The power of behavioural science nudges (and how to use them)

Kev Kelly
September 2023

Behavioural science is the study of cognitive processes and behaviour. We can use it to influence people: to get them to vote for Brexit, to donate their organs, or to download an app. It’s a fascinating field and one you can use to improve the appeal and effectiveness of your messaging, marketing, product, or service.

Here we explain what nudges are, and how to use them in healthcare or any sector, in order to make your audience do what you want them to.

This insight was gained from our fascinating talk with behavioural science guru and Sunday Times bestselling author Patrick Fagan, along with some of our own behavioural science strategies and habit building principles (featured at the end) that we have used in digital health products and within service design.  

What is behavioural science?

Behavioural science takes psychological theory and uses it in the real world to improve things like adverts, messages, emails, and websites. Indeed it can be used to improve the design and wording choices used for pretty much anything (for example menu design).  

What is nudging?

Nudges are ways of presenting information, framing information, and crafting messages, in order to influence behaviour in a particular direction.

The term is used in behavioural science (and behavioural economics) and is defined as “any aspect of the choice architecture that alters people's behaviour in a predictable way”.

We are all known as “cognitive misers”, in that we have very limited mental capacity against infinite choice and information, and therefore we can’t process everything rationally. For example, one study found that we face 200 food choices a day (what we can eat, where, how etc.), and as such we don’t have time to think about everything, and instead we let our brain decide for us.

And the way that brains decide things, we can influence with nudges - images and / or words that persuade people to do something.

You have to cut through

In day to day life we miss a lot, we don’t see it, process it, consider it. We tend to rely on habit or inertia. Therefore if we’re creating messages / experiences / products / services that we want people to actually stop and consider, then we need to cut through the daily white noise that our audience is sleepwalking through.

The key ways to hack someone’s brain in order to grab their attention is to be bright, hit their senses, and engage with them emotionally (this is used widely in advertising).

I like the easy option

Because we have limited attention and processing power, we’re quite lazy, and tend to go for the easy option. This is key for design, as it means we have to make things as easy as possible for our audience, customers, or users, to say yes to or go forward with.

We rely on heuristics, subconscious shortcuts, and rules of thumb. If you’re on a street and trying to decide what restaurant to eat in, you’ll most likely choose the one that’s busy rather than the one that’s empty.

This heuristic is known as social proof, where we tend to follow the crowd, and do what everyone else is doing. And it’s for good reason, generally it makes sense and can be the sensible thing to do, but we can also tap into this tendency to increase our influence.  

Ooh that’s a bargain!

If you understand subconscious biases and heuristics you can design nudges around them.

This can be seen in pricing options presented to an audience. By showing a healthy discount in anything from a supermarket offer to a multinational deal, if it is communicated effectively as good value and a BIG cost saving, then it’s more likely that people will buy it.

Behavioural science in healthcare

One study found that doctors are 19% more likely to prescribe a medication if there’s only one available. If there’s two or more then it becomes effortful, and off-putting, and less likely to prescribe anything at all.

This is a small example of how decisions and decision architecture can affect choice on the side of clinicians.

As for nudges and messaging in healthcare, there are a few that stand out:

1) The default effect. People tend to go with the safest default status quo option. So in the UK for example, organ donation (and pensions) used to both be opt-in so many people didn’t bother, but now they are default for all of us. Therefore we assume this is correct, what everyone else is doing, and we see it as the easy option too (typically we go along with it rather than take the effort to think about it and / or opt-out).  

2) The salience effect. Is our tendency to focus on items or information that are more noteworthy while ignoring those that do not grab our attention. Therefore people are more likely to treat a disease or condition if they can visually see it.

3) Loss aversion. We don’t like to lose out on anything. This can extend to an example of a patient being more likely to opt for surgery if it is framed as having a 99% survival rate, than if it’s framed as having a 1% mortality rate. Even though the information is the same, the one that leads with mortality (loss) is more off-putting to people.

Nudges save lives

A great example in healthcare messaging, of using and crafting nudges in a clever way, was the COVID-19 NHS vaccine text message.

In a message of 19 words they managed to fit in 6 nudges:

“You have reached the top of the queue and are a priority for getting a free NHS COVID-19 vaccine.”

- By saying there’s a queue it gives social proof (it sounds popular and therefore good).

- By saying you’ve reached the top of the queue it uses commitment (you feel invested, you don’t want to lose your place).

- Being at the top of the queue is also an ego nudge (you feel above others below you).

- By saying you’re a priority it’s a scarcity nudge (that demand is bigger than supply, so it feels urgent).

