Insights and examples from leading apps to optimise user interaction, engagement and retention.
I’m the third child in a family of four, and when we were young, my mum always used a simple trick to make us finish our plates: “It’s the last one.” Automatically, we would ALL want it. It could be anything, and it would always work.
Fast forward to 2016, I was a young, inexperienced product manager at Streetbees. Streetbees is a market research company where we had a mobile app to get users to answer questions and surveys, and we used machine learning to analyse the answers and provide insights in a dashboard for large FMCG companies.
I was trying to solve the challenge of getting users to stick with us and answer as many questions and surveys as possible. As a fresh product manager, I decided to look at what competitors were doing. I noticed that many were adding the number of spots left on the app and, without thinking twice, added it as well. We saw an improvement in our metrics; more users were starting surveys. I didn’t think much of it and moved on.
A few years ago, I had an Aha moment when I read “Nudge.” The authors worked in the Obama administration to promote policies that help individuals make better choices while respecting their freedom. They made small changes that had a huge impact. I loved it and then read more about behavioural economics and cognitive science.
Suddenly, I realised that many of the changes I had implemented in the apps I worked on relied on cognitive biases and specific design principles. It was an aha moment, and I began writing about these biases and how they are used.
Some of my favourite books 📚
Today, I’ll share how understanding user psychology, with examples from previous companies where I’ve worked, such as Wise, and from leading apps, can transform app development and user interaction. We’ll explore concepts like progressive disclosure, the labour illusion, the curiosity gap, scarcity and loss aversion to help you ethically attract and retain users more effectively.
The power of cognitive biases and design principles
What are cognitive biases?
Every time users interact with your product, they:
Filter informationSeek meaningAct within a given timeStore bits of the interaction in their memories
Let’s look at Wise, a company that makes sending money abroad cheaper and easier. When a user lands on Wise, they go through several phases:
Filtering Information: Users are presented with options like sending money, receiving money, or checking exchange rates. Their brain filters what’s most relevant at that moment.Options on Wise include adding money, converting, sending, receiving and more
2. Seeking Meaning: If they choose to send money, they need to understand how it works. What’s the exchange rate? How fast will the transfer be?
UI to convert and send money
3. Acting Within a Given Time: Whether they’re in a rush to send money to family abroad or paying for a service, time is essential.
4. Storing Information: Each step leaves a trace, building trust and loyalty, ensuring users come back. Given that users tend to evaluate an experience based on the peaks and the end of the experience, Wise adds an animation when a use completes a transfer that works as a memorable delighter.
Many people have an aversion to administrative activities like banking because they are complex, lack transparency, and mistakes can have significant consequences. Making it easy for people to understand and take action is crucial, and understanding cognitive biases and design principles can help achieve that.
Examples of cognitive biases and design principles
Let’s examine the definitions of various cognitive biases, design principles, and examples of them in successful apps to better understand where they come into play:
Progressive disclosure: An interface is easier to use when complex features are gradually revealed later.Curiosity gap: Pique users’ interest by providing just enough information to intrigue them, but not enough to satisfy their curiosity immediately.Scarcity: People place higher value on items or experiences perceived as rare or in limited supply.Labour illusion: Intentionally make certain processes appear longer or more effort-intensive than they technically need to be to enhance the customer’s perception of their value.Loss aversion: People prefer to avoid losses more than earning equivalent gains
Progressive disclosure
Definition
Users are less overwhelmed if they’re exposed to complex features later. Therefore, an interface is easier to use when complex features are gradually revealed later.
Example
Most online games use that UI principle to engage new users. Initially, the game starts with simple levels that act as a tutorial, teaching players the basic mechanics with easy-to-complete stages that provide a quick sense of achievement and encourage continued play. As players advance, the game gradually introduces new types of obstacles. This steady increase in complexity keeps the game challenging without being overwhelming, ensuring that players stay engaged as they adapt to each new element and develop new strategies.
Similarly, Revolut, an online banking app, uses the same principle. They understand the user’s intent by asking what they want to use Revolut for during onboarding and then use that information to personalise the experience by showing the most relevant features first before introducing others. When the user lands on the app for the first time, they only see three tabs: Home, Transfer, and Hub. Additional features such as Invest, Crypto, and Lifestyle are gradually introduced.
Revolut uses progressive disclosure to onboard and activate users gradually.
Labour illusion
Definition
Labour illusion is when apps make processes appear longer or more effort-intensive than they need to be, enhancing users’ perception of value.
Example
I strongly suspect that Hinge, a dating app, makes you feel like it’s handpicking your best match by artificially increasing load times when a user is landing on the app or is updating their filters.
I suspect that Hinge artificially increases the loading time. This video is at real speed and on a good wifi.
Similarly, food delivery apps shows the break down of the process involved in delivering your dish straight to your bed — sorry, table.
There’s a step-by-step update of the process (“Finding the best driver,” “Your driver is on their way,” “Your food is being prepared,” and in some cases, there’s even an animation of the food being cooked!). Technically, some of these steps, such as the matching, are quicker than the animations suggest.
This approach doesn’t aim to make you feel guilty about the delivery person struggling on their bike while you eat pasta in bed.
