Understanding HCI

Task Analysis

What is Task Analysis?

  1. Task Analysis is used to identify the sequence of tasks required to complete an activity.
  2. It involves breaking down tasks into discrete steps, and noting the order in which they occur.
  3. This is most useful when designing a new system as the computerised version should mimic the manual system in the type of and ordering of tasks as closely as possible, so that users can easily make the transition to the new computerised system.
  4. It should also expose areas of underproductivity which a computerised system could automate.

Any of the following methods can be used to collect information about a system:

Why Use it

The purpose of task analysis is to produce a clear understanding of what it is that the system must do. The next stage is to produce the interface. You’ll often notice that the second version of any software is always better and more suited to the user, than the first. This happens because ordinary users make remarks, suggestions, complaints and so on, that are taken on board by the design team.

Participants Needed

One expert is required to undertake the analysis.

Depending on the task being analysed, 1 or more users may be required to carry out the task.

Task List

For each major task carried out we need to ask and answer the following questions:

  • Identify the steps involved in the task
  • What information is used for each task?
  • What affects or causes error in task performance?
  • What are the good features of the system?
  • What are the bad features?
  • What skills are required for each task?
  • How are these skills acquired?
  • How are these skills maintained?
  • How do external factors (time constraints, environment) affect the task?
  • How could you 'improve' the experience of undertaking the task?

Conditions required

Normally the task is analysed under normal working conditions, similar to ethnography.

Limitations Of method

  1. As with ethnography, the user may behave differently if they are aware they are being watched.
  2. However, it is unethical to record somebody if they have not been told about it in advance


In small groups of two or three, consider the procedure of sending a message on a mobile phone.

  1. Answer question 1 above without looking at the phone. When you are happy that you have identified all the steps, write or draw the screens and compare the steps you have written to the actual steps involved.
    1. Are there any differences?
    2. What did you forget?
    3. Task analysis helps to miminise the likelihood of missing out steps.
  2. Now answer questions 2-12 above for the same task.
  3. Find someone with a different type of phone.
    1. Are the steps different?
    2. Which is better?
    3. Why?
    4. Can you suggest any other improvements?