Human-Computer Interaction

1. Human-Computer Interaction Task Analysis & Design Alexiei Dingli adingli@stmartins.edu

2. Task Analysis (1) • Analysis the process in which humans play a role • Study of systems in terms of human behaviour • How people use such systems? • What resources they use? • What they need to know to use such systems? • Involves • Observation • Recording • Usage of that knowledge to build systems which match user tasks & needs

3. Task Analysis (2) • Not only confined to the computer element • Tries to model all human activities involved • Used in the initial stages of system design • Clarification of required task • Requirements capture • Problems which we might encounter? • Which new features? • Which old features? • Innovation?

4. Task Analysis Techniques • Involve sub-dividing/decomposing tasks into • Meaningful • Manageable units • Such techniques include • Hierarchical Task Analysis (HTA) • Creates hierarchy & sequence of tasks, sub-tasks, etc. • Knowledge-based Task Analysis (KBTA) • Creates ordered lists of components / tasks • Systems analytic techniques • Decomposes tasks but the ordering is focused more on the system

5. Uses of Task Analysis • Analytical method to determine how people carry out work practices. It … • Analyses how existing computer systems support the tasks • Identify & group user tasks in a structured fashion • Design & implements prototypes • Assist in the redesign of existing interfaces • Help design support & training material • Help in requirement analysis

6. HTA (Annett & Duncan 1967) • Most commonly used form of Task Analysis • Graphical representation • Decomposition of high level task into constituent subtasks, operations, plans • Uses structure chart notation

7. HTA Notation

8. Starting the Analysis • Define the area of work • Break it down into main tasks • Break down main task into 4-8 subtasks; specify subtasks in terms of objectives • Draw subtasks as layered plans

9. Progressing the analysis (1) • Choose level of detail • Treat each branch consistently • Decide at which level to stop • “click mouse” v. “delete block of text” • Choose depth-first, breadth-first, or combo • Use hierarchical numbering convention • 1, 2, 3, then 1.1, 1.2, 1.3 and so on ...

10. Progressing the analysis (2) • Outline Plan for each task • Describe how tasks are carried out (at the next level) • Number steps in the sequence they should be followed. 

11. Progressing the analysis (3) • Types of plans include • Fixed Sequence • Optional tasks • Waiting for events • Cycles • Time sharing (simultaneously) • Discretionary (free will) • Mixtures 

12. Finalising the analysis • Check • Consistency • Accuracy • Completeness • Check numbering is consistent with decomposition • Check the accuracy of the notation

13. HTA Example 1 Hierarchy description ... How to clean the house? • 0. in order to clean the house • 1. get the vacuum cleaner out • 2. fix the appropriate attachment • 3. clean the rooms • 3.1. clean the hall • 3.2. clean the living rooms • 3.3. clean the bedrooms • 4. empty the dust bag • 5. put vacuum cleaner and attachments away

14. HTA Example 1 Plans • ... and plans • Plan 0: do 1 - 2 - 3 - 5 in that order. when the dust bag gets full do 4. • Plan 3: do any of 3.1, 3.2 or 3.3 in any order depending on which rooms need cleaning  

15. HTA Example 2 Diagram

16. HTA Example 2 Refinement

17. HTA Example 3 • How would you go about preparing a Microsoft word document?

18. HTA Example 3

19. HTA Example 3 Refined

20. HTA Outcome • Manuals • HTA provides structured information • Helps users transfer between one system & another • Requirements Capture • Provide information on • Existing operations, • objects & • ways of performing tasks • Interface design • Top level can be used as menus headers • Task sequence can be used for user-system dialogues

21. Exercise 1 • How would you go about sending an MMS complete with text and image?

22. Knowledge-Based Task Analysis • Creates taxonomies of a task • Similar to generic hierarchies • Aim is to classify • Knowledge needed to complete a task • Rather than • Classify the procedures • KBTA does not only show sequence but also • Links between elements • It provides a fuller model

