What does "Task" mean in this context?
The core of a usability test is the set of tasks that the test subject will be asked to complete during the test. These tasks should be based on operations that someone in the real world might want to use your software to accomplish. Each task should describe a single, concrete action, and should provide the test subject with all of the information she needs to complete it—for example, "Send an email to the email@example.com mailing list."
What makes a good task?
Good tasks are easy to understand, describe complete operations, and use language is which is familiar to your test subject. If you test subject has to struggle to understand what your task is asking, then it will be difficult for you to get valuable feedback from her. The interface that you are testing should be the only potentially confusing part of the test. Similarly, tasks should not be upsetting. As a general guideline, never ask a test subject to do something that you would feel uncomfortable doing.
When the interface that I am testing allows for it, and when I know my test subjects well enough to understand their interests, I am fond of giving my tasks a happy context, much like a role-playing game. For example, the first set of tasks below centers around an imaginary free trip to Australia that the test subject has won. I find that this approach helps to relax my test subjects, and increases their interest in the tasks, which in turn makes them more participatory in the test. If you don't know your test subjects well enough to know how they respond to such an imagined scenario, I would not recommend this approach. Further, you should avoid scenarios that complicate your tasks.
How many tasks do I need for a test?
A typical usability test should last between 15 and 30 minutes; both the experimenter and the test subject will be exhausted if the test lasts longer than half an hour. It is therefore important to tailor the number and difficulty of your tasks to the time which is available to you. Most tests I run at Novell have 3-5 tasks.
How should tasks be organized?
Finally, a word on organizing tasks: I tend to organize my tasks in order of those requiring the least familiarity with the interface to those which are dependent on understanding a bit about how the interface functions. In the event that a user cannot complete a task, you should be prepared to provide her with the necessary information to begin the next task. Two sample sets of tasks follow, which I used to test subsequent designs of the Evolution search bar.
Example 1. Tasks for Evolution's Search Bar:
Background: You recently won a 1-month trip to Sydney, Australia. Before you leave, you want to find the address and phone number of your friend, Laura, who lives in Australia, so that you can contact her when you get there. Unfortunately, you have about 5000 messages in your Inbox, and you are having trouble finding the emails that Laura sent you which contain her information.
- Laura's email address is firstname.lastname@example.org . Search through your inbox for all the emails from her.
- You realize that Laura has sent you about 200 emails, and you need to narrow your search further. Search through all the email from her for a message that contains her address information. The only part of her address that you remember is the name of her street -- Wallaby Dr.
- Now that you have found Laura's address, you don't want to lose it again. Find a way to save the results of your search so that you will always be able to find this email from now on.
- Roberto and Kimberley, two of the travel agents responsible for booking your trip have been emailing you every day for the past few weeks, sending you information about Australia. You remember that one of them sent you a list of restaurants in Sydney. Search through your inbox for mail from email@example.com or from firstname.lastname@example.org which contains the word "restaurants".
Note that these tasks progress from easiest to most complicated. Using the input from these tasks, I redesigned the search bar, and tested it again using the new set of tasks below.
Example 2. More Tasks for Evolution's Search Bar
Background: You are planning a surprise birthday party for your friend, Gina. You want to invite all of her close friends, but you don't know some of their email addresses. In the exercise, you will try to use Evolution's searching capabilities to find them.
- Gina's email address at work is email@example.com . Search through your Inbox for messages from her. Add the other recipients of these messages to your addressbook.
- Your search did not turn up as many results as you hoped. You wonder if Gina has been using a different email address. Search through your inbox for messages from firstname.lastname@example.org, or messages that include "Moretti" in their "From:" fields.
- Now, you are confident that you have found all of the mail that Gina has sent to you. Save your search (as "Mail from Gina") so that you can access it again in the future.
- You realize that you may have mail from Gina stored in different mail folders besides your Inbox. Re-run the "Mail from Gina" search in your "Friends" folder.