Kristen Berman (Irrational Labs)02 October 2022

Using behavioral science to improve your product

8Frameworks

13Insights

Episode overview

Kristen Berman explains how behavioral economics combines psychology and economics to identify the predictable forces shaping user decisions. She presents Irrational Labs’ Three B’s framework—define an uncomfortably specific behavior, reduce logistical and cognitive barriers, and strengthen immediate benefits—and illustrates it with work for TikTok, One Medical, and other product teams. The conversation also emphasizes behavioral diagnosis, comparative testing, ethical incentive design, and learning from existing research before building interventions.

Key ideas

Behavioral economics treats apparently irrational choices as predictably shaped by emotion, present bias, social norms, and other psychologies.
The Three B’s framework starts with a specific target behavior, then examines barriers and the immediate benefits that can motivate action.
A behavioral diagnosis maps every step users actually take and overlays the psychology operating at each step.
Adding friction can improve outcomes when it interrupts an unwanted behavior, as TikTok’s misinformation warning reduced sharing by 24%.
Reducing choice and recommending a provider and appointment time increased One Medical bookings during onboarding by 20%.
Questions can increase conversion when they make users actively consider a product’s benefits, provided the questions are easy to answer.
Teams should test interventions comparatively and consult existing literature rather than relying only on stated user preferences.
Ethical behavioral design depends heavily on incentives, customer-aligned behavioral metrics, and longer measurement horizons.

Transcript available · source text is retained privately and is not published

Frameworks in this episode

Influence4 steps

Benefit-Priming Questions (Good Friction)

Add a step to your signup flow — a question that makes users think about the benefit — and conversion goes up.

Read →

Strategy5 steps

Evidence-First Intervention Design

Literature review, then hypothesis, then 30 variants, then relative testing — never show users one design.

Read →

Influence4 steps

Friction Injection for Behavior Suppression

To make people do less of something, add logistical AND cognitive friction at the moment of the hot decision.

Read →

Leadership4 steps

Incentive Alignment Against the Dark Side

We are what we measure. Set the team's incentive on the behavior, and lengthen its time horizon.

Read →

Influence4 steps

Right for Wrong

Get people to do the thing they already want to do — by giving them a shallower, more immediate reason.

Read →

Innovation5 steps

The Behavioral Diagnosis

A journey map on steroids: every micro-step to the behavior, with the blocking psychology named at each one.

Read →

Innovation4 steps

The Easiness Ladder: Default, Then Rule of Thumb, Then Decision

First line of defence is always a default. If you can't default it, give people a heuristic — never a calculation.

Read →

Innovation4 steps

The Three B's (Behavior, Barriers, Benefits)

Pick an uncomfortably specific behavior, strip its barriers, then engineer an immediate benefit.

Read →

People & resources mentioned

Attributed to the moment in the episode. Timestamps are approximate.

People · 10

Lenny RachitskyMentionstoday we've got another very special compilation episode something I've been pulling on more and more with the podcast and the newsletter
“welcome to Lenny's podcast I'm Lenny”
▶ Watch at ~0:30approx.
Kristen BermanMentionsKristen is the CEO and co-founder of irrational Labs where she and her team use Behavioral Science
“today my guest is Kristen Berman Kristen is the CEO and co-founder of irrational Labs”
▶ Watch at ~0:30approx.
Dan ArielyMentionsfamed behavioral Economist
“I started it in 2013 with daenery Ellie who's a famed behavioral Economist”
▶ Watch at ~4:00approx.
James ClearMentionsmentioned
“it reminds me a bit of James clears is kind of idea of creating this identity for yourself”
▶ Watch at ~10:30approx.
Dan ArielyCoinedfamed behavioral Economist
“at that time he had just written his first book predictably rational”
▶ Watch at ~16:00approx.
Robert FrankCoinedauthor Robert Frank who wrote Darwin economy
“author Robert Frank who wrote Darwin economy”
▶ Watch at ~52:30approx.
Angela DuckworthCoinedmentioned
“Stephen Dubner and Angela Duckworth come together and just answer questions about Behavior change”
▶ Watch at ~53:00approx.
Stephen DubnerCoinedmentioned
“this is by the Freakonomics Stephen Dubner and Angela Duckworth come together and just answer questions about Behavior change”
▶ Watch at ~53:00approx.
Nathan FielderMentionsthe guy behind all this who's incredibly incredibly hilarious
“have you seen Nathan for you his other show”
▶ Watch at ~53:30approx.
Chris YorkRecommendshe is a behavioral scientist designer
“Chris York so he is a behavioral scientist designer”
▶ Watch at ~55:00approx.

