Heuristics and Modelling

Question 1

What are Nielsen’s 10?

Answer 1

1. Visibility of system status
2. Match between system and the real world
3. User control and freedom
4. Consistency and standards
5. Error prevention
6. Recognition rather than recall
7. Flexibility and efficiency of
   use
8. Aesthetic and minimal design
9. Help recognise, diagnose and recover from errors
10. Help and documentation

Question 2

What are Shnedierman and Plaisant’s 8?

Answer 2

1. Consistency
2. Cater to universal usability
3. Informative feedback
4. Dialogues yield closure
5. Error prevention
6. Permit easy reversal of actions
7. Locus (internal) of control
8. Reduce short-term memory load

Question 3

What is a usability inspection?

Answer 3

Contrary to user study. Experts evaluate a system based on heuristics. This is a holistic evaluation (it doesn’t focus on specific tasks, rather the whole system)
Single experts rarely find all the issues, better to use many.

Question 4

What is a cognitive model?

Answer 4

A cognitive model aims to model how users will interact with an arbitrary user interface. They aim to specify the...
- mental representations
- operations
- problem solving strategies
...that occur when users perform tasks

Question 5

What are the two primary cognitive models?

Answer 5

Predictive

• aims to predict user performance
• models interaction as a series of steps with predicted times for each
• can be done without users, in theory

Simulation

• simulates actual human behaviour when interacting with a UI
• has inputs and outputs, can be based on real data from users ACT-R can be used to power a simulation

Question 6

What is a cognitive architecture?

Answer 6

It models all aspects of cognition. CogModels can be produced using them to generate a model of processes required to complete a task. The architecture restricts the models that can be built within it. Can generate artificial users that simulate actual users.

Question 7

what is GOMS?

Answer 7

GOMS is a predictive method that can be used to evaluate a UI before any users have actually used it
G: goals of the user
O: operators. actions that can be done in the interface like clicking and typing
M: methods. sequences of sub goals and operators that can be used to achieve a goal
S: selection rules. the rules by which a user chooses a particular method

GOMS breaks down tasks into a hierarchy of goals and sub-tasks using the 4 elements. there are often multiple ways of performing a tasks, methods will be preferred based on circumstance

Question 8

what is KLM-GOMS? what are its limitations?

Answer 8

• keystroke level model
• a subset of GOMS that only includes operators and methods
• predicts task completion times
• all operators has a specific execution time
• assumes expert, error-free behaviour
• ignores learning curve effects
• assumes we have a reliable fixed time estimate for every operator

Question 9

what is the checklist for KLM-GOMS?

Answer 9

1. define a high level activity (e.g. delete file) in a sequence of clearly defined tasks such as (select icon, drag to location)
2. create subroutines for repeated tasks
3. review analysis, are all low-level steps included?