Human Factors

What is Human Factors?

Summary: What is Human Factors and why should you care? Human Factors is an applied research discipline focused on designing better systems by leveraging knowledge regarding human capabilities and limitations. If a human being interacts with it, Human Factors provides the skills and knowledge to make sure that interaction is safe, efficient, and enjoyable!

By Greg Hallihan on May 20, 2021

Let’s Start with the Fox and the Stork

Victorian style image of the fox and the stork fable.
Fox and the Stork (Original Source Unknown)

If you really want to understand Human Factors, it helps to familiarize yourself with Aesop’s classic story about two passive aggressive animal friends, the Fox and the Stork. At least it might… so bear with me.

One day, the Fox invites the Stork over for dinner and serves soup (a bisque ) in a flat, shallow dish. The Stork, with his long pointed beak struggles to lick it up and hardly eats, while the Fox has no problem lapping it up. The Fox being a bit of a jerk asks the stork why he doesn’t like the soup, but he knows what he did.

Some time later, the Stork invites the Fox over for dinner and serves his own soup, but he serves it in a long, narrow vase. The Fox, with his shorter, broader snout, can’t really get into the vase and hardly eats. The Stork being a rather cheeky fellow asks the Fox why he didn’t like the soup – classic Stork.

Aesop would have you believe this story is a lesson in the golden rule; do unto others as you’d have them do unto you. But it’s really one of the earliest documented examples of the value of Human Factors, told through the antics of two anthropomorphized animal frenemies. Let me elaborate.

The Fox and Stork have specific anatomical characteristics (i.e., a long bill or a short snout) and the soup delivery system has specific design characteristics (i.e., the shallow dish or deep vase). The interaction of these two sets of characteristics directly affect both the Fox and Stork’s individual performances when trying to accomplish their task (i.e., drink soup).

If you understand the capabilities and limitations of the people that are using the system you can design it to be easier for them to use successfully. While this might sound like common sense, the profession of Human Factors exists because systems are often designed with little consideration for the people that end up using them.

Human Factors

Human Factors is an applied science focused on the application of knowledge regarding human capabilities and limitations to the design of better technologies, environments or processes. Human Factors specialists use knowledge of human psychology and physiology to identify opportunities to design safer, more efficient and more satisfying systems.

Human Factors can be applied in almost any domain that involves human beings, the Human Factors and Ergonomics Society has 26 technical groups from Aerospace and Ergonomics to Healthcare and Product Design. Whatever the industry, a human factors specialist evaluates a system of interest to describe how its output is affected by its interacting components. The outputs of interest are scoped relative to human performance and the components are broken down into design characteristics and human characteristics. Think about it with the following ‘formula’:

A formulaic diagram explaining What is Human Factors. The interaction of system characteristics and human characteristics influence performance.
The Human Factors ‘Formula’

Performance (e.g., how quickly soup can be consumed) is a function of the interaction between design characteristics (e.g., the shape of the dish) and human characteristics (e.g., the shape of the mouth). A Human Factors specialist works with project stakeholders to define relevant performance metrics, like task completion times or self-reported satisfaction, and characterize the interaction of relevant design characteristics and human characteristics. When there is a mismatch between how the system is designed (i.e., design characteristics) and how the users of the system are designed (i.e., human characteristics) the system will underperform.

A Human Factors specialist identifies opportunities to design or re-design a system, such that it works with the capabilities of the people using it, and accommodates their limitations. These opportunities can vary from high level policies (e.g., occupational health and safety guidelines for repetitive lifting tasks) to detailed design recommendations (e.g., minimum font sizes for a computer interface). Not surprisingly, it is a lot easier to change the design of the system than it is to try and change the design of the person using it. However, all too often we expect people to adapt themselves to the use of poorly designed systems and fail to incorporate their capabilities and limitations into the design process.

A Human Factors Example

Imagine you are designing a new website and want to make sure it’s easy for people to read your online content, so you get a Human Factors (HF) specialist to evaluate it. The Human Factors specialist might break down your system (i.e., the website and it’s content) like this:

Evaluating Performance

You want to make sure it is easy for people to read your website, so the evaluation will likely focus on things like legibility, readability and comprehension. This could involve primary research to collect data from people who actually read your content, like self-reported satisfaction (e.g., on a scale of 1-7 how easy did they find it to read), comprehension tests (e.g., after someone reads your website can they accurately describe what you do) or physiological measures like an eye-movements (e.g., how do people’s eyes scan your content).

Alternatively, it could involve secondary research or an inspection based approach (e.g., does your website comply with best practices in usable and accessible design). In this case, it’s assumed that performance will improve when adhering these design standards because they’ve been demonstrated to improve usability in other comparable contexts.

Identifying System Characteristics to Re-Design

When the Human Factors specialist looks at the website they’ll start evaluating system characteristics (i.e., the design of the site). The identification of opportunities to improve the design will be influenced by the evaluation methodology. For example, a Heuristic Evaluation is guided by a pre-determined list of design best-practices with a broad focus on the entire user-interface, whereas a CLOZE Test would focus specifically on evaluating the terminology being used with actual users of the site.

As it relates to content readability, regardless of the approach used they will likely have recommendations for things like the font type and size, contrast ratios between the text and the background, the terminology and reading level used, and/or the content layout. Take a look at the example below and consider how differences in the design of the top and bottom ‘content systems’ might affect legibility and comprehension. The contrast ratio between the deep red font and dark grey background make the words hard to see and focus on. The terminology used in the example on the top over complicates a relatively simple to understand value proposition.

The top part of the image has red comic text on a grey background that reads "We manufacture and distribute cushy footwear with a proprietary mixture of recycled yoga mats and tertiary packaging". The bottom part of the image has black sans serif font on a white background that reads "We make comfy shoes from recycled materials".
Two different content designs to advertise comfy recycled shoes on a website. One’s easier to read and understand than the other.

This might seem like an extreme example, but if you lived through the internet of the 90s, you’ll remember websites with comic fonts and crazy backgrounds… you’ll probably never forget. Good recommendations identify specific design characteristics along with concrete or tangible ways to improve them. In the example above, the Human Factors specialist would say that the top text needs to be re-designed so that the text and background have a contrast ratio of at least 4.5:1, whereas the bottom text already meets this design standard.

Identifying Human Characteristics to Accommodate

Any aspect of human psychology or physiology involved in the way people interact with your website (e.g., read the content) could be considered relevant. For the most part, the availability of existing design standards for web design preclude the need to get into the weeds documenting specific Human characteristics for a website evaluation project. But those standards would have their basis in a more detailed understanding of human limitations and capabilities. For example, knowing the limitations of the human visual system informs minimum contrast ratios. Knowing something about the education of your target audience (e.g., is the website for elementary students or graduate students) will inform the recommended reading level.

One important consideration regarding Human Characteristics is Accessibility, is the design of the website going to be accessible to all people who want to use it. The Web Content Accessibility Guidelines provide a series of recommendations to ensure people of all abilities have access to content on the web. This would include things like designing to support blind or partially-sighted persons who are using screen readers.

Wrapping it up

To summarize, Human Factors is all about designing better systems by applying knowledge about humans in the design process. While it sounds intuitive, there’s a large body of knowledge out there regarding both human characteristics and design best practices that Human Factors specialists have familiarized themselves with. The next time you’re wondering if Human Factors is relevant to a project you’re working on, ask yourself if you are designing something a human will use. If the answer is ‘yes’ then it’s worth your time to have a chat with your local Human Factors specialist.