Video Synopsis
Source: UX Design Basics: Mental Models by Jamal Nichols
“If the way something works lines up with your expectations, you’ll understand how to use it. And if it doesn’t, you will struggle.”
Definitions
- Usability
- A quality attribute that assesses how easy user interfaces are to use. The word “usability” also refers to methods for improving ease-of-use during the design process.
- Mental Model
- A mental model is how you think something will work, based on your knowledge and experience.
- System Model
- How something works.
- Interaction Model
- How to use something.
Key Takeaways
If the mental model closely matches the actual behavior of the device or interface, then people can:
- make accurate predictions;
- make correct decisions;
- choose appropriate actions.
Case Study: The Rocket Switch Gearshift
Figure 1: The Rocket Switch Gearshift is an example of a good System Model but bad Interaction Model.
In early 2006. Fiat Chrysler Automobiles recalled over one million vehicles due to a new shifter design known as the “Rocket Switch Gearshift”.
It ratcheted through park, reverse, neutral and drive but it would return to the centre position (i.e. what most people would assume is park). Driver confusion led to 266 crashes and 68 injuries, including the death of actor Anton Yelchin.
It was a failure in interface design. But, how did this happen?
System Model vs interaction Model
Figure 2: The system model is how something works while the interaction model is how we use that something.
Engineers (the people who build products) usually have strong System Models but they often have weak Interaction Models.
An automotive engineer will know how a car’s engine and drive train work but they won’t necessarily understand how an average person drives their car.
Conversely, the average driver prefers to be comfortable over knowledgeable.
The Role of the designer
Designers fill the gap between the builders and the users. A great designer has strong system models and strong interaction models.
“It’s a good idea for designers to learn how to code… You should, at least, have coded one project from start to finish… After that, you’ll understand systems much better and it’ll make you a better designer.”
Key Principle: If you’re creating something unfamiliar, base it in the familiar
Examples
Figure 3: Apple Notes app interface mimics a physical note pad.
Figure 4: Apple Address Book app interface mimics a physical address book.
Figure 5: The original Mac Desktop mimics a physical office space.
Figure 6: The very first cars looked like horseless carriages.
Fact: Mental models can evolve over time
As a designer, you may get to a point where you can take full advantage of a digital interface. But, first users need to build up that knowledge.
Figure 7: Eventually Apple was able to adopt a flat interface for its Address Book and take full advantage of a smartphone’s capabilities.
Evolving the gear shifter
Figure 8: Car makers are now moving to a rotary dial to completely replace the gear shifter entirely. In its place: cup holders!
While this interface still has its problems, it has faired better than the Rocket Swift Gearshift.
Why is that?
Activities
In groups of 3 or 4:
1: Mental Model fishbowl
Explore the concept of mental models in product design.
- What is the problem that the Rocket Swift Gearshift was trying to solve?
- Why did it fail, while the rotary dial gear shifter failed less?
Nominate a member of your group to summarize your findings in the main room.
2: User Interface show-and-tell
You found an example of product design in your home, office, etc (you may also find examples online):
- What problem is the product trying to solve?
- Describe its System Model and compare it to its Interaction Model. Is it a simple or complex problem from an System Model perspective?
- Can you think of a product that has a good Interaction Model but bad System Model? Vice versa?
- If it’s bad, how would you fix it?
- If it’s good, how could it be better?
What was your favourite product design example? It be yours or one of your classmate’s examples.