Resources · 39

Lenny's PodcastCoinedpodcast · Lenny Rachitsky
“welcome to Lenny's podcast I'm Lenny”
▶ Watch at ~0:30approx.
FlatfileRecommendssoftware · Flatfile
“if you'd like to learn more or get started check out flat file and flatfile.com Lenny”
▶ Watch at ~2:30approx.
WhimsicalRecommendssoftware · Whimsical
“see why product teams at leading companies call Whimsical a game changer visit whimsical.com Lenny”
▶ Watch at ~3:30approx.
Irrational LabsCoinedcompany · Kristen Berman and Dan Ariely
“a rational Labs we are a Behavioral Science Consulting and Design shop”
▶ Watch at ~4:00approx.
GoogleUsescompany · Google
“we started a lot of our work at Google we were actually embedded within Google for around three years”
▶ Watch at ~4:30approx.
TikTokUsessoftware · ByteDance
“recently we've done work with Tick Tock where we've tried to it actually accomplished decreasing misinformation share by 24”
▶ Watch at ~5:00approx.
One MedicalUsescompany
“we worked with one Medical on how to increase doctor setting doctors appointments right away during that onboarding”
▶ Watch at ~5:00approx.
Credit KarmaUsescompany
“we worked with Credit Karma on basically helping them increase set up for reoccurring deposits”
▶ Watch at ~5:00approx.
Apartment ListMentionscompany
“if you go to apartment lists they ask you questions during the sign of flow”
▶ Watch at ~12:30approx.
TytoCareUsesproduct
“it's title care which is basically a a device that lets you remotely connect to a physician”
▶ Watch at ~13:00approx.
Stitch FixMentionscompany
“so if you like do Stitch fix or actually Trunk Club has come out and said they did this”
▶ Watch at ~13:00approx.
Trunk ClubMentionscompany
“Trunk Club has come out and said they did this and it increased conversion by 133 percent”
▶ Watch at ~13:00approx.
IntuitMentionscompany
“I was a product manager at Intuit working on QuickBooks online”
▶ Watch at ~16:30approx.
QuickBooks OnlineMentionssoftware · Intuit
“I was a product manager at Intuit working on QuickBooks online”
▶ Watch at ~16:30approx.
Three BsCoinedother · Kristen Berman
“our team basically has created a model of behavior change we call the Three B's”
▶ Watch at ~18:30approx.
MicrosoftUsescompany · Bill Gates and Paul Allen
“we've used this at Google Microsoft LinkedIn”
▶ Watch at ~18:30approx.
LinkedInUseswebsite · LinkedIn
“we've used this at Google Microsoft LinkedIn”
▶ Watch at ~18:30approx.
PelotonMentionsproduct · Peloton Interactive
“if I'm Peloton pm and I'm working on the app”
▶ Watch at ~19:30approx.
AsanaMentionssoftware · Asana, Inc.
“if you're Asana and if you're trying to get someone to log a task”
▶ Watch at ~22:00approx.
Lending ClubUsescompany
“Lending Club a while ago hired me to increase their conversion flow for borrowers”
▶ Watch at ~25:00approx.
Duke UniversityMentionsplace
“I was at that time leading a Duke University lab called Common Sense lab”
▶ Watch at ~26:00approx.
Common Cents LabMentionscompany · Duke University and Dan Ariely
“I was at that time leading a Duke University lab called Common Sense lab”
▶ Watch at ~26:00approx.
Lenny's Jobs TalentRecommendswebsite · Lenny Rachitsky
“either way check out lennysjobs.com Talent”
▶ Watch at ~28:00approx.
TwitterMentionswebsite · Twitter
“Facebook and Twitter are also using to slow people down”
▶ Watch at ~31:30approx.
FacebookMentionscompany · Meta
“Facebook and Twitter are also using to slow people down”
▶ Watch at ~31:30approx.
ProlificUseswebsite
“we got users from prolific which is a a platform where you can easily test things”
▶ Watch at ~33:00approx.
Google ScholarRecommendswebsite · Google
“Google Scholar is a great place to start”
▶ Watch at ~34:00approx.
WealthfrontMentionscompany
“so wealthfront has said you know one of their key insights was when people dropped out of the flow”
▶ Watch at ~39:30approx.
ClubhouseMentionssoftware · Alpha Exploration Co.
“Clubhouse actually was an interesting example of this”
▶ Watch at ~43:30approx.
KivaUsescompany
“we added a deadline to Kiva slow for when their borrowers were signing up and we increased their conversion”
▶ Watch at ~45:30approx.
Irrational Labs Behavioral Design BootcampCoinedcourse · Irrational Labs
“we have a boot camp course which basically is a self-paced online course”
▶ Watch at ~50:00approx.
Irrational LabsMentionscompany · Kristen Berman and Dan Ariely
“yeah right celebs.com is is this is the spot”
▶ Watch at ~51:30approx.
InfluenceRecommendsbook · Robert Cialdini
“influence is also a great starter book for people getting interest in the field”
▶ Watch at ~52:00approx.
Predictably IrrationalRecommendsbook · Dan Ariely
“I would be remiss not to say particularly irrational I think this is a great starter book”
▶ Watch at ~52:00approx.
The Science of ChangeRecommendspodcast · Irrational Labs
“science of change in my actually podcast so a little self-promotion”
▶ Watch at ~52:30approx.
The Darwin EconomyRecommendsbook · Robert Frank
“I would recommend Robert Frank as an author and Darwin economy”
▶ Watch at ~52:30approx.
The RehearsalRecommendstv show · Nathan Fielder
“so I love the rehearsal”
▶ Watch at ~53:00approx.
No Stupid QuestionsRecommendspodcast · Stephen Dubner and Angela Duckworth
“the other one is no stupid questions”
▶ Watch at ~53:00approx.
Nathan for YouRecommendstv show · Nathan Fielder
“I actually like Nathan For You better”
▶ Watch at ~53:30approx.

