Nudge Theory


What is it?

Nudge theory is the seminal work conducted in applied behavioural sciences. Nudges are small changes made in a system that result in improved decision-making and behaviour. They can reinforce or suggest behaviour indirectly. In this way, a person will be more likely to make a certain decision or take a certain action, but their freedom to do/choose else wise is not restricted. There is no set definition around what constitutes a nudge versus another form of behavioural change strategy. However, it is widely noted that nudges tend to be light touch, often integrated with policy, and non-intrusive.

“A nudge, as we will use the term, is any aspect of the choice architecture that alters people's behavior in a predictable way without forbidding any options or significantly changing their economic incentives. To count as a mere nudge, the intervention must be easy and cheap to avoid. Nudges are not mandates. Putting fruit at eye level counts as a nudge. Banning junk food does not.” (Thaler & Sunstein, 2008).


Thaler, R. H., & Sunstein, C. R. (2008). Nudge: Improving Decisions about Health, Wealth, and Happiness. Yale University Press.

Ariely, D. (2008). Predictably irrational. Harper Audio.

Quigley, M. (2013). Nudging for health: on public policy and designing choice architecture. Medical Law Review, 21(4), 588–621.

Related Concepts

Cues and Stimuli

Applied Psychology

Why is it important for behaviour change?

Nudges were arguably the most notable applied behavioural sciences phenomena in history. Understanding how a nudge can be applied to a system to stimulate population scale change was a pioneering finding that: 1) provided a strong case against Keynesian economic theory; 2) demonstrated how small shifts in defaults and cues can result in massive population shifts in behaviour; 3) how behavioural sciences can be applied to aid in the betterment of society.

How could you apply this theory?

Look for simple changes that you can make to the way that information is presented that does not change a persons options or limit their freedom. For example, can you make an option the default? Can you frame an option as the ‘most popular choice’? Can you use social norms in your messaging?

Example of theory applied

By changing organ donation preferences from opt-in to opt-out, some countries have increased their organ donor list by millions of citizens.