The Eureka Effect in UX


Dear Reader,

Today I want to tell you the story of Archimedes, possibly the greatest scientist of the classical age.

According to the story, a newly-elected general commissioned a gold crown for the temple.

But after the goldsmith made the crown, rumors circulated that it wasn't pure gold but diluted with cheap silver.

So the general ordered Archimedes to figure out if his crown was pure gold...without damaging the crown in any way.

The task stumped brilliant Archimedes.

He tried everything, but he couldn't find the answer.

If the goldsmith was a thief, he was a smart one because the crown weighed the right amount.

One day, while bathing in a tub, Archimedes had an epiphany.

As he lowered himself into the tub, water seeped out at the same volume as his body.

He realized that he could test the crown with a similar amount of gold to see if the goldsmith stole gold for himself.

If it was part silver as the king suspected, it would displace more water because silver has more volume than gold for the same weight.

He he ran into the night completely naked, screaming, “Eureka!” (I have it!)

The Eureka Effect in UX

What allowed Archimedes to make that discovery?

Inspiration may seem easy when you have it, but when you need it, it's never there.

If you've ever been stuck on a design problem, you know the feeling that Archimedes had before the tub.

How do you work through a UX problem when you can't see the answer?

The breakthrough is called the "eureka effect" or "Aha! moment."

It's a moment where everything shifts into place and immediately makes sense. It's an instantaneous connection of lots of data to form new meaning.

In UX, we have a name for that jolt.

It's called a user insight.

And once you have one, there's no going back.

It's a paradigm-shifting discovery, and it can change your entire organization if you know how to harness the power.

A framework for understanding insights

“I saw this” + “I know this” = insight

It's a very useful way to understand insights.

Let's use it to look at Archimedes' tub example:

I see that an equal volume of water is displaced when I get in the tub
(I saw this)

+ I know that silver has more volume than gold per weight
(I know this)

= "Eureka! I could put the original amount of gold in a tub and test it against the general's crown"
(insight)

This formula is a 1 + 1 = 3 relationship because insights are more than the sum of their parts.

What you saw + know = something completely new.

Insight example in UX

You can use this in UX research as well. Let's take the common occurrence of an abandoned shopping cart in this new formula.

37% of users abandon their shopping carts
(I saw this)

+ I’ve never seen that happen in real life
(I know this)

= There must be something seriously wrong with the checkout flow
(insight)

This equation format helps you understand insights but isn’t compelling as a final format for sharing insights.

So how should you write a user insight?

How to write better user insights

There's not much out there to help you format your insights. There aren't many examples, either.

Everyone talks about presenting insights, but nobody talks about how to actually write an insight.

So I wrote a complete guide:

It comes with a handy template you can use to get started or even use with your team to get everyone on the same page about user insights.

I hope you find it useful!

Jeff Humble
Designer & Co-Founder
The Fountain Institute

P.S. We've got some FREE events coming up in February...


The Fountain Institute

The Fountain Institute is an independent online school that teaches advanced UX & product skills.

Read more from The Fountain Institute
A collage-style image showing two identical women in long dresses near a revolving door, one entering and one stepping away, with abstract starburst shapes behind them.

Why Decisions Feel So Hard Right Nows By Hannah Baker Dear Reader, Over the last few months, I’ve been talking with design and product leaders across very different organizations, large companies, smaller teams, fast-moving environments, and slower ones. And I keep hearing the same thing. Their teams are being asked to make decisions faster than ever, and yet, deciding feels heavier than it used to. Not slower, exactly. Just harder. At first, people often explain this in familiar ways: too...

IBM Watson AI Failure

When Speed Stops Being the Bottleneck by Jeff Humble Dear Reader, Quick question: What happens when the thing that used to take 12 weeks now takes 4 days? I've been watching this play out across the industry, and it's wild. Lots of companies aren't sharing their new speeds, but a few are: Code and Theory (an agency that works with Microsoft and Amazon) is building dashboards in 40 minutes that used to take a week. They report cutting time-to-prototype by 75%. Coinbase reports a 2-5x increase...

Missed a few newsletters last year? Start here. By Hannah Baker Dear Reader, Before we jump into new ideas for the year ahead, we wanted to pause for a moment. If your inbox was anything like ours last year, there’s a good chance you missed a few newsletters. So instead of sending another new idea right away, we put together a curated catch-up, a handful of pieces from 2025 that capture the questions we kept returning to. If you only read a few things from us last year, these are a good place...