Creatures of Convention

I remember when I was in grade school, I was baffled by my teacher’s insistence that I spell the word “thief” correctly. What got me puzzled was I spelled it “theif”, yet she recognized it immediately and knew what it was (enough to correct it). Since I had communicated the word I wanted, what was the difference if I spelled it wrong? It wasn’t for many years until I understood the answer to that question.

We are creatures of convention. When something doesn’t match our expectations, we have to stop and spend more cognitive energy making it fit into our world.

Take this sign I stumbled upon at a local Baskin Robbins:

4.8 is the same as 4.80, when talking about decimal numbers. Yet, what does $4.8 mean?

In many contexts, people naturally expect money to be represented a certain way. In the US, the convention of showing two decimal points after the dollar amount is what people expect. Anything else makes people stop and think for a second. (In other parts of the world, a comma (‘,’) commonly is swapped in meaning with the period (‘.’), so 23,480.10 would be represented as 23.480,10.)

When we run into something we don’t expect, it causes us to stop and change our cognitive focus, albeit for just a moment. Typos can have the same effect. While we almost always can deduce the author’s intent, the act of decoding the word stops us from considering the meaning of the sentence and makes us consider the meaning of the word. Only when we’ve done that, can we get back to the sentence.

The extra time it takes slows us down and makes us less efficient. This is why spell checking your content and making sure you’re following conventions people need are important.

(By the way, don’t confuse convention with consistency. A consistent interface may follow common conventions, but it may not. And something that is consistent without being conventional doesn’t help the user, usually. Left navigation, while frequent, is not yet a convention because it just hasn’t been around long enough. That’s why we can say right-side navigation is just as good.)