A change in how a decision is presented, without banning any option.
Putting fruit at eye level in a cafeteria is a nudge. Banning junk food is not. A nudge is any change in how a decision is presented that influences behavior in a predictable way, without banning any option or changing the underlying economic incentives.
The UK created the "Nudge Unit" (Behavioural Insights Team) in 2010, a government team dedicated to applying this principle to public policy. One of its first experiments involved modifying overdue tax collection letters by adding a line stating that most neighbors had already paid, and it raised the payment rate by several percentage points without changing the amount owed or the deadline.
A nudge doesn't eliminate any option or change its real cost, it only changes how the context of the decision is presented. It's still possible to choose any alternative, but one ends up easier or more visible than the rest.
Source: Thaler, R. H. & Sunstein, C. R. (2008). Nudge: Improving Decisions About Health, Wealth, and Happiness.
Today this approach is used in public health, retirement savings, tax compliance, and education across the region, and it's the methodological foundation of much of our Behavioral Design work.
This concept is explained in more depth in our article What is behavioral science?
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