How insights from Cognitive Psychology
help to build better websites


11.000.000 bits/ sec

20 Watts



> 95%


How does the brain

"fix" reality?


Which Lead to

Loads and loads of Biases

Pick a number

Let's try this...

1, 2, 3, 4

Who picked 3?

Around 60% does!

Data informed

Usability Testing



Talk to the brain

Use the biases

Title Text


Too much information

Time limitations

What to remember?

Too little information

Too much information

There is just too much information in the world, we have no choice but to filter almost all of it out.

Too little information

The world is very confusing, and we end up only seeing a tiny sliver of it, but we need to make some sense of it in order to survive.


Time limitations

We’re constrained by time and information, and yet we can’t let that paralyze us.

What to remember?

There’s too much information in the universe. We can only afford to keep around the bits that are most likely to prove useful in the future.



Too much information

Time limitations

What to remember?

Too little information

A/B test examples

on several e-commerce websites

Information overload:

Placement (and clarity) of costs

14.5% CR

16.3% CR

12.5% Uplift!

Information overload:

Addons on the product page

15.87% CR

18.23% CR

14.9% Uplift!

Need to act fast:

Direct checkout option

Directly go to checkout

€2.7 - 5.2M extra yearly profit

Information overload:

Why should I buy here?

Old version, on bottom of the page

New version, on top of the page

Conversion uplift: 5.3% (p =0.0361, Power  89,6%)

€278K - €453K extra yearly profit

@guido | | 25% successrate 10% successrate

Unfortunately, not all experiments are a success

Euroflorist: 10-20 concurrent tests

Booking: 1000+ concurrent tests

and then there's experimentation bandwith

Image sources

Noun Project

  • Brain - Sergey Patutin
  • Line Graph - Robbe de Clerck
  • Head brain - Blake Ferguson
  • Website wireframe - KΛPKLΛM
  • Cognitive Bias Codex - John Manoogian III &  Buster Benson



Persuasive E-commerce at Opticon 2018


Persuasive E-commerce at Opticon 2018

Xth iteration of the Persuasive E-commerce presentation I've been giving since 2011. 40 minute version for Opticon London 2018.

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