09 Motor Behaviour Models

Question 1

What is a predictive model? (AKA performance models)

Answer 1

Purpose: Predictive models are designed to make predictions or forecasts about future events or trends based on historical data and patterns.

Question 2

What are the characteristics of predictive model?

Answer 2

They use statistical algorithms, machine learning, or other computational methods to identify relationships and patterns in data.

Example: GOMS, Key-Stroke Model, Fitts’ Law

• Forecast what will happen without having to carry out research
• not delay the introduction of the interface ready for user testing
• a predictive model is an equation or calculation used to forecast an event:
  
  • time taken to move the mouse/press a button
  • reaction time of the interface
  • reaction time of the user

Question 3

What is a descriptive model?

Answer 3

Descriptive models aim to summarize and describe the main features of a dataset. They focus on providing insights into the data’s characteristics rather than making predictions.

Question 4

What are the characteristics of descriptive model?

Answer 4

They use statistical measures, data visualization, and other techniques to describe patterns, relationships, and trends within the data.

Example: Key-Action Model (KAM), Three-Stage Model

• describe a framework or context for thinking about a problem or situation
• used to inspect an idea or a system and make statements about their probable characteristics
• it provides a basis for understanding, reflecting, and reasoning about certain facts and interactions
• it helps to reveal flaws in the design and style of interaction

Question 5

What is the difference between a predictive and a descriptive model? What is the purpose and outcome?

Answer 5

1. PurposePredictive models aim to forecast future events or outcomes, while descriptive models focus on understanding and summarizing historical or current data.
2. OutcomePredictive models produce quantitative predictions or forecasts, typically in the form of numeric values or classifications, whereas descriptive models provide qualitative insights, visualizations, and summaries of existing data.Prof answer:Predictive models are mathematical and allow human performance to be analyzed analyticallyDescriptive models provide a framework or context for thinking about or describing a problem or situation. They generally do not yield an emprical or quantitative measure of user performance

Question 6

what is GOMS model?

Answer 6

The GOMS model, which stands for Goals, Operators, Methods, and Selection rules, is a predictive model used in human-computer interaction (HCI) to analyze and predict user performance in completing tasks.

• Goals, Operators, Methods, Selection rules
  Goals - the state the user wants to achieve e.g., find a website
  Operators - the cognitive processes & physical actions needed
  to attain the goals, e.g., decide which search engine to use
  Methods - the procedures for accomplishing the goals, e.g., drag
  mouse over field, type in keywords, press the go button
  Selection rules - decide which method to select when there is more than one

Question 7

use GOMS model to move the word HCI before INF2002 in a word document.

text: INF2002 HCI

Answer 7

Goal: Edit a document, i.e. move HCI before INF2002

Operators
* Move mouse
* Click mouse button
* Use keyboard shortcuts

Methods
* Delete the word and re-type: retype method
* Cut and paste using keyboard shortcuts: key-shortcut method

Selection Rules
* If remember shortcuts use key-shortcut method
* Else use retype method to attain the goal

Question 8

what is Key-Stroke level (KLM) Model

Answer 8

The model focuses on how long it takes users to actually use the HCI via hardware - i.e. perform a task using input device (interaction)

measurements of experts performing ‘low level’ actions or ‘operators’ are collected

the measurements are used to predict the time required to complete a task

Question 9

Explain the operators in KLM model

Answer 9

K - button press, keystroke (0.08s - 1.2s, mean 0.4s)

P - Pointing a target with the mouse (1.1s)

• this time differs depending on the distance to the target and the size of the target

H - Homing = Moving hand between mouse and keyboard (1s)

• movement between any two devices as well as the fine positioning of the hand

D - Drawing a straight line segments D(n, I) where n is the number of the line segments drawn and I is the total length of the line segments

M - Mental activity to prepare for next action, denotes the time a user needs for thinking of decision making( 1.35s)

R - Response time of the system, depends on the system, the command and the context of the command

Question 10

What is the benefit of using KLM model? What is the negative of using KLM model?

