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Nudge, don’t sludge.

Introducing Nudge Theory

With a few holiday days to use before April rolls around, you open your preferred hotel/house/pitch booking app, ready for a couple of nights away. There are hundreds of options. The choice is yours. But how do you choose? You might look at the reviews or the ratings, you might consider how often the property is booked or the availability on the dates you’ve picked – Hurry! Only one room left at your current date. Eventually, they reel you in with the artfully arranged towel photos. That’s it. You click, you book, you receive a confirmation email.

Given how many options you had to choose from, making the final decision was relatively easy. This may be because you were ‘nudged’. Or, as Professors Cass Sunstein and Richard Thaler coined it, you came across an app which uses Nudge Theory. In their bestselling book, “Nudge: Improving decisions about health, wealth and happiness”, they term a ‘nudge’ as a discreet behaviour tool which makes a certain behaviour more appealing. However, it in no way forbids an alternative or offers any great reward. Nudging still offers freedom of choice, while discreetly leaning its audience towards a certain positive decision. As Richard Thaler famously said, “always nudge for good.”

If only everything were so easy. If only – when wanting your money back because the hotel in question is only accessible to cars on a full moon – there wasn’t a series of digital hurdles standing between you and a refund. If only there wasn’t sludge.

Sludge theory

If Nudge Theory is the positive tap to make a good decision easier, then sludge is the opposite. 

Initially, Cass Sunstein identified ‘sludge’ as “excessive or unjustified frictions, such as paperwork burdens, that cost time or money; that may make life difficult to navigate; that may be frustrating, stigmatising, or humiliating; and that might end up depriving people of access to important goods, opportunities, and services.” (Sludge Audits, 2019)

Again, sludge is part of choice architecture. However, sludge makes a positive decision more difficult to act upon. Take, for instance, that online subscription you tripped into. After the free trial was over, how much time did it take, and how many webpages did you have to scroll through, to find out how to cancel? How about finding a travel agency’s customer service number? Then there is, of course, the refund. 

How to nudge instead of sludge

Sludge can be intentional or unintentional. Indeed, rushed decisions, non-user-friendly journeys, and policies implemented without considering audience behaviours can all lead to a sludgy experience. Businesses also weaponize sludge for profit. By creating friction barriers to keep users within a certain status quo, businesses can benefit – for a while, anyway. Generally speaking, audiences don’t have a positive sentiment towards having their time, energy and money wasted. 

On the whole, nudging is beneficial for both businesses and consumers; it gently helps customers make the right decision for them which, in turn, generates custom and customer satisfaction. Sludge, however, might generate short-term gains for businesses, but in the long run will create resentment towards the brand. Customers do not return to sludge.

So – for everyone’s sake – when being a choice architect, remember: nudge, don’t sludge.

Interested in using behavioural science to understand your audiences better? Read more about choice architecture here. Or write to us at to get started on your behavioural insights journey.

This article was written by Shayoni Lynn, CEO at Lynn.

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