15. task models


This exercise is based on the mobile phone scenario on the web at: www.hcibook.com/e3/scenario/phone/

A user interface designer analyses Andy's behaviour with his original phone and realises that both scenarios A and B are part of a general pattern as shown in the Hierarchical Task Analysis (HTA) in Figure 15.8.

(i) Complete the HTA for phoning using the original phone taking into account scenarios A and B only and briefly describe your solution.
(ii) Do a complete HTA for phoning using the new phone based on scenario C only
(iii) You will find that scenario C (and hence your solution to part (ii)) does not quite fit into the general pattern in Figure 15.8.

Discuss whether the solutions to (i) and (ii) can be modified to emphasise their common features and whether this would clarify the overall task description.

Rough HTA
Figure 15.8. Rough HTA

answer available for tutors only

(i) This part is mainly a fleshing out of the 'find number' subtask. Students may choose to use the textual form of HTA and this is acceptable.

  • Simple answer for plan 1 would be one or other, but some students should think a bit more about what this is really like for users.


(ii) Main subgoals below

  • but students should either flesh out 2.1 and 2.2 or justify that this is unnecessary


(iii) Big difference is that the dialling of the number gets folded into finding it.

  • One solution is to transform the view of the original tasks (see below)
  • Alternatives may be to have a conditional sub taks 'dial number if necessary'
  • May also note here or earlier that waiting may be worth including as sub-task
  • But should be asking whether these are sensible tasks from a user perspective


Other exercises in this chapter

ex.15.1 (ans), ex.15.2 (ans), ex.15.3 (ans), ex.15.4 (ans), ex.15.5 (ans), ex.15.6 (tut), ex.15.7 (open), ex.15.8 (open), ex.15.9 (tut), ex.15.10 (tut), ex.15.11 (tut)

all exercises for this chapter