Answer 10

• Quick and easy way to design systems without the knowledge about memory cognition
• Task times can be predicted without having to build a prototype and recruit and test users, saves time and money
• Measures only one aspect of performance - task completion time
  
  • does not measure time to learn
• deeper representation of the user’s mental operations are not considered
• users differ regarding their knowledge and experience of different systems and tasks, motor skills and technical ability

Question 11

What is the difference between GOMS model and keystroke model in terms of scope?

Answer 11

GOMS comprehensively models a wide range of tasks, including cognitive processes, whereas KLM is specialized and primarily focuses on tasks involving keyboard and mouse input

Question 12

What is the difference between GOMS model and keystroke model in terms of components?

Answer 12

GOMS breaks down tasks into Goals, Operators, Methods, and Selection rules, encompassing cognitive processes and decision-making, while KLM simplifies tasks to basic actions like keystrokes and pointing

Question 13

What is the difference between GOM model and keystroke model in terms of application?

Answer 13

GOMS is versatile and applicable to various tasks and interactive systems for user behavior analysis and design, whereas KLM is specifically designed for predicting task times related to input efficiency and is commonly used in ergonomic and interface design.

Question 14

What is the difference between GOM model and keystroke model in terms of level of detail?

Answer 14

GOMS provides a high level of detail, covering cognitive processes and method selection, whereas KLM offers a simplified approach, focusing on predicting task times based on fundamental actions without delving into cognitive analysis.

Question 15

What is Fitt’s Law? What does it model?

Answer 15

• Fitts’ Law predicts the time to point at an object using a device as
  a function of the distance from the target object and the object’s
  width (size)
• Fitts’s Law describes the relationship between the size of a target, its distance, and the time it takes to reach it
• Fitts’ Law predicts human performance in pointing tasks
• Models the way users perform target acquisition actions

Question 16

What is the Fitt’s law formula?

Answer 16

MT = a+b log2 (D/W + 1)

Question 17

What is the Fitt’s law formula? Index of difficulty

Answer 17

ID = log2 (D/W + 1)

Index of Difficulty is a standard measure of task difficulty

Question 18

What is the Fitt’s law formula? Index of performance

Answer 18

IP = ID/MT

The Index of Performance (IP) is a measure of the time or effort required to complete a pointing task, and it is often used to compare different pointing tasks or input devices. The higher the IP, the easier the task is considered, as it indicates that the task can be completed more quickly or with less effort.

Question 19

How does Fitts’ Law help in designing interfaces?

Answer 19

1. Target Size: Fitts’ Law suggests that larger targets are easier to hit and require less time and effort to select. Designers can use this insight to make interactive elements, such as buttons, icons, and links, larger and more accessible, especially for touchscreens and input devices with imprecise control.
2. Placement /Distance:
   The distance to a target also affects movement time. Closer targets are quicker to acquire than those farther awayPlacing commonly used or critical actions in areas that are easier to reach can improve user efficiency.

Question 20

What is key-action model? And what does it show?

Answer 20

The key-action model will allow us to look at:

• how users will interact with keyboards
• what kind of shortcuts they will or can use to carry out tasks

This will show

• what the user is expecting the computer to do when they use certain shortcuts

Question 21

What is buxton’s three stage model?

Answer 21

Buxton’s Three-Stage Model is a descriptive model that explores the cognitive and perceptual aspects of interaction, offering insights into the broader user experience.

Buxton’s Three-Stage Model is a qualitative framework describing the cognitive processes involved in interaction.

Question 22

What is the difference between Fitt’s law and buxton’s three stage model?

Answer 22

Fitts’ Law is a predictive model that optimizes the physical aspects of user interaction, focusing on pointing and targeting tasks, whereas Buxton’s Three-Stage Model is a descriptive model that explores the cognitive and perceptual aspects of interaction, offering insights into the broader user experience.

Fitts’ Law provides a quantitative, mathematical model with a formula for predicting movement time, whereas Buxton’s Three-Stage Model is a qualitative framework describing the cognitive processes involved in interaction.