Illustration by David Plunkert, via The New York Times

A bat and a ball cost $1.10 in total. The bat costs $1 more than the ball. How much does the ball cost?

Wait for it, you should feel a gnawing feeling churning in your stomach right about now. Let me guess, was the first answer that came to your mind $ 0.10 cents?

What if I told you that answer was wrong (you can find the right answer here), and that in reality if you had taken a moment to pause and reflect on it for a few seconds longer, you would have easily arrived at the right answer.

The question is highly effective in revealing what has been studied for ages and increasingly gained prominence due to breakthroughs in the field of behavioural economics, and popular works such as “Predictably Irrational” by Dan Ariely, “Thinking, Fast and Slow” by Daniel Kahneman, and “Nudge” by Richard Thaler and Cass Sunstein. The theory breaks down the idea that human beings have essentially two modes of processing information. In technical terms, they might be referred to as System I and System II, but I really liked the way author Dan Gardner described them in his book “Risk” by referring to them as “gut” and “head”.

Now, there’s certainly no shortage of cultural references that highlight our own intuitive knowledge of the matter. More than once, you’ve probably had a moment where you said, “I feel it in my gut,” or “follow your gut”, then of course there’s “use your head” and “look before you leap”.

Here’s a short description of how they work:


  • Automatic
  • Fast
  • Effortless
  • Heuristic-based (relies on mental “shortcuts”)
  • Intuitive


  • Controlled
  • Slow
  • Effortful
  • Rule-based
  • Reason

I got exposed to idea initially working as a Research Assistant for the majority of my undergrad for two marketing professors who specialized in consumer behaviour. But recently as I started reading the designing for web usability Bible “Don’t Make Me Think” by Steve Krug, I thought it’d be neat to try the relate the two fields of cognitive decision-making and web design together.

Krug defines his philosophy behind the rule “Don’t make me think!” as “…as far as is humanly possible, when I look at a Web page it should be self-evident. Obvious. Self-explanatory. I should be able to “get it” – what it is and how to use it – without expending any effort thinking about it”.

Reading just his initial chapter my mind started trying to mash concepts together from my past as a research assistant and my present as a content strategist for a user experience agency, and the conclusion I came to is that fundamentally all design should be directed at the “gut”.

The reason being quite simple, people have ample alternatives and very little time. So if even for a moment they have to get their “head” to kick in to help them accomplish their goal such as figuring out how to get to check-out when trying to purchase a product online, where the search bar is, or what that button actually means, you can almost guarantee the back-button to be pressed immediately.

It’s not so much of a matter of if we’re too lazy to think, but more so the fact that we’re cognitive misers. This theory refers to the fact that we’re bombarded with far more information than we could ever use and so naturally default to our mental shortcuts which could be anything from our own rules of thumbs (ex. can’t purchase that item, back to Google), preconceived stereotypes (ex. If they can’t design a site, they’re probably too sketchy), all the way to larger cultural and societal norms and understandings (ex. everything on the web needs to be fast, we live in a time of instant information).

So the next time you’re designing something ask yourself just how involved a user’s “head” is and refine the interface until you get that “gut approval”, trust me it’ll be well worth putting in the effort so that the end user never has to.