Interaction design guru Alan Cooper (www.cooper.com) defined this term to describe the mental stretch caused when tools behave in a way that seems unrelated to what you wanted. I find it extremely helpful in illustrating the ever-present anxiety of being a normal web user.
Note: Alan describes this much better in his excellent book "The Inmates are Running the Asylum". Please buy it.
In times gone by, using a tool to do something was a simple affair. e.g. Gather friends > take sticks > make stick pointy > poke mammoth with sticks > repeat until mammoth falls over. The pointy stick is very low in cognitive friction: its purpose and form are directly related. Even if you'd never used a pointy stick before, you could imagine how you could use it simply by looking at it or handling it. If you stick yourself in the leg with it, you understood why you'd been stuck in the leg, and you would learn how to avoid getting stuck in the leg again.
Todays' tools are generally high in cognitive friction: their form and purpose are more often unrelated.
In order to get my microwave to heat some food, I first have to set the length of time to cook for. I can't just press 'Start' and then stop it when I choose. Then, I have to select my power setting. Then I press 'Start'.
On the other hand, when I've finished writing this topic, and wish to shut down my (Windows) computer, what do I press? Yes, the 'Start' button.
There's nothing about my microwave that lets me know how to use it to fulfil my goal of getting food hot. There's nothing about my Windows PC that tells me how to shut it down. You have to work these things out for yourself today, somehow! That's the cause of cognitive friction.
Another effect you notice with cognitive friction is: if something doesn't work, you're made to think it's your fault.
Causes of cognitive friction on the web
Experience teaches us not to trust new sites straightaway. There are so many web sites out there, when we're searching for something, it's likely that this unfamiliar site we're on is the wrong one. If we're on the right site, we're probably on the wrong page.
Think about it. To complete a typical web goal, say booking a hotel ticket, you may have to visit 25 web pages (search engine, follow a link, go back to search engine, follow another link, find right site, navigate to booking section, select dates and room type, check availability, enter all your information, enter your billing information, verify your billing information, confirm your order... Only one of those pages actually books the hotel ticket. Most of the others either completely wrong, or in the way.
I know the web is too big to see. Statistically, I'm almost certainly not on the right page, and anyway the next search engine result is likely to load faster and help me find what I'm after quicker.
Hyperlinks are naturally high in uncertainty. Click one and you could end up anywhere. What's more, click the wrong one and you could accidentally launch an obscene web site, a hundred popup adverts, or pick a virus. (How designers can minimise the uncertainty of hyperlinks)
How do users respond?
The main coping mechanism we use to counter the low trust we have in the web is a manic, impatient behaviour.
- We decide in as little as 1/20 of a second whether a site is appealing or not.
- We scan pages for clues that "You're in the right place"
- We make quick decisions about whether to carry on or go back (It's proven that web users don't read the page and make a valued decision on the best link to follow, but select the first likely-looking option. See Steve Krug's book "Don't Make Me Think" - below - for more excellent insight into this.)
- When searching, we often don't even wait for the page to load, before deciding whether to click back, or follow a link (Note: Principle of putting the most important stuff at the top so it loads and is seen first.)