Steve Krug’s “Don’t Make Me Think” was the first book I read on usability, back in 2010.

The central tenet – don’t make users think – concisely encapsulates UX.

‘Thinking’ is a barrier to users completing their tasks quickly.

Today, my local Sainsbury’s shop made me think. After I finished scanning my items at a self-service checkout and paying by card, I was confronted by the following screen.

UX at Sainsbury's: stop and think

UX at a Sainsbury’s self-service checkout: I was made to stop and think

My instinct was that something had gone wrong. Perhaps I’d entered my PIN incorrectly, or my card had been declined.

As it transpired, there was nothing amiss. I was free to remove my card, take my shopping and head home to cook some curry.

I had assumed (and I’m guessing I’m not the only one) that the big red encircled exclamation mark indicated an error. Put ‘error icon’ into Google images and you’ll get a bunch of red circles and a fair few exclamation marks.

By breaking convention, the screen had made me think, unnecessarily.

Alternative approach - better UX?

Alternative approach – a clearer indication of success

An alternative for Sainsbury’s would be to ensure the screen adheres to basic and long-established conventions about successful interactions. Specifically, the colour green and a big tick.

Wording that more clearly indicates system status – by specifying explicitly that payment has been successful – would be good, too.

Otherwise (I’ll add, just for balance), the often-maligned self-service experience was excellent.

Good UX is like a good football referee – you shouldn’t notice it’s there. Making users unnecessarily stop and think about their interactions slows them down, which can cause frustration and dissatisfaction.

The less we make users think, the better their experience.