Input Models

Question 1

Models

Answer 1

• Models are representations of phenomena
  that help us understand how something
  works (or how it will work)
• As simple as possible
• As complex as necessary
• Models are never perfect
• Models are based on assumptions

Question 2

Goal-Crossing (differences)

Answer 2

Pointing
* Control and correction at end of
movement only
* Crossing object boundary and
stopping on object

Crossing
* Control and correct all the way
towards the goal
* Crossing through an object for
selection, no need to stop within
object boundary

Question 3

Fastest accessible points

Answer 3

Corners and Edges

Question 4

Keystroke-Level Model (KLM)

Answer 4

KLM defines a set of basic input operators with time estimates for their
execution

• Physical motor operators
• Pressing a key, Pointing with the mouse, Draw a line
• Move hand from one device to another
• Mental operator
• Mental preparation of a motor action
• System response
• Also to model time to make a decision, or to look for something
• Time the user must wait for a response

Question 5

Utility of KLM

Answer 5

Advantages
* Simplicity of the model: easy to apply
* Can be done from just sketches of an
interface
* Surprisingly accurate
* Appropriate for routine tasks
* Especially useful to compare alternatives

Limitations
* Assumes that the user is expert and the task
well-rehearsed
* Assumes error-free operation
* Not appropriate for tasks that involve
exploration or reasoning