Usability Heuristics on Critical Systems — #1 Visibility of Status

Maria Meireles
UxD Critical Software
6 min readMar 1, 2021

One of the biggest names on the UX world, Jakob Nielsen, focused a large part of his career on usability and came up with several usability methods — including probably his most famous, the heuristic evaluation.

The heuristic evaluation allows us to identify usability issues in software by looking at 10 major points, the usability heuristics. These are 10 rules of thumb dictating the quality of interactions and usability.

As these 10 heuristics are not specific usability guidelines, they can be applied to different contexts to improve the user experience of any product— like critical systems. In my work, I use these heuristics quite often to guide me and help me explain some design decisions.

Based on the Nielsen Norman Group article Usability Heuristics, I decided to set up this series of 10 articles discussing each heuristic and how they can be applied to critical systems.

#1 Visibility of system status

As the name says, a design should always inform users about what is happening — users should know the current system status through the system giving them appropriate feedback within a reasonable amount of time.

So that users can find out the outcome of prior interactions and determine what to do next. Predicting interactions creates trust in the product — it makes the user feel like they’re in control.

1. Communicate the current system’s state; all user’s actions should have informed consequences.
2. Give quick feedback to actions.
3.Be transparent and keep the communication open.

Everyday life examples
An excellent example of good visibility of system status in real life is a lift. If you click the button to go to floor 3, you can usually see the destination, the current floor you’re on, and in some cases, the system will inform you if the lift is going up or down.

A classic: not only informs about the current floor but also about direction. Waldemar Brandt/Unsplash

The more information is missing, the harder it is to make a decision on how to react to certain situations. Imagine that you have two lifts in front of you; you are on floor 2 and want to go up to floor 5 quickly. One lift is currently on floor 5 and going down, the other is on floor 1 but going up. Which one should you call?

The second lift. How come? It’s all about information. The lifts gave you the right information so you could make a better and more efficient decision. If that information were not available, you would probably call both of them and have hope that at least one would not take long to arrive.

Another good example is online shopping. It’s a personal pet peeve if a product page doesn’t include any information about its availability. Imagine you search for a blue shirt, see one on the list, click on the product, view the product page, click ‘Add to Cart’, proceed to checkout, and right before paying… the product isn’t available! You would probably lose some degree of trust in the shop and probably wouldn’t return to the site in a hurry…

Pertinent information at the proper time empowers users to decide what to do next.

Visibility of system status for critical systems

Like in the examples given above, visibility of system status can be seen in different critical situations. Let’s take a look at the monostable shifter from the Fiat Chrysler Jeep (2014–2015 models).

The monostable shifter has almost no user feedback: instead of shifting a lever into different gears, the lever can move backwards and forwards while changing gears, but always returning to the centre. The way to know what gear the vehicle is in is to look at the indicator lights.

Fiat Chrysler Jeep’s monostable shifter
Gear indicator’s lights on the car’s dashboard.
How does the monostable shifter works?

The problem?

  • It is hard to determine which gear the vehicle is currently in and which it is changing to: the driver needs to look for the indicator lights and does not have tactile feedback.The task and feedback are completely different from other vehicles; users need to learn the new task and unlearn the previous way of doing it.
  • The task and feedback are completely different to those found in other vehicles; users need to learn this new task and unlearn the previous way of doing it.
  • The gear order is also different from the standard PRNDL, making it even harder to read the indicator lights’ visual feedback (notice the images above).
  • No warning feedback when a dangerous action is performed. When not in park, if the driver opens the doors and the brake pedals aren’t pressed, there is no feedback to let the driver know the car isn’t parked correctly.

What happened?

Drivers would have problems or misread the feedback, increasing the frequency of unintended gear selection — drivers couldn’t tell if the car was in park or not. More than 306 incidents, 117 crashes, 28 injures, and 1 death resulted from this design decision. The death was well-publicised: the actor Anton Yelchin was crushed against a mailbox pillar by his car. By the time of his death, this issue had been identified and was known for almost a year — yet nothing had been done to fix the problem.

Investigations were made on these models. I want to point out a particular investigation conducted by the National Highway Traffic Safety Administration (NHTSA), where a simple conclusion was reached. These cars ‘appear to violate several basic design guidelines for vehicle controls’.

Since 2016, and after a lot of public pressure, the Fiat Chrysler Jeep changed from a monostable to a polystable design.

Visibility of system status is essential to critical systems. If drivers had the correct information available, they could have taken more informed decisions, which would have prevented hundreds of unnecessary crashes, dozens of injuries and — potentially — the death of Anton Yelchin.

Final thoughts

The example of the Fiat Chrysler Jeep is just one of many.

But as a final thought, take a moment to put yourself in the Chrysler drivers’ shoes: how would you react in a situation where you had to complete a common daily task in a completely different way than what you were used to? Chances are, if this was your new car, you’d be fairly confused — which is not an ideal position to be in when driving.

This kind of empathic effort should have happened early on in the design phase of the car: test, test and test with real-life drivers… Is this task vital to a safe driving experience? How do drivers usually perform this task? What’s the impact of tactical feedback on this task? Is visual feedback enough? Should we need a video to explain how to perform the task of changing gears when driving this specific model?

This is the type of exercise we usually do to design. Still, it’s even more crucial in the critical systems where safety, mission, and business-critical systems are at stake.

What can we learn from the first heuristic?

To give appropriate feedback within a reasonable amount of time in a critical system, it’s not just about saving 3 minutes while waiting for an elevator. It’s about being able to act on time and with precision when lives are at stake.

Get in touch

Maria Meireles, UX Designer at Critical Software
Designing for critical systems