- By saying it’s free then there is a reciprocity nudge (you’re being given something so you’re obliged to take it, or return the favour. Plus being free makes it easy, thus no cost barrier).

- By coming from the NHS you have messenger effects (more likely to do something if delivered by someone or something you trust).

This is a great example of understanding our cognitive biases and using them to craft a short and powerful message in order to increase vaccination uptake.  

Behavioural science applied to design

When you want to change behaviour in health (or anything else) you want to rely on behaviour change models. These essentially say the same thing that Sherlock Holmes said 100 years ago, that you need:

- Means

- Motive

- And opportunity

This means you need to:

1) Make it really easy for people to do. Remove barriers or friction. For example, Amazon improved revenue by $300million a year, simply by removing the need to log-in, which represents an effort.

2) You need to understand why they would want to use it. What’s the motivation for the user, what’s in it for them? This can be functional e.g. I want to get fitter, but often it’s emotional, for example to feel safe, to belong to a group, to feel respected or admired etc.

3) Then trigger its usage in the real world. With cues and reminders. To give ample opportunities to use the product and service, or ways not to forget to use it. For example it can help to pair a new habit to an existing one, such as to not prescribe a time for medication but instead to say “with breakfast”.

How to boost app downloads

Behavioural science can help with short term wins, like getting people to download an app.

If they are searching for an app then you need to grab their attention and stand out, this can be by using bright colour that’s different to everything else, or an attractive face, or a puppy (hence the lovely image at the top of this article).

Once on the App Store product page, then proven techniques to increase the likelihood of downloads are to:

- Make imagery simple

- Use clear and short language

- If it’s fun or emotional then emojis help

- Use social proof wherever possible e.g. any awards / endorsements by experts / the high number people that have downloaded already

How to boost the appeal of your product or service

It’s important to understand your audience first: do customer research, talk to them, understand their personality traits, and then certain nudges can be applied.

There are psychological models that can be applied, such as the COM-B model (capability, opportunity, motivation - similar to the above means, motive, and opportunity). To increase reasons why people would use your product or service, how it would make them feel good to use it, along with easy and desirable ways for them to use it.

Other techniques are (as mentioned above) the messenger effect, to have someone liked and trusted as the point of contact - a friendly trusting feel, an authority (like the NHS), a thought leader, or a celebrity.

Another framework that can be explored is MINDSPACE: a framework that focuses on 9 forces that drive behaviour: Messenger, Incentives, Norms, Defaults, Salience, Priming, Affect, Commitments, Ego. In order to address further influencing factors.

Then once you have these nudges in place, it’s crucial to test them. Sometimes nudges backfire, or work for a certain personality type only, so it’s essential to test your approaches to see which ones are most effective.

Effective language for healthcare

Within language there are key principles that can help...

Concreteness. Make things  as visual and tangible as possible. For example, Donald Trump did better talking about building a wall, than about a complex or abstract immigration policy.

From a health perspective the UK government did this well by saying ‘hands, face, space’  during the pandemic, rather than talk about abstract things such as hygiene and distance. Furthermore they used short monosyllabic words, with icons to add a visual element (imagery is more attention grabbing, emotional, memorable, and persuasive than words, so try to use imagery as much as you can).


Warmth. Especially within healthcare you want to be caring, and use the word ‘we’ to foster that sense of caring, and talk to the audience directly, to say ‘you’, with warm, caring emotions and adjectives.

Competence. It’s not just clarity and kindness, within health (and other sectors) we need to be experts. Therefore to show some authority in the field use technical terms and language where relevant. You don’t want to confuse or overload, instead the aim is to give a sufficient impression of scientific credibility within the offering, but enough that the audience can understand.

Brevity. Another principle is to make language as simple as possible. The ‘Jenga principle’ is useful - if you have a sentence, how many words can you remove from it before it loses the meaning? Trim away unnecessary words to make the message simple, thus strong, thus more persuasive.

How we use behavioural science

For our service design work on the new NHS hepatitis C self-testing service we removed authentication to increase ease of access and the likelihood of hard to reach groups therefore using it.

We also applied brevity and clarity to the language used, and normalised language around hepatitis C in order to create warmth, trust, and positivity. And made the process as easy as possible and communicated that fact: “self testing is simple” to show that anyone can do it.

There was also messenger effect and positive framing used to communicate that for anyone with hepatitis C “an NHS healthcare professional will help you get treatment to cure it”.

You can explore and access the service here.

We also work to build habits into the digital health apps we create, and you can find out more about our habit building usage in our recent insight piece Why habit building is critical in health tech, with how we help to build positive habits within the highly successful mental health app Talk It Out.

If you’d like to know more about our work or see how we can help you on your project, then please email

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