Ask someone if they know what 'nudge' means, and they're increasingly likely to answer 'yes'. 'Nudge' has become a watch word of behavioural science and is widely understood as being indicative of actions which steer behaviour change. But are people as familiar with the related term 'sludge'?

Perhaps not, not yet, but they would be well advised to get up to speed. 'Sludge' has come to represent the dark side of nudge ethics and is used to define and draw attention to companies who use behavioural science and nudges in ways that hurt rather than promote the welfare of consumers. Sludging includes things like hidden add-ons, or long and confusing fine print, hidden subscriptions, or bureaucratic red tape and paperwork. In short, sludge is any measure which makes it harder for a consumer to do what's in their best interest.1

Sludge was defined by Richard Thaler, this year's Nobel Laureate, who, together with Cass Sunstein, also coined the term 'nudge'. It highlights how companies can and are taking advantage of innate consumer traits and fallibilities such as inertia and inattention, knowing that they can profit off the back of consumers' weaknesses and biases.