8 User Retention Tactics Tested On 300 Million Users

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Growth.Design Case Study #006 — Story Duration: 8 min

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So a few weeks ago, I was at JFK airportwaiting for a delayed flight.

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That's when I saw this familiar face in my Gmail inbox

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Awww! Poor Duo!

You shouldn't worry because—

—I'm going to Buenos Aires (Argentina) on a business trip.

Plus, I have some time to kill before my flight so...

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Re-engage with Duolingo

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Internal & External Triggers

A "trigger" is a prompt of a user to take action. There are two types of triggers:

  • Internal Triggers (e.g. places, situations, emotions, people).

  • External Triggers (e.g. emails, mobile notification, billboards, ad)

People are more susceptible to take action if the external trigger is aligned with an internal trigger.1

For example, 15-30% Duolingo students use the app to make international travel more enjoyable.2

1 Nir Eyal, "Hooked" (2014)
2Duolingo's Blog

…this email is precisely the motivation I needed!

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But now that I take a closer look

This call-to-action text is tiny & low contrast.

 The only things I can quickly scan are Duo & this huge blue banner!…

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Re-engage with Duolingo

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And that's when the plane started boarding

Oh well, let's "get back on track"!

{TAP!}

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—so I opened Duolingo while waiting in line.

I'm sure I'll be able to complete my 1st Spanish lesson before the plane even takes off.

Little did I know, I was about to get hit by a rainbow

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Re-engage with Duolingo

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Hick's Law

The time it takes to make a decision increases with the number and complexity of choices.

If you highlight one option, make sure that the other options don't compete for the user's attention.

Woaaaaah. {dizzy}

So many colorful elements...

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Complete 1st Lesson

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A simple overlay over the rest of the screen would've been great to keep me focused on the button.

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Despite all the distractions around this button, this shortcut is super convenient!

In one easy tap, I can easily start a lesson without wasting my psych to choose one! {TAP!}

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Complete 1 st Lesson

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Hehe! I like how Duo is reinforcing my behavior even in the loading screen

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Complete 1 st Lesson

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User Shaming

Making users feel bad about themselves in order to convince them to adopt a behavior is rarely a good idea.

Specific kinds of user shaming are even worst—such as manipulinks and confirmshaming1.

But overall, it's often better to avoid this kind of micro-copy altogether to avoid sliding into the Dark Side of the Force—hem, I mean Dark UX Patterns.

1 Nielsen Norman Group User Shaming (2017)

but I'm not sure how I feel about the slight shaming in the last sentence. Plus, I barely use any social media.

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onwards! {TAP!}

The first question was surprisingly easy...

"Leche".

Nailed it!…

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Complete 1 st Lesson

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A dozen questions later, as I was taking my seat in the plane

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Complete 1st Lesson

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Happy Path

Try to offer a "simplified" experience with reduced difficulty, even if you have to cheat your user flows a bit.

It's a great way to:

  • boost activation rate & engagement when onboarding new users and

  • increase user retention when resurrected users come back after a long pause.

aaaaaand done!

Is it just me or this special "review" lesson feels much easier than the last time I used Duolingo...?!

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Complete 1st Lesson

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Niiice!

I'm now one lesson away from reaching my daily goal.

I really want to activate Day 1 of my streak so…

Zeigarnik Effect

People remember uncompleted tasks better than completed tasks.

A famous UX design example of this effect is the use of progress bars to guide a user's behavior.

Unfortunately, the Zeigarnik effect was about to be side-tracked by many distractions...

…let's continue to the next lesson! {TAP!}

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Start a Duolingo streak

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100 gems in 2 minutes.

Not bad!

…but turns out that it was still far from "finished"…

Okay now… onto the
next lesson. 

I want to finish this before the plane takes off!

{TAP!}

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Start a Duolingo streak

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Uh!?

"Up Your Progress Score"?

I didn't even know I had such a thing. Plus, to be honest—

Alas, that wasn't the last interruption

No thanks! {TAP!}

this quiz sounds like some serious stuff.

I'm not ready to be tested so soon.

I just want to practice for now!

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Start a Duolingo streak

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User Segmentation

It might be beneficial to avoid suggesting Podcasts for at least 2 user segments. People who are:

  • Resurrecting: returning after a pause

  • Beginners: who just started learning

This is especially important for Duolingo's "resurrected users", as they are 20% less likely than a new user to be retained.1

This "splash screen stacking" wastes precious user psych in a very fragile moment of the customer journey.

1Duolingo's Blog
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Start a Duolingo streak

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Uhhh…

Why would I leave Duolingo to listen to a podcast now?

I'm juuust getting back into the habit of using Duolingo...

…and going from relearning the word "🥛 leche" a few moments ago

—to listening to a full podcast in Spanish…?!

That's a huuuuge jump!

Duo, you're a cool owl, but that's a bit intense buddy…

No thanks! {TAP!}

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{SIGH!}

Those last screens were intense! Also…

…I'm not even sure which lesson I should complete next…

{ scrolls down }

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Start a Duolingo streak

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Actually, I don't really care about choosing a lesson.

Maybe it's just because of the Zeigarnik Effect, but I just want to reach my daily goal to fire up my streak so

…Let's just try this one?

{TAP!}

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Start a Duolingo streak

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As the plane was preparing for departure, I blazed through the second lesson—

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Start a Duolingo streak

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...aaaand done!

