Human factors engineering (HFE) is a broad and multidisciplinary field that designs and evaluates the human interfaces of a system.
Don’t stop reading — that definition masks a lot of complexity. Let’s break it down:
INCOSE defines system as “an arrangement of parts or elements that together exhibit behaviour or meaning that the individual constituents do not. Systems can be either physical or conceptual, or a combination of both.”
Systems may include any combination of hardware, software, people, organizations, processes, information, facilities, services, tools, consumables, etc. A system can be as complex as the entire universe or as simple as two people interacting.
When people hear “human interface”, they usually think software or hardware interfaces. But, interfaces really encompass any human interfaces with any of the other system components as defined above.
A great example is Crew Resource Management, which is a system for pilot interpersonal communication and shared decision making. No other system components are involved, just the humans in the cockpit1.
Think of a trip to the grocery store. You propel the cart, observe price tags and product packaging, smell the prepared foods, hear the muzak, talk to the butcher, handle products, place items on the checkstand conveyor belt, talk with the cashier, use the card reader to pay, check the accuracy of the receipt, etc. All of these are interfaces with some level of design. There’s a whole field of study on grocery store psychology.
Design and evaluate
What does it mean to design and evaluate an interface?
Obviously, it’s highly dependent on the requirements and context of the system. This is where relevant human factors expertise is required to understand the aims of the system and the interfaces to be designed, decompose those into human factors objectives, and specify how success will be evaluated.
It’s best to specify the verification method before designing, to ensure that you’re clear on the goal you’re working towards. Common metrics include user satisfaction, accuracy and error rate, speed, situation awareness, workload, usability, and engagement.
Broad and multidisciplinary
HFE covers a range of fields that may include: human-computer interaction, anthropometry, physiology, psychology, macroergonomics and organizational psychology, cognitive science, industrial design, user experience, and more.
Because HFE is such a broad field, it may take a team of experts with different specialties to effectively address the range of considerations applicable to any given system.
You should now have a better understanding of the full scope of what it means that HFE designs and evaluates the human interfaces of a system.