Why Human Factors Isn’t Just Common Sense 

“It’s just common sense.” 

I’ve been told more than once that what I do for a living is ‘just common sense’. The implication being that I’m peddling snake oil to the engineering masses. The usual objection to Human Factors being done is that engineers and designers are intelligent people, and providing they think about what they’re designing, they’ll come up with something that suits the majority of people. 

How far do we have to look to find evidence that’s not the case? It's taken engineers 3 major iterations of the USB plug and socket to come up with one that doesn’t care about the orientation of how you insert it. (I have a working theory that all USB-A sockets are closed regardless of what orientation you try the first couple of times, and it’s only after you utter the magic incantation of “why won’t you go in whichever way I ****ing try” that it’ll accept the plug). 

Anyone who travels for work has probably had time to reflect on the baffling design choices that come about in hotels, like the rooms where every light has to be turned off individually, and usually with subtly different controls on each one. Sure, when I’m tired after flying across the Atlantic, what I really want is to turn the process of going to bed into a bizarre mix of hide and seek and a logic puzzle. 

Likewise, who decided hotel rooms all need a flashing red light on the fire alarm and to put it above the bed so it flashes at you all night as you try to sleep? Why do I need to know that it’s working okay, and why is a flashing red light the way they indicate it? (Plus, what am I supposed to do about it if it’s not working properly anyway?) 

I wonder if anyone who makes the decisions about hotel room designs ends up spending time in those rooms. Surely if they did, they’d come up with better solutions. Perhaps there’s no equivalent of a formative study in the interior design world? 

Fortunately, in the medical device world, using formative studies to test and influence device design is well established. All too often we see devices based on the principle of ‘if it works for me, it’ll work for them’. It usually only takes a few minutes with real end users to prove that isn’t the case. Likewise, all the untested assumptions that were built into the design often come crashing down as soon as the device is in a users' hands.  

When you investigate why, it’s usually because there was an expectation that every user would behave in the same predictable way. But people are a lot more variable than we like to think. As the old saying goes, ‘you’re unique, just like everyone else’. So, it shouldn’t come as a surprise that we can’t predict how everyone will behave. Ultimately, that’s where Human Factors is needed; you can only find out how users behave by testing a design with users.  

Medical devices need Human Factors. Surely that’s just common sense.