Expert evaluations provide alternatives to user evaluations for assessing designs and usability. Cognitive walkthroughs involve experts thinking like users to evaluate tasks in a system. Heuristic evaluations assess how a design conforms to predefined usability guidelines. Common guidelines include Nielsen's 10 usability heuristics, Norman's 7 principles of design, and Schneiderman's 8 golden rules. Using multiple expert evaluators is recommended as different people often find different usability issues.

1. 2013
Game Design 2
Lecture 6: Expert Evaluation
http://gcugd2.com
david.farrell@gcu.ac.uk

2. Expert Evaluations &
Design / Usability Heuristics
Will look at:
• Need for alternatives to user evaluation
• Methods of evaluating without end users
(using expert evaluators)
• Some heuristics / guidelines offered by
experts

3. End User Evaluations
• End-user evaluations can be expensive
– The methods are very time consuming
– Users may not be willing
– To get truly ‘fresh’ eyes, so called “kleenex”
testing requires different players each time
• Concerns about leaks
– Few external play testers at early stages
– Friends & family play testers may be too kind

4. Expert Evaluations
• As an alternative to some user testing,
expert evaluators / testers can be used
• Falconer details 10 inspection methods,
we will look at two:
– Cognitive Walkthrough
– Heuristic Evaluation

5. Cognitive Walkthrough
• In this approach experts imitate users
– Relatively quick and cheap
– Expert needs to be skilled in the system or to
be familiar with the prototype / design.
• Two phase process
– gathering inputs
– doing the walkthrough

6. Cog Walk Phase 1
• Two phase process.
• Phase 1: Gathering Inputs
•
•
•
•
A description of users (e.g. level of experience)
A description of system (or an operational system)
A description of the task to be carried out
A list of the actions required to complete the task
– step by step!

7. Cog Walk: Phase 2
• Phase 2: Walkthrough
– take each of the actions in the list
– and ask the following questions:
• Is the goal clear at this stage?
• Is the appropriate action obvious?
• Is it clear that the appropriate action leads to the
goal?
• What problems (or potential problems) are there in
performing the action?
• Essential that the expert tries to think like
the end user and not like themselves.

8. Cognitive Walkthrough
• For each step of the process, you ask
those questions and you write a ‘success
story’ - is it likely that the user will
successfully achieve this step. If not, why
not?

9. Consider Dwarf Fortress
• A scenario:
– Task is to make beds for your dwarves
– what are the actions?
•
•
•
•
•
•
open designate menu,
choose ‘chop down trees’
select trees
construct carpenter’s workshop
open workshop menu, ‘add’ beds
look at dwarves - make sure there exists a dwarf with ‘wood
chopping’ and another with ‘carpentry’
• (even these actions are not low level enough - I’ve
abbreviated for ease of presentation)

10. Heuristic Evaluation
• Involves assessing how closely an
interface or system conforms to a
predefined set of guidelines or heuristics.
• Examples:
– Nielsen’s usability heuristics
– Schneiderman’s eight golden rules
– Norman’s seven principles

11. Nielsen’s Usability Heuristics
•
Give feedback
– keep users informed about what is happening
•
Speak the user’s language
– dialogs should be expressed clearly using terms
familiar to the user
•
User control and freedom
– clearly marked exits and undo/redo
•
•
Consistency and standards
Prevent errors
– even better than having good error messages

12. Nielsen’s Usability Heuristics
•
Minimise memory load
–
•
Shortcuts
–
•
don’t have irrelevant or rarely needed information
Good error messages
–
•
accelerators (unseen by novices) speed up
interactions for experts
Aesthetic and minimalist design
–
•
recognition rather than recall
should indicate the problem and explain how to
recover
Help and documentation
–
should be concise and easy to search

13. Norman’s 7 Principles
1: Use both knowledge in the world and
knowledge in the head.
2: Simplify the structure of tasks.
3: Make things visible.
4: Get the mappings right.
5: Exploit the power of constraints.
6: Design for error.
7: When all else fails, standardise.

14. Schneiderman’s heuristics
(8 Golden Rules)
1.
2.
3.
4.
5.
6.
7.
8.
Strive for consistency
Enable frequent users to use shortcuts
Offer informative feedback
Design dialogues to yield closure
Offer error prevention & simple error handling
Permit easy reversal of actions
Support internal locus of control
Reduce short-term memory load
(Faulkner Chapter 7)

15. How Many Evaluators?
Different people find different problems.
http://bit.ly/heuristichowto

16. How Many Evaluators?