Denislav Jeliazkov Profile picture
May 16 13 tweets 5 min read Read on X
I LOVE design psychology.

@Apple, @NotionHQ, and @Family all exploit the same psychological loophole to dominate their competition.

It's called Jakob's Law.

Once you understand it, you'll never look at product design the same way again 🧵
Jakob's Law is simple:

Users bring expectations from EVERY other app they've used before yours.

This means people prefer your product to work the SAME WAY as products they already know.

Break this, and you're training users from scratch. Good luck with that.
Jakob's Law in practice:

When your design matches users' expectations, it feels "intuitive."

When you break it, users get that "WTF" feeling.

Suddenly they have to think about your interface instead of just using it.

Design isn't art. It's psychology.
Jakob's Law explains why the best designers don't create new patterns.

They leverage existing mental models to make products that feel familiar yet better.

Every successful app has:

• Consistent navigation placement
• Standard icons (⚙️ for settings)
• Expected button behaviors
Jakob's Law in action:

Let's look at @family:

It uses chat-like interfaces that feel like iMessage or WhatsApp. But for finance.

As a result, money management feels as intuitive as texting your friends & users INSTANTLY know how to use it without learning anything new.
@NotionHQ does the same thing:

It borrows from these apps:

@googledocs → text editing
@trello → kanban boards
@SlackHQ → commenting/collaboration

Even with all its power, it feels somehow... familiar. That's Jakob's Law working its magic.
@Apple mastered this decades ago:

• Consistent gestures across iOS
• Predictable menu placements
• Standard button behaviors

Apple rarely surprises users with HOW things work. Their "innovations" are just incremental improvements on familiar patterns. Image
Every time users have to stop and think "how do I use this?" you've lost.

People don't want to learn new UI patterns.

They want to do tasks without thinking about the interface at all.

This is why @Amazon's "Buy Now" button is always orange and always in the same spot.
Here's how I apply Jakob's Law with clients:

1. Study what apps their users already love
2. Map common interactions & patterns
3. Build on those familiar foundations
4. Only innovate where it adds clear value

It's why my designs convert better.
When should you break Jakob's Law?

Only when the existing pattern SUCKS. If you're going to break convention, make sure:

• The current standard is genuinely broken
• Your solution is 10x better
• Users can figure it out in under 5 seconds

And always incrementally...
Final thought:

Great design isn't about originality. It's about making complex things feel familiar.

Users don't notice good design. They just feel it. And isn't that the whole point?
Founders:

I’ve helped 60+ startups ship beautiful products with GOOD design.

So if you’re looking for a banging UX/UI design for your app/product...

Book a call and let’s see how I can help: cal.com/denisjeliazkov…
Liked this thread?

Give your bro @DenisJeliazkov a follow for more cool design processes & breakdowns.

And like/repost to help a fellow designer:

• • •

Missing some Tweet in this thread? You can try to force a refresh
 

Keep Current with Denislav Jeliazkov

Denislav Jeliazkov Profile picture

Stay in touch and get notified when new unrolls are available from this author!

Read all threads

This Thread may be Removed Anytime!

PDF

Twitter may remove this content at anytime! Save it as PDF for later use!

Try unrolling a thread yourself!

how to unroll video
  1. Follow @ThreadReaderApp to mention us!

  2. From a Twitter thread mention us with a keyword "unroll"
@threadreaderapp unroll

Practice here first or read more on our help page!

More from @DenisJeliazkov

Jun 19
Look at these 2 UIs.

One of them will 100% outperform the other for 1 key reason:

The Zeigarnik Effect.

Here's EVERYTHING you need to know about this psychological trick (& how to use it for your products to increase conversions): Image
The Zeigarnik Effect says our brains HATE unfinished business.

Like that TV show cliffhanger that keeps you up at night.

Or that half-filled progress bar that makes you twitch.

Your brain literally can't let go of incomplete tasks.

And smart designers use this to their advantage.

Credits: @jimkwik
Look at @LinkedIn's profile strength meter:

"Your profile is 85% complete."

That 15% gap? It's probably KILLING you inside. 💀

You know what happens next - you add that work experience, upload that photo, & write that bio.

