Assignment 2: Hierarchical task analysis

This week your assignment focuses on Hierarchical task analysis, which is a method that can help you understand and discover the structure of a task or a behaviour. Your assignment will contain three parts. First, you will conduct a hierarchical task analysis (HTA) on a user’s mental model of sharing photos via email using the phone. You will then create another HTA, this time on your own, for an alternative way of doing the same action. Lastly, you will compare the two models, and elaborate on the pros and cons of the two ways to approach the task. We covered HTAs in class, and at the end of the page you will also find additional readings and resources on HTAs.

Prepare for the tasks:

  1. Read some of the resources provided below on HTAs and revisit course slides so you are more familiar with its principles and structure.
  2. Familiarize yourself with how to share a photo via email on a mobile phone.

Task 1: Carry out an HTA based on a user’s mental model of sharing photos via email

Find a friend and ask them to show how to share photos from a phone via email. Let the user explain the steps they take. Make notes while you observe the user. Do not seek to correct the user if the sequence of actions has inefficiencies. If the user does not know how to perform this task, continue until you understand what the user is trying to do, and then show how the task can be performed.

Once you think you know what the user's task structure is like, thank the user and prepare an HTA diagram that describes how the user went about sharing photos on their phone using email.

Use the notation that Lane et al. (2006; find the paper in the end of this page) use in their paper's Appendix A. An example of such an HTA diagram is shown below. You can use it as the main reference when developing the HTA.


Note: It may be easier to first use a textual representation of the task (see lecture slides for "Non-graphical HTA") and then sketch the diagram with pen and paper before preparing the final diagram. These methods may make it easier for you to create the final diagram.

Task 2: Create an alternative HTA diagram for sharing photos via email using a phone

Your participant has probably demonstrated photo sharing in either of the following two general ways:

  1. Go to Photo Gallery, choose Share, select Email.
  2. Go to Email, choose Add attachment, choose the Photo...

In this Task 2, you have to create an alternative HTA diagram, depending on which of the two methods listed above was the one that your participant showed to you. Select the sharing method that your participant did not demonstrate, and perform a HTA for that sharing method on your own, and draw an HTA diagram.

(The participant may have of course demonstrated photo sharing using a third alternative method too. In that case you can choose either of the two methods listed above.)

Task 3: Comparison of the two HTA diagrams

Compare the two diagrams and identify the similarities and differences. Analyse the pros and cons of the two task structures by their execution speed, vulnerability to mistakes, and simplicity.

How to return this assignment

Your submission must be returned as a PDF, and it should include 1) HTA diagram from Task 1, and 2) HTA diagram from Task 2, and 3) a comparison of the two.

This assignment is carried out independently.

Return your assignment by 23:55 on Sunday 22 September 2019 as a PDF via this page.

Additional resources and readings on HTAs:

Benyon: Designing interactive systems, Chapter 11.

Ritter et al.: Foundations for Designing User-Centered Systems, Chapter 11. Link

Stanton: Hierarchical task analysis: Developments, applications, and extensions. Applied Ergonomics 37 (2006) 55–79. Link

Annett: Hierarchical task analysis. In E. Hollnagel (Ed.), Handbook of Cognitive Task Design. (pp. 17-35). Erlbaum. Link

Lane et al: Applying hierarchical task analysis to medication administration errors. Applied Ergonomics 37 (2006) 669–679. Link

Assignment 2 grading:

Full point answer: Student did all three tasks outlined in the exercise well. The two HTAs reveal the task structure to depths that are sufficient for understanding the structure of the task. The annotation follows the conventions set out in the example provided. The comparison of the two models is well articulated and elaborates on relevant features of the HTAs (i.e., vulnerability to mistakes, simplicity, speed). 

Marks will be deducted for missing tasks. Errors in the submitted tasks (i.e., insufficient level of hierarchy/wrong annotation/insufficient understanding of HTA fundamentals or incomplete comparison) will also result in point deductions.