jason Goodyer speaks to David Halpern, Chief Executive of the Behavioural Insights team, about nudge theory – a psychological tool used in behavioural science to subtly influence peoples’ decisions. Hosted on Acast. See acast.com/privacy for more information.