23. KBTA Example 1 • Classifying motor vehicle controls objects • Motor vehicle controls • steering steering wheel, indicators • engine/speed • direct starter, accelerator, foot brake • gears clutch, gear lever • lights • external headlights, hazards • internal roof light • wash/wipe • wipers front, rear • washers front, rear

24. System Analysis Techniques (1) • Data Flow Diagram (DFD) • Describe flow of information between processes & stores • Adaptable to task analysis

25. System Analysis Techniques (2) • DFD Example – Book Ordering System

26. System Analysis Techniques (3) • Entity-Relational Models • Associated with DB design & OO analysis • Similar to KBTA since it describes objects & actions • But ERM explicitly defines relationships

27. System Analysis Techniques (4)

28. Requirements Gathering • From several sources • Existing documentation • +cheap, -does not offer direct information • Direct observation • Informally watching, observing, monitoring, using specialised recording equipment, walkthroughs • Interviewing • Elicit experts, to uncover task decomposition • Questionnaire • Answers to specific questions • Quantitative survey data • Qualitative survey data • Group discussions • Subjective data

29. Data Analysis – Card Sorting (1) • Technique for exploring how people group items, so that you can develop structures that maximize the probability of users being able to find items. • Is easy and cheap to conduct • Enables you to understand how 'real people' are likely to group items • Identifies items that are likely to be difficult to categorize and find • Identifies terminology that is likely to be misunderstood.

30. Data Analysis – Card Sorting (2) • Group the following elements together in 4 categories and give each group a title: • Films & Movies • Diving • Live Music • Hotel • Etiquette • Beaches • Architectural Sites • Night Clubs • Historical Monuments

31. Data Analysis – Kelly Grids (1) • Ways of getting at the conceptual structure of the problem space • Identifying some 'elements' in the application • These might be real things or concepts, but should be organized into coherent sets • For example, the set {Porsche, Jaguar, Rolls Royce, Mini, Driver} has an obvious odd man out: Driver • Elicitate new classes by • asking for the opposites of all elements and concepts • laddering to extract generalizations • elicitation by triads extract specializations • user is asked to take any three elements and specify a concept that applies to two of them but not to the third • For example, with {Porsche, Jaguar, Mini}, top speed might emerge as an important concept

32. Data Analysis – Kelly Grids (2)

33. Other Data Analysis Techniques • Noun-verb method • Noun tasks-associated object • Verb actions • Rating Scales • A scale based on descriptive words or phrases that indicate performance levels • Qualities of a performance are described (e.g., advanced, intermediate, novice) in order to designate a level of achievement Eats John Biscuit

34. Task Analysis + Interface Design • Detailed TA can be mapped onto functions of a system • Menus • Selections • Sequences • Etc. • Should be considered as an aid to design • It is an iterative process • User Oriented • It does not try to understand the user but • Observes behaviour + actions

35. Conclusion • TA is an Iterative process which • identifies new data • Confirms existing data • Rejects false data • Necessary to understand tasks which in turn is necessary for the design of the system • It highlights the importance of the user

36. Exercise 2 • Produce a high-level hierarchal task analysis showing how you would find information on a website. Assume the site has a search facility as well as normal links.

37. Exercise 3 • Consider the activity to make a telephone call. Record the actions in an HTA diagram. Start off simply assuming you know the number to dial.

38. Exercise 3 • Consider the activity to make a telephone call. Record the actions in an HTA diagram. Start off simply assuming you know the number to dial. • What if you had to find the number in an address book?

39. Exercise 3 • Consider the activity to make a telephone call. Record the actions in an HTA diagram. Start off simply assuming you know the number to dial. • What if you had to find the number in an address book? • What if the number was engaged?

40. Useful Links (1) • http://www.usabilitynet.org/tools/methods.htm

41. Useful Links (2) • http://www.enquirewithin.co.nz/BUS_APP/business.htm

42. Suggested readings for next week • Chapter 6 of Dix et al.