5. Models

Question 1

What is Fitts’ Law?

Answer 1

A robust model of human psychomotor behavior
Predicts movement time for rapid aimed tasks (depending on distance, size of the object and the device)
Equation MT = a+b*log2(1+D/W)
Index of Difficulty ID = log2(1+D/W)
Throughput TP = ID/MT

Question 2

How can you calculate the constants for the device?

Answer 2

Linear Regression
Measure the MV with different distances and sizes
Fit a line through the measured points
a=interception b=slope

Question 3

What is Steerings Law?

Answer 3

Models the movement time for a pointer though a 2D tunnel
Equation MT = a+b*(1+D/W)
Index of Difficulty ID = (1+D/W)

Question 4

What is Hick’s Law?

Answer 4

Time needed to make a selection is proportional to the log number of alternatives
H = log2(1+n)

Question 5

What are descriptive Models?

Answer 5

Provide a basis for understanding, reflecting and reasoning about certain facts and interactions
Provide a conceptual framework that simplifies a potentially real system

Question 6

What is GOMS?

Answer 6

Goal, Operators, Methods, Selection rules

-Various variable parameters, difficult to target specific users, time consuming, …

Question 7

What is KLM?

Answer 7

Keystroke-Level Model
It can evaluate UI design, interaction methods and trade-off
Based on this shortcuts can be provided

Question 8

Name the KLM Operators.

Answer 8

K: Key press
B/BB: Mouse button press/click
P: Mause pointing
D: Mause drawing
H: Move hand between mouse and keyboard
M: Thinking
R: Response time from the system

Question 9

Describe Norman’s Action Cycle?

Answer 9

The world:
Evaluation: 
Perceiving the state of the world
Interpreting the perception
Evaluation of Interpretations
Goals:
Execution:
Intention to act
Sequence of actions
Execute the acton sequence