Streaks: Good or Bad?

Streak dynamics can sometimes backfire. Duolingo's former Head of Growth (Gina Gotthilf) said it herself:

Streaks make people come back more, but losing a streak is also a big reason why people quit.

I lost my 80-day streak last year when I was trying to learn German, and I was so frustrated that I stopped using Duolingo. That made me [even more empathetic to our users].1

133 Voices Podcast (Oct 24, 2017)

Hopefully, this time I won't be prompted with quizzes & podcasts!

Let's see... {TAP!}

As the plane was preparing for departure, I blazed through the second lesson—

15 questions later, I completed the lesson.

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Start a Duolingo streak

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Ohhh…

So you wanna bet on a 7‑day streak, Duo?

Investment & Sunk Cost Effect

Right after a reward is the best moment to ask your user to invest a bit of their resources in anticipation of future benefits.

It makes users more likely to stick around for two reasons:

  • 1) The investment loads the next trigger (e.g. notification to remind users of their recent commitment)

  • 2) People value things more when they invest work/resources in them (a.k.a. the “Sunk Cost Effect”). 1

Duolingo confirmed that this specific "Investment Wager" step increased Day-7 retention by +14%. 2

1 Nir Eyal, "Hooked" (2014)
2 Duolingo's Blog

Being in a Spanish-speaking country for the next weeks will be a constant reminder for me anyways. Seems like a safe bet to me!

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Argentina Trip

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Alright, what should I do now?

You know, there are still so many incomplete lessons in this screen that, in a weird way

Providing Exit Points

Allow users to disengage from your product with a sense of completion.

If not, people will associate your product to a never-ending list of tasks—which may hurt your long-term user retention.

There are several ways to achieve this, here's one of them:

View Experimental Redesign

(... or just press on your keyboard)

—closing the app now would make me feel like I'm abandoning something unfinished…

…even though I already completed my daily goal.

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Argentina Trip

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Positive reinforcement by reminding the users of their progress

Behavior priming to nudge users to come back tomorrow

Fallback option with low visual weight for the power-user minority

Providing Exit Points

Allow users to disengage from your product with a sense of completion.

If not, people will associate your product to a never-ending list of tasks—which may hurt your long-term user retention.

There are several ways to achieve this
← here's one of them.

Continue the Story →

(... or just press on your keyboard)

Nudge users to leave after they completed their Daily Goal.

Objective: Increase Day-30 retention by 5%

Experiment Idea

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Anyways, I'm kinda tired, and the plane is taking off now.

I think I'll just turn off my phone and take a nap.

✈️

I recharged a bit by napping during the flight.

11 hours later, I landed safely in Argentina, but—

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Argentina Trip

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The next day, as I was running late for a meeting in downtown Buenos Aires, I received this notification

Sorry Duo!

I can't practice now…

I'm in a rush!

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Argentina Trip

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As the days went by, I spent many hours at WeWork.

My business trip got super busy and once again…

…I lost the habit of practicing Spanish despite all the notifications (and their great emojis!)

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Argentina Trip

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Until one of my last days in Argentina

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Argentina Trip

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Respecting Users' Attention

There are 3 benefits to an app filtering its own notifications:

  • 1) Users are less annoyed overall.

  • 2) You minimize the risk that users turn off notifications "forever" (if they do, good luck getting people to reactivate their notifications).

  • 3) It gives you a chance to try to resurrect the user later at a more appropriate moment.

Kudos Duolingo, it's rare that an app that relies so heavily on user retention dares implement this.

Strangely enough, it also makes me want to go back to the app to show that I am committed to learning Spanish...

Whoooaaa!

Duo is telling me that they will stop sending me notifications?...

—during a quick break in Buenos Aires' marina

…I saw something I'd never seen before—

And so dear reader...

Did you manage to identify Duolingo's top 8 user retention tactics?...

Continue to view them ➡️

Finally, an app that respects my time!

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Argentina Trip

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Pssst!
One last thing for you ➡️

Psych Level

Duolingo's email was perfectly timed with my trip to Argentina, despite its tiny button.

The rainbow of colors (and Hick's Law) were distracting, but a nice button made it easy for me to start a lesson.

My special lesson with lower difficulty made me more confident to keep going.

The Zeigarnik effect of the incomplete streak & the 100 "welcome back" gems really motivated me .

So many prompts (quiz, podcast) distracted me that I almost forgot my daily goal.

My " lesson shortcut button" disappeared & I got lost in all the lessons.

I finally completed my daily goal & started my streak.

I invested 50 gems in a bet to commit to practice for 7 days.

I was so busy with work in Argentina that it used all of my brainpower. No amount of notifications could bring me back to use any app. :-/

I faced the endless sea of lessons and had no exit point. It felt weird. It gave me this experiment idea.

Duolingo's Top 8 User Retention Tactics:

  1. 📬 Lifecycle Emails

  2.  

  3.  

  4.  

  5.  

  6.  

  7.  

  8.  

…but I was delighted to see that Duolingo decided to auto-filter their own notifications!

Overall Experience Score:

A

🚧 Reduce Friction

🏔 Lower Difficulty

🎁 "Welcome Back Reward"

🔥 Streaks

💎 Sunk-Cost Effect

📱 Phone Notification

🙊 Notification Auto-Filtering

Customer Journey

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"Duolingo's User Retention"