Instead, it makes users feel more informed and involved in the process, increasing their patience and satisfaction with the service. Additionally, it can create a sense of transparency and trust, as users see (or believe they see) the effort being made for them.
Curiosity gap
Definition
The curiosity gap intrigues users by providing just enough information to pique their interest but not enough to satisfy it immediately.
Example
This technique can boost engagement and retention as users seek to discover more content. Dating apps such as Tinder blur the profiles of people who have liked you, requiring you to subscribe to see who they are.
Headspace, a meditation app, tempts users with intriguing content; if anyone has done the “Miraculous Migration of Salmon” meditation, please contact me — I really want to know!
Instagram launched Threads a few months ago and added snippets of tempting content to encourage users to create an account on Threads and leave X.
Finally, Duolingo has a clear learning path filled with unknowns and future achievements, harnessing the curiosity gap to motivate users to continue their learning journey. The anticipation of uncovering new knowledge or achieving the next level keeps users engaged and encourages daily app usage.
Tinder blurs the profiles of people who have liked you; Headspace, tempts you with intriguing content; Threads added snippets with the start of a post that gets cut just when it was getting interesting; Duolingo has a clear learning path filled with unknowns and future achievements
Scarcity
Definition
Finally, my favourite bias, scarcity, makes people place higher value on items or experiences perceived as rare or limited.
Example
E-commerce websites like ASOS use limited-time offers and flash sales to encourage frequent visits. Bumble makes their subscription feel really premium and exclusive by adding “VIP invite”.
ASOS informs users that an item is low in stock to create scarcity and Bumble makes their subscription feel very exclusive and VIP.
This principle can be applied in various ways to boost app engagement and monetisation.
Loss aversion
Definition:
People tend to avoid losses more than they seek equivalent gains. We hate losing or letting go of what we have, even if more could be gained. Prospect theory states that a loss hurts more than an equal gain feels good. In other words, losing $1,000 “hurts” more than the joy of gaining $1,000.
Example:
Many education and fitness/well-being apps leverage loss aversion to help users form habits with a mechanism called “streaks”. Put simply, streaks are a consecutive series of actions or activities performed without interruption, representing a commitment in pursuing a particular goal or habit over time. This makes streaks a robust repetition mechanism.
Streaks can motivate users by creating two feelings: a sense of ongoing accomplishment (“I have a 100-day streak!”), and a sense of increasing loss aversion (“I need to use the app today or I’ll lose my streak!”).
The most famous example is Duolingo, the leanguage learning app, but many other education and wellness apps also employ this strategy for habit building.
We have seen some common cognitive biases and design principles and their usage in popular apps but there are many more. You can refer to this illustration to explore more of them.
Cognitive Bias Codex With Definitions 1–2, an Extension of the work of John Manoogian by Brian Rene Morrissette
Ethical considerations
Being able to change someone’s behaviour is quite a great power, and with great power comes great responsibility.
Here are a few ethical considerations to keep in mind:
Transparency: Users should be aware of how and why their data is being used and should be able to make informed choices.User Autonomy: While nudging can be a powerful tool for positive behaviour change, it’s crucial to respect user autonomy. This means providing options without manipulation, allowing users to make choices that are genuinely in their best interest, rather than solely serving the app’s metrics.Long-term impact on users: Consider the long-term effects of engagement strategies on user well-being. Are you encouraging addictive behaviours? Does the app promote meaningful engagement or just surface-level interactions? It’s essential to weigh short-term gains against potential long-term consequences for users’ mental and emotional health.Inclusivity and Fairness: Cognitive biases don’t affect all users in the same way. What works for one demographic might not work for another, and in some cases, could even be harmful. It’s important to consider diverse user experiences and ensure that your app’s engagement strategies are inclusive and fair to all users.
Wider strategy
To be effective, cognitive biases and design principles must be used as part of a larger strategy. Wise uses this framework as their own Maslow’s hierarchy of needs. If you vaguely remember your philosophy class, the short summary is that you have basic needs such as food, water, and shelter at the bottom of the pyramid, with more philosophical questions at the top. In short, there’s no point in talking philosophy and Plato to someone who is starving.
Similarly, there’s no point in applying tactics to a product that doesn’t solve a real customer problem or provide a reliable service. For Wise, the issue was sending money abroad. They solved it by making the process simple, convenient, and even fun.
Cognitive biases and design principles belong to the top of the pyramid, they can be used to make an experience delightful but don’t make up a strategy.
In conclusion:
– There are many cognitive biases and design principles to explore.
– Ethical considerations are crucial.
– They can complement, not replace, a solid strategy.
What cognitive bias and design principles can you implement in your app?
Here are some topics/websites I recommend going through
If you want to go further, I can’t recommend enough reading:
Growth design case studiesThis article about how cognitive biases shape our worldThe book Nudge: Improving Decisions About Health, Wealth, and HappinessThis article about using cognitive biases to improve conversion.
Decoding user behaviour: leveraging cognitive biases in app development was originally published in UX Collective on Medium, where people are continuing the conversation by highlighting and responding to this story.
