Be usable, not consistent, not uniform

Several blue, white and black circular icons, and one orange and black star icon

There is a harmful myth that pervades design decision-making. It’s an assumption that, on the surface, seems so sensible that few people ever question it. And yet when applied carelessly it can cause real harm.


It is so often seen as a slam-dunk argument in favour of an initiative. But many people pursuing consistency don’t stop to ask a simple question:

Consistent with what?

Consistency can be a great thing if it makes a design more usable. But if you don’t know what you want to a design to be consistent with — and why — then consistency risks confusing your users.

Consistency is more about organisational ego than users

To many stakeholders, pursuing consistency feels like decision-making. But it is often a sign of indecision.

As Jared Spool wrote:

Why do we gravitate to consistency? Because it’s easier to think about. You don’t actually have to know anything about your users to talk about making things consistent. You only have to know about your design, which most designers are quite familiar with.

Initiatives pursuing consistency often end up being more about organisational ego and brand than about what’s best for users.

Consistency can make your services harder to distinguish

Incidents like Google’s redesign of many of its app icons to use consistent colours and shapes rightly attract derision.

These icons probably looked great in internal meetings talking about how great consistency is. But Google seemingly failed to consider that making their icons look so consistent made it much harder for users to distinguish between, for example, Google Drive and Google Calendar.

Google are far from the only offenders. Microsoft also make their Office 365 products so difficult to tell apart by their icons.

These icons use a consistent visual language, but at least many of them icons use different colours and letters to be distinct. But what were Microsoft thinking when they designed the icons for SharePoint and Sway?

Sharepoint and Sway icons - both white S glyphs against a teal background

Not only do they have the same letter, they also have the same colour. I am constantly getting these two icons confused. That is a big problem for me because I need to use SharePoint quite a lot at work, but I have wanted to use Sway precisely zero times.

(Weirdly, even though these icons look so confusingly similar, they aren’t actually consistent! When comparing them side-by-side it is possible to see that the S glyphs are slightly different sizes.)

These are examples of consistency that cause a bit of wasted time and frustration while users get confused between services. But there are cases where consistency causes harm.

Consistency can cause real harm

A can of Fly & Insect Killer next to a can of Canola Cooking Spray - both with similar black-on-yellow designs

Original image by moojj on Imgur

This idea is neatly demonstrated by a viral image that shows two aerosol cans with identical branding and design. One is for cooking spray. But the other is for insect killer.

These designs probably look great on the company’s product lineup for their consistency. They are less great if you accidentally use the insect killer instead of the cooking spray.

Maybe that’s an unlikely scenario. But it does demonstrate how consistency might work against users.

Sometimes consistency can cause so much harm that it risks excluding people.

Consistency can exclude vulnerable people from accessing justice

The UK government’s design principles are rightly hailed as exemplars for designers to take inspiration from. One of the most famous principles is: “Be consistent, not uniform“.

We should use the same language and the same design patterns wherever possible. This helps people get familiar with our services, but when this isn’t possible we should make sure our approach is consistent.

However, there are instances where making every government service look consistent causes harm and exclusion.

Some online court services have adopted the Gov.UK design system. This means these court websites look consistent with many other UK government websites. This is thought by some to be a good idea because it increases consistency.

However, this is one example where consistency can serve to confuse some of society’s most vulnerable. That’s because it undermines the constitutional independence of the courts from the government.

This becomes a major problem in the case where people using the justice system are facing another part of the state. One example is the Social Security and Child Support Tribunal, which handles appeals against decisions about social security.

Citizens attempting to appeal decisions about, for example, carer’s allowance or disability living allowance, are presented with a website design that looks identical to the government department they wish to appeal against. This can make people reluctant to trust the service or use it at all.

A report by the law reform charity Justice into digital exclusion in the justice system (see pages 69–70) noted the following:

We were informed by [HM Courts and Tribunals Service] that the private beta phase of the Social Security Tribunal has had to put a note on its first page to reassure users that the tribunal is independent of government.

The charity continues to campaign for online justice services to have a design that is distinct from the rest of Gov.UK, to minimise digital exclusion in the justice system.

What we can do instead of focusing only on consistency

In order to best make human-centred services we need to focus on utility and usability ahead of consistency.

This means first ensuring that our services are actually needed by our users. Then we need to understand people’s mental models and ensure our designs fit with those mental models.

Or, as Jared Spool puts it, we need to ask: “Will the user’s current knowledge help them understand how to use what I’m designing?”

We do need to pursue consistency. But that consistency needs to be with people’s understanding — their mental models of how they need to get their thing done. Sometimes that means being inconsistent in other ways, such as visual design.

The consistency you choose to prioritise shows whether you are being human-centred. You need to be consistent with your users’ needs and mental models. If you prioritise other types of consistency, you risk confusing users in favour of your organisation’s ego.

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