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UX and Human Factors: How to use psychology to empower the user

What is Human Factors Psychology?


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Victoria Claypoole

3 years ago | 10 min read

This article first appeared in the UX:Collective: https://uxdesign.cc/ux-and-human-factors-9866337a61a7

User Experience (UX) is an extensive interdisciplinary field that encompasses many aspects of design and engineering. When you hear the term “UX,” you may relate it only to applications and software, but it’s actually much bigger than that! The principles of UX have been applied to a wide range of topics, from customer service to retail store layouts.

UX is all about empathizing with people, anticipating their needs, and creating solutions that lead them towards their end goals. By putting people first, we ensure that whatever we’ve spent our time and money making will be useful and enjoyable to those who use it.

There are tons of principles, ideas, and philosophies designers use when developing and implementing their designs. But! Did you know, you can actually use psychology to enhance your UX and truly empower your end-users? In fact, the father of UX (Don Norman), is a well-known cognitive psychologist! In this post, we’ll discuss a lesser-known branch of psychology — Human Factors — and how you can use it every day within your designs.

Wait…isn’t psychology just diagnosing people?

No! Psychology is the science of mind and behavior, and while that does include diagnosing mental health disorders, it also encompasses learning theory, groupthink, and memory — among a whole host of other areas of interest (McLeod, 2019).

Though Psychology as a formal discipline is relatively young — it’s only been around for 150 years or so after all — it can actually be traced all the way back to the 4th century BC where Hippocrates theorized that mental disorders had physical causes — instead of you know, demonic ones.

As a general rule of thumb, the field of Psychology seeks to describe behavior and cognition, explain their occurrence, predict future instances of such occurrences, and change them in a beneficial manner.

Take for example, house training a dog. First, we first describe what the behavior is (dog urinating in the house), understand and explain it (well, the dog has to pee), predict when it will occur again (typically based on the size of the dog, age, water intake, etc.), and then finally- using learning sciences (like operant conditioning; see: here for more)- train the dog not to go potty in the house. Anyone who has trained a dog — or even potty-trained a child — is familiar with this process.

This should strike a chord, as UX also has similar goals — UX designers first want to describe and understand (often through task analysis) their users’ actions, thoughts, and emotions. With this knowledge, UX designers seek to explain and predict things about their users so that they can better match their designs to users’ abilities and expectations, thereby enhancing the user experience.

For example, we may notice that some users always make the same error when filling out a web page — similar to psychology, we probably first describe what’s going on (people keep missing one of the required fields), explain why it’s happening (they miss the visual cue telling them it’s required), predict when it will happen again (especially when multi-tasking), and then change the design to improve the behavior (maybe by making the visual cue more salient by adding a multimodal cue). VOILA! Enhanced UX design!

The aims, goals, and processes of Psychology are not all that different from UX. Afterall, almost all designers know about color theory and Gestalt principles, and readily use them every day. One subdiscipline of Psychology that is particularly relevant to UX is Human Factors, or the scientific discipline of understanding and improving the interactions between humans and systems (HFES, 2020).

So, what is Human Factors Psychology?

As mentioned above, Human Factors Psychology is all about the connection between a person and a “system” (though the term “system” is pretty loose…a system could be a chair, a space shuttle, or even an interdisciplinary team of humans and robots). The field of Human Factors is also known as Ergonomics — this scientific discipline tends to be discussed as “Human Factors” in North American communities and “Ergonomics” in European communities. No matter what you call it, it’s all about understanding and improving the connections between people and the things they use.

Human Factors is ultra-diverse; the field focuses on a whole host of problems — from determining the best shape of office chairs with the aim of reducing lower back strain to improving sustained attention of military radar watchers. Some other areas of concern to Human Factors include workplace arrangement, information presentation/comprehension, and system design (e.g., spatial/visual layouts).

Are you seeing the connections to UX yet? If not, let us reveal a bit more. Human Factors is an amalgamation of several disciplines, including psychology, engineering, interaction design, and — yep, you’ve guessed it — user experience. If you’ve ever re-imagined something to be more efficient, or reduce errors made by humans, or even enhance the safety of something, then you’ve actually already practiced Human Factors (you just didn’t know it!).

Let’s use it!

So, how can we actively use the best principles of Human Factors Psychology to enhance our designs, improve the systems our users work with, and ultimately empower our users?

Here are top three Human Factors principles we use every day in our designs:

1. Mental Models

Mental models represent explanations of users’ thoughts and understandings.. they constitute what a user believes to be true about a given system. This is the understanding users tap to reason about how to use your system.

Mental models encompass the relationship between the function of your system and the user’s perceptions of their actions and consequences when using the system. For example… when I flip this switch up… something will turn on.

Understanding mental models is important because they provide insight into how users perceive, categorize, and comprehend information related to a system’s functionality. These mental models can be readily uncovered through card sorting… our favorite method… as well as user interviews, surveys, and review of competitive products, especially popular ones, so you can infer what users’ expectations may be on how similar systems work.

When designing a system, we should design with the users’ mental models in mind and ensure that our visual representation of the system’s functions matches the user’s mental model.

For example, let’s say we are designing a system that assists an Army vehicle operator as they complete a maintenance checklist.

