When we’re talking about useability, there are five quality components at play learnability, efficiency, memorability, errors and satisfaction. In this lesson, I want to focus on two of them. Learnability and efficiency, learnability and efficiency are frequently confused or used interchangeably, and though they’re related, they’re different. Learnability considers how easy it is for users to accomplish a task the first time they encounter the interface and how many repetitions it takes for them to become efficient at that task. Efficiency is about how quickly users can perform a task once they’ve learned it. And the relative importance of learnability versus efficiency depends on the experience users have with the system. For example, new users want to be able to learn the system quickly and get to a point of optimal performance as soon as possible. But expert users want their time on task to be as short as possible. With that being said, I want to point out that a learnable system is not always efficient. For example, let’s imagine an expense reporting app with a step by step Wizzard workflow and a lot of instructions and explanation on how to expense receipt.
This system might be highly learnable and that users could successfully complete the task as fast as possible, even as they do it for the first time. But if we were to produce a learning curve by plotting a user’s time on task over a set number of trials, we would likely find the line to be pretty flat. Think about it. The user would need to go through the same screens and answer the same questions every time so they wouldn’t be able to complete the task much faster even as they become well versed in the interface. This type of design can feel like handholding to expert users and is inefficient for repeated use. Learnable but not efficient. If you’re in the situation, consider implementing accelerators or process shortcuts, which will help advanced users without leaving new users in the dark.
Designers must carefully balance learnability and efficiency in order to design for novice users, expert users and everyone in between.