Previously I have written about how usability is defined. Now I am going to discuss how a method known as cognitive walkthrough can be used to evaluate the usability of an application without hiring test users. 😲😊 The cognitive walkthrough is useful in capturing learnability issues.
Preparation for a cognitive walkthrough
First you have to define a task that is to be completed with the user interface in question. For example a task could be booking plane tickets from your city to Kuala Lumpur for the next Thursday. Once you have a task defined, try completing it with the user interface and take screenshots from every step and mark the correct interaction in them.
Performing a cognitive walkthrough
For each screenshot you have, you have to answer to the following questions:
- Will the user try to achieve the effect that the subtask has?
- Is it obvious to the user he needs to perform the required interaction to proceed in the task? For example, if the user has to go to the settings in order to turn the computer off, this step is not obvious.
- Will the user notice that the correct action is available?
- This is as simple as whether or not the correct action is visible on the screen. For example, is the button hidden somewhere and you have to scroll to see it?
- Will the user understand that the wanted subtask can be achieved by the action?
- Is the text of the button descriptive and are there competing alternatives? For example a search engine interface having two buttons: search and find would be confusing especially if the buttons perform different actions.
- Does the user get appropriate feedback?
- Does the user know that his action had a desired effect or failed? Even in the case of a failure, the system should provide a meaningful error message that helps the user recover from the error.
The cognitive walkthrough is a great tool in evaluating the learnability of a user interface. It doesn't reveal all UI problems, but it certainly helps you move to the correct direction. 😊