The vehicle operator has a standard naming convention for categorizing maintenance issues that they use every day; because we are designing our system for these particular users, we should incorporate their naming convention, a critical element of their existing mental model, into our system design.

If we fail to consider users’ existing mental models in our designs, the result will be a mismatch between a user’s beliefs regarding how a system works and the way it actually does in fact work.

And what is the outcome of that? You guessed it… user frustration, no-buy decisions, adopting other systems, and the list of unwanted consequences goes on and on. When trying to determine a user’s mental model one common no, no… do not assume your mental model as a designer is the same as those of your target users.

Since each individual’s mental model will be unique to their experiences, expect that some users may not readily understand certain things that seem absolutely intuitive to you and even other users.

So, as designers, our challenge is to help users evolve and expand their mental models as they use our systems and hopefully in a not too frustrating manner. To achieve a smooth transition, try to introduce new UX elements sparingly and provide hints to support understanding.

Example of a Mental Model used within the Design of an Operational Support Tool for Army Vehicle Maintenance

2. Cognitive Load

There are many different types of memory (long, short, working), and they all function differently. When we are actively engaged with a system, we are typically using our working memory — or information/memories we are only using temporarily.

Working memory is limited in capacity, meaning we can only do so much at one time. Cognitive load is related to our working memory, and it refers to the mental effort required to learn something new based on the amount of information a person must process and/or use at one time.

Think of working memory as the act of juggling and cognitive load as the balls to be juggled. Juggling two balls is pretty easy…three balls is still fairly easy… four is a bit more difficult, but still doable…five is getting hard and mistakes are probably being made…10 balls to juggle is too much and all the balls come crashing down.

Our working memory is just like that — too much information to handle and our cognitive load reaches its limit, so we start to make errors. So how does this relate to UX?

Well, designs that pose high cognitive load on users… that is, require high levels of mental processing power to learn to use and operate the system… impose high barriers to adoption. In our designs we have to strike the right balance between presenting too much information and presenting the right information at the right time.

If we present too much information all at once, we will likely overwhelm our users and they will make errors, or even worse disengage and abandon our system. If we go too minimal and hide/nest important information, users may get frustrated or bored.

To achieve a performance empowering balance, designers can build on existing mental models, avoid visual clutter, and support short-term memory by displaying smart default values that guide user input, providing scaffolding (i.e., progressive disclosure of more features/functionality), using breadcrumbs, using context-sensitive help and hints… you get the picture.

It’s important that we understand our user’s cognitive load when using our systems and then design our information architecture appropriately — think about what the overall goal of using your system is, what information the system should provide to help users reach that goal, and what memories / expectations they are using from their personal experience (a.k.a. their mental models) to help them achieve their goal.

By understanding these aspects of user interaction, we can be sure not to overwhelm our users’ cognitive load and enhance their user experience.

3. Consistency

I know what you may be thinking…Consistency? But that’s a tried-and-true UX design principle! Which is correct, but it’s important to Human Factors as well. Here’s a few ways that design consistency and Human Factors are entangled. So, remember that users bring their mental models with them when they start to use your system.

They also evolve those mental models as they interact with your specific UX design. So if your design happens to have inconsistencies, guess what? Users will constantly be flip-flopping their mental models, or belief in how the system works, each time they hit up against an inconsistency.

The result… a complete lack of understanding and instigation of superstitions regarding how your system works… can you imagine anything more frustrating? Those inconsistencies will prevent users from being able to transfer what they learned from one aspect of your design to another. Like a toddler who is timid to take her first steps… your users will become gun-shy to try-out new functionality.

Consistency and cognitive load are also intertwined. If users encounter different UX patterns than what they have previously engaged with, it will force them to pause and try to understand the new patterns.

The cognitive demand imposed by this reasoning regarding UX inconsistencies hinders usability, as designs that are imbued with visual, functional, or external (other related products) inconsistencies are confusing, complicated to learn and use, and impede development of a robust mental model.

These issues impose a heavy cognitive load on users not only when learning to use your system but also each time they engage with the system. Image if every time you went to unlock your front door you had to visually look at the keyhole because it randomly changed its orientation… frustration would abound! Such inconsistent interaction forces users to be hypervigilant, always trying to figure out how your system works.

By ensuring your designs are consistent visually and behaviorally, users can relax a bit as they do not have to devote high levels of brain power to decode your UX schemes.

Further, as UX designs start to g0 heavily cross-platform (e.g., tablet, AR headset, VR headset, etc.), maintaining consistency across these platforms is going to be tricky but super important.

Example of Design Consistency between Tablet- and Augmented Reality-Based Versions of an Operational Support Tool

Conclusions

UX designers can leverage the principles of Human Factors Psychology to empower their end users.

By ensuring consistency within our UX designs, leveraging our user’s mental models, and reducing cognitive load, we can improve our users’ performance, reduce their confusion, and truly empower them in their everyday lives!

For more information on Human Factors and all it entails, check out the Human Factors and Ergonomics Society’s website here. For other Human Factors design principles, see this recent AdobeXD blog here and this one from UX Collective here.

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Victoria Claypoole

Dr. Victoria L. Claypoole is a Human Factors and Cognitive Psychologist with an extensive background in Product Design.


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