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.

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More from @DenisJeliazkov

Sep 12
I'm obsessed with design.

Over the last 6 years, I've analysed every Travel App on the market.

Here are 11 of the best (and worst) Travel Apps & what you can learn from their UI/UX(& the market gaps everyone's missing):

1. @Airbnb Image
THE BEST

These guys get it.

Real-time search that doesn't make you want to punch your screen. Map, pricing, availability - boom, all in one view.

No dead ends. No "sorry, not available" after 10 clicks.

The filters actually feel like filters, not a damn spreadsheet.
Image
2. @Flighty

This app was clearly built by someone who LOVES planes. Like, really loves them.

Shows you everything:

• Your actual aircraft type
• Turbulence predictions
• Weather at arrival

Even has this sick passport screen that makes you feel like James Bond.
Image
Read 17 tweets
Aug 14
I'm a product designer.

I've definitely spent 1000+ hours analyzing tiny UI details.

My current obsession is @Apple's Glassmorphism.

Here's the insane technical breakdown nobody talks about (and how you can use this trend effectively in your products): Image
The OG glassmorphism started as a trend.

Designers threw in 20px blur and 10% white, called it “frosted UI.”

Yes it was pretty, but it sure as hell wasn't the most functional.
Too much contrast, bad layering, zero depth logic.

Then @Apple said: “Let’s fix it.”
Try this:

Open your iPhone. Look at the blur.

Now move something colourful behind it.

The blur CHANGES COLOR. Not just tints - it literally pulls the vibrancy through.

That's not how CSS blur works...
Read 12 tweets
Aug 9
Look at these 2 UIs.

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

Peak-End Rule.

Here's how this psychological principle works & how to use it in your products: Image
As the name suggests, this rule states that your users don't remember everything about your app.

They only remember two things:

1. The most intense moment (peak)
2. How it Ends

That's it. The rest is forgotten by their brain.

(Credits: @UXChrisNguyen)
What this essentially means is that you can literally have 20 mediocre screens...

But if you nail the peak & end?

Users will still love your product. (not saying you intentionally make it mediocre lol)

Let me show you who's doing this right (and who's f*cking it up): Image
Read 14 tweets
Aug 2
I'm a design addict.

I've tested pretty much every music app on the market — and these 5 are worth studying.

Here's a UI/UX breakdown of the 5 most popular music apps (and which features product designers & founders can steal from them): Image
1. @SPOTIFY:

The Social Media of Music. They turned music into @Instagram.

Wrapped = yearly flex
Shared playlists = social currency
Algorithm = scary good at predicting vibes

But here's what they don't tell you:
Spotify's UI is actually manipulative.

Fun fact: those "Made for You" playlists are pushing artists who pay less royalties.

The shuffle isn't random either. It's designed to keep you hooked.

Still the best UX though. Image
Read 14 tweets
Jul 31
Look at these 2 UIs.

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

Fitts's Law.

Here's how this psychological principle works & how to use it in your products: Image
Fitts’s Law in 3 seconds:

The closer & bigger the target, the faster & easier it is to hit.

You already know this in your bones. It’s why:

• You miss the “close” button & accidentally open an ad
• You try to tap “save” but hit “delete” instead

(credits: anirudhux)
Apps that nail Fitts’s Law:

1. @Google – Massive search bar. Big buttons. Right in your face. Zero confusion.

2. @Spotify (Desktop) – Right-click menus where your mouse already is. Huge targets. Efficient AF. Image
Image
Read 12 tweets
Jul 26
As a product designer, here are 8 of my favourite designers on X:

(with a breakdown of their best shots) 🧵

1. @raunofreiberg - show me a more interactive website, I'll wait
2. @msenyil

UI that feels alive - even when it’s a throwback.

His Atari on-chain project with @Coinbase.

A perfect mix of nostalgia and modern UX discipline, down to the tiniest button label. Image
3. @tomkoszyk

Nobody makes “boring apps” look this good.

This portfolio dashboard - perfect spacing, clean grid, and numbers that feel important without being loud. Image
Read 10 tweets

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