Factors Affecting the Choice of User Interface

We’ve seen that there are several types of user interfaces and we use them for different reasons and different devices. But how do we choose which user interface would be correct for a certain situation?

Imagine you were designing an affordable tablet aimed at very young children. What user interface would you use? How would you go about making that decision? Well, there are several factors that will affect your choice of user interface.

In this lesson, we’ll learn about the factors affecting the choice of user interface, including:

  1. Ease of use, user experience & accessibility
  2. Performance/response time, user requirements & storage space

1. Ease of Use, User Experience & Accessibility

One of the most important things to consider when choosing a user interface is about whether your users would be able to understand and make use of the interface. This is more than just if the interface is “easy to use”.

In this section, we’ll consider three factors. Ease of use, user experience and accessibility.

Ease of Use

This is about how simple and intuitive the user interface is to navigate and perform tasks on. It’s important to choose a user interface that is easy to use, as a difficult user interface will reduce productivity and increase training costs (as you’ll need to spend more time teaching employees to use the interface).

The ease of use of a user interface depends on the type of task being performed and what device is being used. For example, a graphical user interface would be easy to use on a desktop computer but would be very difficult to use on your washing machine.

User Experience

Ease of use can also be relative to the experience your users have. We’ve learnt previously that a technical IT user might find a text-based interface easy to use. However, most of us would find it very difficult because we have never used that type of interface before.

The user interface we have the most experience with using will be easier for us to use and we will be more productive on. This is true even within the same type of user interface. For example, Windows 10 and MAC OS both have a graphical user interface. However, if you’ve only used Windows 10, but then are given a MAC to use, you’d find the interface very difficult initially, as the two interfaces, while both being GUIs, are actually quite different.

Accessibility

Another factor that affects how easy to use a user interface is, is how well the interface is designed for people with individual needs. Not all user interfaces are equally easy to use for people with disabilities.

For example, a speech interface can have good accessibility for someone with a visual disability as it doesn’t rely on sight at all. However, graphical user interfaces can be poor for someone with a visual disability as it naturally relies on vision a lot.

Some graphical user interfaces provide built-in accessibility tools to mitigate this, such as a screen magnifier and text-to-speech software. They are also often highly adaptable, including high contrast colour schemes and being able to change the size of icons, menus & pointers. However, some GUIs are better at this than others.

Further Thought

Do you think that a text-based interface would be accessible to individuals with visual disabilities? What about those with other disabilities, such as limited mobility?

2. Performance, User Requirements & Storage Space

It’s important that a user interface can do what we need it to, when we need it to and using the available resources we have. Not all interfaces have the same capabilities, so we need to choose the right interface for the right task.

In this section, we’ll consider another three factors. Performance/response time, user requirements and storage space.

Performance/Response Time

This is about how quickly tasks can be completed by using the user interface as well as how quickly the interface responds to user input.

We’ve learnt already that a text-based interface can be very quick to perform tasks if you know the command words. This is because many actions can be performed in a single command that would take navigating through several windows in a GUI. In addition to this, as text-based interfaces take less processing power than a GUI, this frees up more processing power for performing tasks, which could give faster response times.

Some interfaces have particularly slow response times. An example is a speech interface. Interpreting human speech is processor intensive and takes a long time to interpret. In fact, many speech interfaces will record your voice, send it over the internet to powerful servers, process the voice to figure out the command, and then send the result. This leads to slow response times.

User Requirements

This is about whether the user interface has the required functionality for what you are going to be using it for. Does it have the features you require and can it be relied upon to perform the tasks you wish to complete?

If we’re developing a controlling device, such as a security light system, then we would need a sensor interface as this is the type of interface that will constantly monitor sensors and automatically perform actions in response. However, if we’re looking for a user interface to allow us to browse the internet, send emails & write reports on a desktop computer, only a graphical user interface would have the functionality available to allow us to do this.

Storage Space

Some user interfaces require more storage than others in order to run. Not all computing devices have a large amount of storage though. While most desktops, laptops, tablets & smartphones will have a significant amount of storage, embedded systems and domestic appliances probably will not.

We’ve learnt that graphical user interfaces use up a large amount of storage space to store all of the graphics it uses. This is fine for computers, most handheld devices and entertainment systems, as they all typically have a lot of storage. But it would be a problem for a dishwasher, central heating system and vending machine.

Another type of interface that might require a lot of storage is a speech interface as it will need to store a recording of your voice to process your commands and figure out what you’re saying. Voice recordings take up a lot of storage. However, as we’ve learnt earlier these are often transferred to remote servers for processing and so devices with speech interfaces don’t necessarily require a lot of storage.

Further Thought

Consider the scenario from the lesson intro. You’re designing an affordable tablet aimed at very young children. What user interface would you use for the device and why? Using what you’ve learnt in this lesson, decide what type of interface and justify your decision.

Lesson Summary

So to summarise what we’ve learnt in this lesson:

  • Ease of use is about how simple and intuitive the user interface is to navigate and perform tasks on.
  • User experience is about whether the users have previously used the interface, or similar interfaces.
  • Accessibility is about whether the interface supports users with individual needs.
  • Performance/response time is about the speed that the interface can complete a task by.
  • User requirements is about whether the user interface has the required functionality for what you are going to be using it for.
  • Storage space is about the available permanent storage that the user interface requires to run.
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