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Insights & moments

The myth-busts, hot takes, explainers, and tools worth keeping.

Myth Buster· 1

Myth Buster11:30

When Adding Friction Increases Conversion

The rule everyone lives by is that reducing signup friction increases conversion, but Kristen shows one case where the opposite holds. Asking a user a question inserts an idea into their head, getting them to engage with the product's benefits, which raises motivation to push through later friction. Trunk Club reported this approach lifted conversion by 133 percent.

Asking a question during signup makes users think about the benefits, raising motivation
Trunk Club said question-based signup increased conversion by 133 percent
A quiz for a health device: 53% of quiz-completers purchased vs 37% who didn't complete
Use easy dropdown or multiple-choice questions, never hard open-text fields

“one example one time where this is just not true that you can actually increase friction and increase conversion”
Kristen Berman · 12:00

“when you ask a question you can insert an idea into someone's head you can get them thinking about something different”
Kristen Berman · 12:00

#conversion#signup-flow#friction#product

Hot Take· 2

Hot Take45:00

Deadlines Are A Gift

Nonprofits often resist adding deadlines because they feel harmful, but Kristen argues deadlines actually help people prioritize and follow through. Across multiple companies, adding a deadline increased the number of people who completed the desired behavior. Adding a deadline to Kiva's borrower signup flow increased their conversion.

Nonprofits resisted deadlines, fearing they'd be too hurtful
Deadlines help people prioritize a behavior they already want to do
Adding deadlines increased completion across multiple companies
A deadline on Kiva's borrower signup flow increased conversion

“sometimes we say deadlines are a gift right you're just helping people kind of prioritize this”
Kristen Berman · 45:00

“when you add deadlines and we've done this in multiple companies where you add a deadline more people do the thing”
Kristen Berman · 45:30

#deadlines#conversion#nonprofits#behavior-change

Hot Take54:00

Interviews Don't Predict Job Performance

Asked for a favorite interview question, Kristen first pushes back on interviews themselves: there's little to no evidence they predict on-the-job performance. Her team relies on skill assessments and trials to predict performance, and uses interviews only for affinity and culture fit. Her favorite culture-fit question asks what personality trait defines you that's both a strength and something to improve.

Interviews have little to no evidence for predicting job performance
Use skill assessments and trials to predict actual performance
Interviews are good for affinity and culture fit
Favorite question: a personality trait that is both your strength and your weakness

“interviews actually we know don't predict job performance so very little to no evidence and say interviews will predict how I perform on the job”
Kristen Berman · 54:00

#hiring#interviews#job-performance

Explainer· 2

Explainer06:00

What Behavioral Economics Actually Is

Kristen contrasts classical economics, which assumes people are rational and emotionless, with behavioral economics, which fuses psychology and economics. The key insight is that people make emotional, biased decisions, but they do so in predictable ways, which means those behaviors can be understood and changed.

