It's all about consistency
Do you remember when it was the first time in your life that you opened a door, switched on a light, wore your shoes or nailed something on the wall? I bet that you can’t recall how you knew the way to do it…you just did.
The main reason you can open a door is because all the doors are about the same, their door handles are about the same and you have been taught to grab the door handle and push a piece of wood to enter a room. Before you even touch a door, you knew how to do it by watching people do it - by watching them perform the same series of actions every single time they wanted to get into a room. Donald A. Norman has written a lot more about the psychology of everyday things from 1988, in his book “The design of everyday things”.
Commitment, consistency and motivation affect our ability to reach our goals. Everything we do in every aspect of our life becomes easier once we do it consistently enough for it to become a habit. Think about it…maybe we are alive because of consistency. People will keep falling the stairs if someone decided that steps shouldn’t be of equal height, or they will crash if someone decided that traffic lights don’t have to be consistent everywhere. So, in some aspects, consistency is life-saving.
Similarly in computers, without knowing why, you know that when you want to open a folder, you click on it. When you see a red exclamation mark you know that something went wrong or if you click a button something happens: you go to another page, you submit a form or you perform another action. You know it because all operating systems use the same rules to maintain consistency and so as to be easily usable.
As for designing interfaces, consistency is crucial for building improved user experience. By maintaining consistency, not only you create a usable interface for users, but you ‘educate’ them on how to use your product.
Watching the sandwich icon, we instinctively relate it to the menu and by clicking the bell icon, we expect to see notifications. Most websites have maintained this consistency and we, as users, are educated to use them in a certain way. Similarly, links are supposed to be the same colour everywhere in the website, reviews are displayed the same way and breadcrumb is in the same position in every page.
As companies and organisations design for the larger user experience, it’s important to consider consistency across all channels. Each interaction is part of the overall user experience with a company. If the user experience isn’t consistent across channels, users will question the organisation’s credibility. So, maintaining consistency builds user experience and improves trust with the organisation.
To sum things up, users have their own unique minds and adapting to each individual personality is an impossible task. Maintaining consistency is about creating one solution for all. An inconsistent UX requires the user to repeatedly allocate thinking to how to use the interface. On a UX with good consistency, the user will spend a reasonable amount of time learning the interface and once they learn it, the use of the interface controls require only a small amount of active thinking.