LinkedIn knows exactly what they're doing. Image
Read 13 tweets
Jun 12
Look at these 2 UIs.

One of them will 100% outperform the other for 1 key reason:

The Von Restorff Effect.

Here's EVERYTHING you need to know about this psychological trick (and how to use it for your own products to increase conversions): Image
The Von Restorff Effect is basically a fancy way of saying "make it pop."

In design terms: make one thing visually different → people notice it more.

But here's the thing most designers get wrong:

Making something stand out is only valuable if it drives actual results.

Otherwise, it's just noise.Image
Examples include bold buttons, colorful CTAs & standout prices.

@NotionHQ nails it: everything’s grayscale, so colored tags pop.

And that pop isn’t just pretty, it’s practical.

Color = instant organization.
Smart contrast = better memory. Image
Read 13 tweets
Jun 7
I'm obsessed with design psychology.

After 10 years of building products, I've discovered a UI/UX secret:

Dark Mode makes apps harder to use.

Here's why we're all getting Dark Mode wrong, how to use it properly, and what @Apple knew all along: Image
Here's an unexpected fact:

Studies show dark text on light backgrounds is 26% more readable.

The Nielsen Norman Group found reading speed decreases by nearly 10% with white text on black.

Yet every designer acts like dark mode is the holy grail of UX.
Now here's what blew my mind...

Literally half of the world has astigmatism.

That glow you see on white-on-black text? It’s not in your head. It’s called halation.

The letters blur. Eyes strain. Comprehension drops.

But it looks so premium, right? Image
Read 10 tweets
May 31
Look at these UIs.

One of them will 100% outperform the other for 1 key reason:

Hick's Law.

Here's EVERYTHING you need to know about this psychological trick (and how to use it for your own products to increase conversions): Image
Image
Hick's Law states:

The more options you give users, the longer they take to make a decision.

Here's the fancy formula: T = b × log₂ (n + 1)

In plain English: More choices = exponentially more brain processing time.
When I started designing, I thought cramming every possible feature would impress clients.

Spoiler:

This performed terribly when it came to conversion.

So how do we balance features & usability?
Read 12 tweets
May 25
I LOVE design psychology.

Here are 9 sneaky psychological principles your favorite apps use to keep you hooked:

1. The IKEA Effect Image
Image
@NotionHQ is a master of the IKEA effect:

You fall in love with their product because you build it yourself.

When you create your own workspace from scratch, you value it more.

It's like IKEA furniture - you'll defend that wobbly shelf because you assembled it with your own hands...
2. Jakob's Law

Users spend most of their time on other sites and apps, so they expect yours to work the same way.

This is why @Apple never reinvents navigation patterns. They take what's already in your muscle memory and make it better.
Read 12 tweets
May 15
A hill I'm willing to die on:

Spotify's UI & UX will never be defeated.

With 678+ million users, there's a reason it dominates music apps.

Let me break down why its design is so good (and what you can steal from it): Image
1. The navigation is stupid simple:

• Home
• Search
• Your Library

That's it. NEVER more than 2 taps from anything.

While most apps keep adding useless features to their bottom navigator, @Spotify understood that less is more.
2. The mini-player

It sits at the bottom - always there but never in the way.

The gesture to expand/minimize it feels SO natural you forget it's designed. It just becomes muscle memory.

This is what great UX is about - when you stop noticing it exists.
Read 16 tweets

Did Thread Reader help you today?

Support us! We are indie developers!


This site is made by just two indie developers on a laptop doing marketing, support and development! Read more about the story.

Become a Premium Member ($3/month or $30/year) and get exclusive features!

Become Premium

Don't want to be a Premium member but still want to support us?

Make a small donation by buying us coffee ($5) or help with server cost ($10)

Donate via Paypal

Or Donate anonymously using crypto!

Ethereum

0xfe58350B80634f60Fa6Dc149a72b4DFbc17D341E copy

Bitcoin

3ATGMxNzCUFzxpMCHL5sWSt4DVtS8UqXpi copy

Thank you for your support!

Follow Us!

:(