Classical economics assumes people are rational and weigh pros and cons with no emotion
Behavioral economics combines psychology and economics
People are present-biased, overweight their present selves, and follow social norms
Irrational behavior happens in predictable ways, so it can be designed for and changed

“economics says look people are rational we make decisions with no emotion we use lots of computational energy weigh the pros and cons I mean…”
Kristen Berman · 06:00

“the good news is that we do these things in predictable ways and once you understand how and why people behave you can start to…”
Kristen Berman · 06:30

#behavioral-economics#psychology#product-design

Explainer42:30

'Right For Wrong': Giving People The Wrong Reason To Do The Right Thing

Kristen explains 'right for wrong reason' — getting people to do a behavior they want to do by supplying an immediate, unrelated motivator. People got vaccines for donuts and lottery tickets rather than to protect neighbors, and one of the biggest voting interventions is simply putting pizza in the poll line. The caveat: the end goal must genuinely be good.

People do a good behavior for an immediate, unrelated reason
Vaccine uptake rose with donuts, free marijuana, and Ohio lottery tickets
Pizza in the poll line is one of the bigger voting interventions
Ethical guardrail: the end goal itself must be good for the user

“one of the bigger voting interventions is just having pizza show up at the pole line right you're motivating people to go vote not because…”
Kristen Berman · 43:00

#motivation#immediate-benefits#behavior-change#ethics

Story· 4

Story07:00

The Most-Requested Feature That Changed Nothing

A popular fintech app's most-requested feature was budgeting, so they nearly built it on demand. Irrational Labs convinced them to run a 10,000-person experiment with a control and two budgeting variations instead. The result: zero change in average spend and zero change in spend variability, which shocked the team but not the behavioral scientists.

Budgeting was the fintech app's most-requested feature across support forums and interviews
The experiment used 10,000 people across a control and two budgeting variations
Result was zero change in average spend and zero change in spend variability
Mapping every step of a behavior reveals when a feature can't pull the weight

“and what happened nothing so they were shocked the team was shocked”
Kristen Berman · 08:00

“zero change in average spend zero change in spend variability”
Kristen Berman · 08:00

#fintech#experimentation#budgeting#product

Story25:00

How She Almost Became A Predatory Lender

Lending Club paid Kristen a large bonus only if she hit a five-point conversion bump for borrowers. Chasing that incentive, she started suggesting interventions the legal team had to shut down, becoming a predatory lender even while simultaneously running a Duke lab focused on the financial health of low-income Americans. The lesson: outcomes are driven by the incentives you set, not the tactics.

The contract paid a large bonus for a five-point conversion bump and zero otherwise
The incentive structure pushed her toward predatory suggestions the legal team blocked
She was simultaneously leading Duke's Common Sense Lab on low-income financial health
'We are what we measure' — incentives, not tactics, determine how tools get used

“over the course of working with them I became a predatory lender I was suggesting things that the legal team was like no Kristen of…”
Kristen Berman · 25:30

“I like to say kind of we are what we measure and it really matters what you measure”
Kristen Berman · 25:00

#incentives#ethics#fintech#conversion

Story29:30

How TikTok Cut Misinformation Shares By 24

TikTok asked Irrational Labs to reduce the spread of misinformation, and the team narrowed the target behavior to decreasing shares specifically. Because you want people to do something less, they added barriers: an unverified-information label plus an 'are you sure' pop-up after the share button. Citing an elevator study where a slower door pushed people to the stairs, the interventions together reduced shares by 24.

Target behavior was narrowed to decreasing shares, not likes or comments
To reduce a behavior you add barriers instead of removing them
An elevator study made the door close 16 seconds longer so people took the stairs
A label plus an 'are you sure' pop-up added logistical and cognitive friction, cutting shares by 24

“make the elevator door close 16 seconds longer so now you're getting the elevator you're annoyed it's harder to use the elevator and people went…”
Kristen Berman · 30:30

“the label on the video and the pop-up reduce shares by 24”
Kristen Berman · 31:30

#tiktok#misinformation#friction#case-study

Story35:30

One Medical: Book The First Appointment During Onboarding

For One Medical, the team defined the key behavior as booking a doctor's appointment right after signup, because users who don't set the mental model early will just call their old doctor when they get sick months later. They reduced choice by recommending a single provider with a reason, and offered limited, near-term virtual appointment slots. The onboarding intervention increased bookings by 20.

