User Interface Design for Games - II
In my last blog "User Interface Design for Games - I", I described the method for user interface design for games which was focussed on the "Goals" .
Now, let's talk about another important part of usability - "Procedures"
Procedure Basics
Goals is what you want to accomplish
Procedure is how you accomplish that task
There are many models which relate procedure to usability.
GOMS Model
There are two approaches for evaluating the procedural quality of an interface.
- The Keystroke-Level Model Method
- Operators and times for the keystroke model
GOMS procedure method model example
VCR Processor
Methods for recording a program is performance based.
People miss out "procedure" part of interface
When we generally talk of user interface, we believe that user interface consists of the input devices and what appears on the screen.
However, a better view is to consider the "procedures".
So, Interface also include the procedures used to accomplish a task.
Research Results
For an interface to be easy, simple and fast to use it should have easy and simple procedures.
GOMS Model
Goal
What is the goal the user want to accomplish with the system?
Operators
What basic actions the user can perform?
Methods
What procedure the user should focus to accomplish the task?
Selection rules
Which of the several methods should be applied to accomplish the goals?
Two well eastablished GOMS methodology
- Keystroke level method
- GOMS procedure model
The Keystroke-Level Model Method
Analysis:
1. Start with specified interface design
2. Choose one or more representative task scenarios
3. List the keystroke level events required in the scenarios
4. Insert mental operations for when the user has to stop and think.
5. Look up the standard execution time of each operator
6. Add up execution times for operations
7. The total is the estimate time to complete the task
Choose design for fastest predictions
Especially useful for :
Getting a quick, easily explained
Frequently repeated activities
Operators as times for Keystroke level method model:
K- Keystroke
Pressing a key or a button on a keyboard
Different experience level has different times
P - Point with mouse to a target on display
Follows Fitt's law
(Read my other blog baout Fitt's law)
B - Press mouse button
Highly practiced, simple reaction
H - Home hards to keyboard or mouse
W - Wait for system reboot
User is idle and cannot continue
M -Mental act of thinking
Routine, brief pause in stream of activity
"NOT" a deep thought
GOMS Procedure Model Method
Analysis:
1. Select a set of top-level user goals
2. Choose the specified interface design
3. Write out general procedures that user will have to learn to execute and accomplish a task
4. Assess learning and execution implementation of procedure
Informal : unneeded
Formal : Calculate prediction learning or execution time
Choose the design with best combination of learning and execution tasks
Especially useful for:
Assessing consistency and ease of learning
Predicting execution times for variety of situations
Cognitive walkthough is an important technique used in design evaluation.
"The cognitive walkthrough method is a usability inspection method used to identify usability issues in a piece of software or web site, focusing on how easy it is for new users to accomplish tasks with the system" - Wikipedia
The cognitive walkthrough method is based on the notion that:
Users learn better by doing and performing tasks on an interface than studying a manual
1) A cognitive walkthrough starts with a task analysis that specifies the sequence of steps or actions required by a user to accomplish a task, and the system responses to those actions.
2) The designers and developers of the software then walkthrough the steps as a group, asking themselves a set of questions at each step.
3) Data is gathered during the walkthrough, and afterwards a report of potential issues is compiled.
4) Finally the software is redesigned to address the issues identified.
The above are the broad steps for cognitive walkthrough.
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