7. design rules

EXERCISE 7.12 [extra - not in book]

What are the three main categories of usability principle? Choose one of them, and define three principles that are included within it.

answer available for tutors only

Learnability includes

  • predictability: support for the user to determine the effect of future action based on past interaction history.
  • synthesizability: support for the user to assess the effect of past operations on the current state.
  • familiarity: the extent to which a user's knowledge and experience in other real-world or computer-based domains can be applied when interacting with a new system.
  • generalizability: support for the user to extend knowledge of specific interaction within and across applications to other similar situations.
  • consistency: likeness in input-output behaviour arising from similar situations or similar task objectives

Flexibility includes

  • dialog initiative: allowing the user freedom from artificial constraints on the input dialog imposed by the system.
  • multi-threading: ability of the system to support user interaction pertaining to more than one task at a time.
  • task migratability: the ability to pass control for the execution of a given task so that it becomes either internalized by user or system or shared between them.
  • substitutivity: allowing equivalent values of input and output to be arbitrarily substituted for each other.
  • customizability: modifiability of the user interface by the user or the system.

Robustness includes

  • observability: ability of the user to evaluate the internal state of the system from its perceivable representation.
  • recoverability: ability of the user to take corrective action once an error has been recognized.
  • responsiveness: how the user perceives the rate of communication with the system.
  • task conformance: the degree to which the system services support all of the tasks the user wishes to perform and in the way that the user understands them.

Other exercises in this chapter

ex.7.1 (ans), ex.7.2 (ans), ex.7.3 (open), ex.7.4 (ans), ex.7.5 (ans), ex.7.6 (ans), ex.7.7 (tut), ex.7.8 (tut), ex.7.9 (open), ex.7.10 (tut), ex.7.11 (tut), ex.7.12 (tut), ex.7.13 (tut)

all exercises for this chapter