A brief guide to the theories that shape human-centred design

The basic principle of human-centred design (HCD) is really simple. It’s all about understanding what people need from a product so we can make it easy to use. 

But do you know about the fascinating theories that go into perfecting HCD? 

HCD isn’t just a passing fad. It’s based on decades of research and theory, drawn from different fields such as psychology, linguistics, computer science and anthropology. 

Over the years, we’ve distilled these theories into a tried and trusted methodology that helps us:

• research what people need from an online product
• design the best way to help them get it

In this article I’ll provide a brief history of the practical theories that guide our work as content designers, and examples of using them to get the best possible results.

Using ethnography to understand people’s needs 

Let’s start at the beginning of the design process. Did you know we draw on ethnography to research what people need from a product or service?

Ethnography is basically a way of understanding people by studying their habits…in extremely painstaking fashion! 

Ethnographic research involves studying the:

• language people speak
• culture they inhabit
• way they view the world  

This is done through a mix of cultural immersion, interviews and behavioural observation. Using this approach helps you get the type of precious qualitative data that you can’t get from surveys.

For the purposes of human-centred design, we’ve distilled ethnographic methods into an approach that allows us to gain the greatest possible empathy with people. Empathy is vital to understanding what people need and designing products and services that are usable.

Using cognitive psychology to design better services

Once we understand who we’re designing for, it’s all about how we design for them. 

This is where cognitive psychology comes in. 

Cognitive psychology is the science of how people think. It focuses on:

• memory
• attention
• concentration
• learning
• patterning

In the mid-20th century, cognitive psychologists developed the idea that human decision-making can be tested, understood and predicted.

In the 1970s, this would lead to a revolution in the way companies thought about designing their products. The idea was: if we can test-predict what people need and how they’ll behave, then we can use this to design easier-to-use (and more desirable) products.

Adapting technology to human minds

Then came computer science. In the 1970s and 80s, cognitive psychologists such as Don Norman pushed the idea that computer technology should be adapted to human minds, and not the other way round.

Norman argued that: “People are so adaptable that they are capable of shouldering the entire burden of accommodation to an artefact, but skilful designers make large parts of this burden vanish by adapting the artefact to the users.”

Norman’s theories would have a huge influence on how user interfaces were designed going into the 21st century. This would be the basis of what we now call “user experience (UX) design”. 

The goal of UX design was simple: to deliver the smoothest possible journey towards the completion of every task.

“The best designs are those that disappear. They are so well integrated into our lives that we don’t even notice them.” Don Norman.

How Hick’s Law helps improve user experiences 

One of the key elements of cognitive psychology that we use in human-centred design is Hick’s Law. 

Hick’s Law is a theory developed by William Edmund Hick and Ray Hyman in the 1960s. It says that the time people take to make a decision increases with the number and complexity of choices they face.

You can improve your content right now by presenting information in a way that people can quickly grasp and process. Otherwise, they may give up on the task. 

It’s why we try to streamline an interface and reduce brain overload by using plain language and a simple, intuitive lay-out. But we also need to be careful to avoid over-simplifying information to the point of abstraction.

It takes a lot of work and repeated iterations. But, thanks to what we’ve learned from cognitive theories such as Hick’s Law, we can design services that are a pleasure, not a chore, to interact with. 

“If you think good design is expensive, you should look at the cost of bad design.” Dr. Ralph Speth.

Find out how to create a business case for human-centred design.

Eye-tracking studies in design

Another important element in both cognitive psychology and human-centred design is the use of eye-tracking. This is technology that allows us to observe where people focus their attention when they interact with a product. 

The first eye-tracking technology was first developed as far back as 1908 by the psychologist Edmund Huey. Originally used to understand how people respond to books, posters and films, it quickly developed into a useful tool in market research. 

In the 1980s, increasingly powerful computers were able to do eye tracking in real time. This made it possible to use video-based eye trackers to study human-computer interaction.

Eye-tracking was first applied to the internet in the late 1990s. Since then, it’s played an increasingly important role in the way we do digital design.

Using heat maps to track people’s habits

For example, take heat maps. We often use these in usability testing. A heat map is a graphic that uses a colour-coded system to show where people’s attention is going as they interact with content. 

What people do between clicks, as well as what captures their attention, or causes confusion, can tell us a lot about whether a piece of content works. 

Using plain English to get the message across 

Now let’s consider the process of writing and editing good content. The goal of our work as content designers is to create words that have an impact. That impact could be galvanising people to take action, or helping them to do a task or understand something complex. 

Key to our philosophy is using plain language that everyone can understand. 

The benefits of using clear, clipped prose have long been clear to great writers such as Ernest Hemingway, George Eliott or George Orwell. In the early 20th century, marketing gurus also understood the power of simple, incisive text.

But it wasn’t until the 1970s that a movement came along demanding a revolution in the use of plain English for public services.

How the “Plain English” movement developed in the UK

In 1979, a group of academics called the Plain English Campaign tore up official government documents in Parliament Square, announcing their commitment to battle “gobbledegook, jargon and legalese”.

They believed that everything from legal texts to legislative documents should be written in jargon-free language that anyone could understand. 

Nearly half a century later, as more and more people become reliant on digital services, the need for plain language is greater than ever. As the poet Cicero said: “Every word that is unnecessary only pours over the side of a brimming mind.”

Start with accessibility when you create content.

Conclusion: why human-centred design matters

The ingredients of good design are many and varied. It’s not just about good writing skills, with a bit of research and half-arsed marketing theories thrown in. 

Good design is understanding who people are and how we can best serve their needs, based on the most influential theories of our times.

That’s why we call it “human-centred” design.

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