Key behavior: book an appointment immediately after signing up
Onboarding must set the mental model so users remember the app when sick later
Reduce choice: recommend one provider and explain why
Limited, near-term virtual appointment slots increased bookings by 20

“instead of having lots of choice decrease the choice recommend them one provider told them why and then recommended appointment times”
Kristen Berman · 37:30

“the onboarding intervention increased bookings by 20”
Kristen Berman · 38:00

#one-medical#onboarding#engagement#case-study

Tool· 1

Tool52:00

Kristen's Behavioral Science Book Picks

In the lightning round Kristen recommends starter books for anyone getting into behavioral science. She names Predictably Irrational and Influence as great entry points, and flags an under-talked-about pick: Robert Frank's Darwin Economy, on status, social norms, and how they drive behavior.

Predictably Irrational — great starter book for the field
Influence — another powerful starter book that can change your career
Robert Frank's Darwin Economy — under-discussed, covers status and social norms

“I would be remiss not to say particularly irrational I think this is a great starter book for people getting interested in the field influence…”
Kristen Berman · 52:00

#books#recommendations#behavioral-science

Takeaway· 3

Takeaway09:30

Defaults And Rules Of Thumb Beat Willpower

Instead of asking users to do hard cognitive work like budgeting, the first line of defense is to make the behavior easier. In personal finance the best answer is usually a default, like automatic 401K enrollment. When defaults aren't feasible, rules of thumb make decisions cognitively easier so people stay adherent.

First question in any problem: how do you make it easier for someone to do?
Defaults are why 401K auto-enrollment created US retirement savings
Rules of thumb (e.g. 'no Lyfts on weekdays') remove in-the-moment cost-benefit calculation
A heuristic isn't perfect but keeps people adherent

“in the personal finance world really the answer to most things is just default so it worked for automatic enrollment 401K the reason we have…”
Kristen Berman · 09:30

#defaults#personal-finance#behavior-change#heuristics

Takeaway26:30

Set Incentives On The Behavior, Not The Outcome

To keep product work customer-friendly, Kristen offers two tips for setting team incentives. First, tie the incentive to the specific behavior rather than raw active use or retention, since the behavior aligns better with customer outcomes. Second, lengthen the incentive's time horizon so teams optimize for long-term company and consumer interest rather than short-term bumps.

Set the KPI incentive on the behavior, which aligns with customer outcomes
Still measure active use and retention, but don't incentivize on them alone
Longer incentive duration prevents short-term-only optimizations
Quarterly targets breed short-termism; annual or longer targets protect the customer

“one would be to set the incentive on the behavior because the behavior is going to align more with the”
Kristen Berman · 26:30

“second would be increasing the duration of the incentive”
Kristen Berman · 27:00

#incentives#kpis#product-management#metrics

Takeaway33:30

Google Scholar Before You Talk To Five Users

Before interviewing a handful of users on a new problem, Kristen advises spending a day searching what has already been studied. Google Scholar and the right domain keywords will surface meta-analyses summarizing prior work. And when testing designs, never show users a single option, because they might love or hate everything; present multiple options and compare relatively.

Spend a day Googling and using Google Scholar before user interviews
Use the right domain buzzwords to find relevant meta-analyses
Never run a UX study showing just one option
Always present multiple conditions and compare which drives the target behavior

“go spend a day on the internet Googling to see what else has been done”
Kristen Berman · 33:30

“we never do a study a ux study where we're just showing people one thing”
Kristen Berman · 34:00

#research#user-research#google-scholar#testing

Key ideas

Frameworks in this episode

Benefit-Priming Questions (Good Friction)

Evidence-First Intervention Design

Friction Injection for Behavior Suppression

Incentive Alignment Against the Dark Side

Right for Wrong

The Behavioral Diagnosis

The Easiness Ladder: Default, Then Rule of Thumb, Then Decision

The Three B's (Behavior, Barriers, Benefits)

People & resources mentioned

People · 10

Resources · 39

Insights & moments

⚡Myth Buster· 1

When Adding Friction Increases Conversion

◆Hot Take· 2

Deadlines Are A Gift

Interviews Don't Predict Job Performance

✶Explainer· 2

What Behavioral Economics Actually Is

'Right For Wrong': Giving People The Wrong Reason To Do The Right Thing

❝Story· 4

The Most-Requested Feature That Changed Nothing

How She Almost Became A Predatory Lender

How TikTok Cut Misinformation Shares By 24

One Medical: Book The First Appointment During Onboarding

✦Tool· 1

Kristen's Behavioral Science Book Picks

▲Takeaway· 3

Defaults And Rules Of Thumb Beat Willpower

Set Incentives On The Behavior, Not The Outcome

Google Scholar Before You Talk To Five Users

Myth Buster· 1

Hot Take· 2

Explainer· 2

Story· 4

Tool· 1

Takeaway· 3