There’s no other time in your relationship with your customers that they’re more motivated to explore and use your product than on Day 1.


  1. Momentum. On Day 1, they were triggered to download/start using your product by something. On day 2, they need to remember what that was and why they thought it was important.
  2. Sunk costs. On Day 1, the sign-up flow took a few minutes, and they want to ensure that wasn’t time wasted. They might as well explore the app and see what the new toy offers. On day 2, you have to prove yourself worthy over all the other things they could be doing.
  3. On Day 1, they have no mental model. They don’t know what to expect from you yet. On Day 1, you get to create a new mental model. On Day 2, you have to change the mental model you just created on Day 1.

Most product designers grasp the first two ideas — momentum and sunk costs. What most don’t yet grasp is the critical importance of mental models on engagement and retention outcomes.

What’s a mental model?

Basically, a mental model is a “deeply ingrained view of how the world works or doesn’t work.”

For example, we have a mental model of money. It’s often: “I work to get money, so I can spend it on basic needs and wants.” 

One reason Universal Basic Income (UBI) has had trouble gaining broad social acceptance is because it conflicts with that mental model. Instead of “I work to get money,” UBI says, “I exist, so I get money for basic needs.”

Another example: We currently have a mental model for social distancing — staying 6 feet away from other human beings. 

Now imagine I try to change your mental model of social distancing. Instead of saying it means being 6 feet apart, I tell you distance doesn’t matter — you just can’t face someone else directly. 

This would’ve been an easy change to make in March when the pandemic was just starting in the U.S. and the term “social distancing” was just coming to life. But now? It would be incredibly difficult. I’d have to fight against the 6-feet idea that has anchored itself, in addition to championing the don’t-face-someone-directly idea.

Generating the right mental model for your product

When you’re designing a new product, you get to create the mental model of it. This is a key advantage you have over existing products. The catch? You have an incredibly short time period within which to do it.

There are 3 ways to create the right mental model for your users:

Expose all the benefits right up front

As a new customer, I may only be interested in one feature of your product. However, as time goes on, my needs may change. If my mental model is only about the one feature I love today, it’ll be hard to get me to use others in the future.

To overcome this, expose the range of benefits your product offers in the onboarding flow. Users may not engage with all of them immediately, but it establishes the right mental model (that you’re not a one-trick pony). 

ClassPass does this nicely by asking me to choose what types of workouts I want to do. This builds a mental model that they offer different kinds of classes.

Screenshot from workout app

The app Notion does this by pre-creating different types of documents. At first glance, I might think Notion is just a note-taking app, but these templates make it clear I can use it for much more.

Screenshot from the mobile app called Notion

Use explicit signaling

The mental model most people have of insurance companies is that of an adversary (not a trusted friend). Many of us suspect that submitting an insurance claim will be annoying, and getting full reimbursement will be an uphill battle.

When Lemonade, a renters insurance company, launched in 2016, they wanted to change the mental model customers had of insurance companies.

Not easy.

To explicitly signal they were different, they took a big swing: they changed their own incentive model. Lemonade decided to donate some of their profits to charity, thus removing their profit incentive to deny claims. This signaled to customers that 1) they’re not a typical insurance player, and 2) they can be trusted to do the right thing.

Signaling is especially important when you’re looking to create a new mental model in an industry with an already established one. For example, Chime and Varo are online banks. To distance themselves from the “big five” (Wells Fargo, Bank of America, etc.), Chime and Varo don’t charge overdraft fees. Period. This signals to potential customers that they’re different, and creates a new mental model about how a bank should behave. 

Use implicit signaling

The language-learning app Duolingo uses specific phrasing to establish the mental model they want. “Regular: 10 minutes a day” tells you this is NOT an app that requires hours of practice a day. However, it creates the mental model that this is an app you should be using every day.

Screenshot from mobile app called Duolingo

The dating app uses empty circles to let you know you’re “doing it wrong” if you’re only messaging one or two people. They’re creating a mental model that you should be messaging multiple people.

Screenshot example of a dating mobile app

The right mental model helps both you and your customer

Mental models are a bit like windows in a house. If you look outside from one window, your view is different from another. 

As product designers, we get to build the windows, and the customers get the view! The good news is that it’s incredibly easy to build windows on Day 1 – the customer’s view is unobstructed. On Day 2, the customer is already used to the window and the view. To change it, you’d need to build a new mental model for them. It’s possible, but it’s much harder than on Day 1. 

In other words, build the right mental model from the beginning, and you’ll be a model of success.

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