Chapter 2: The Human Factor

Question 1

What is Newell’s Time Scale of Human Action?

Answer 1

It is a descriptive model that depicts the problem space by positioning different types of human actions in timeframes within which the action occur.

Question 2

What are the four bands that are part of the model? How are they structured?

Answer 2

• Biological band
• Cognitive band
• Rational band
• Social band

Each band is divided into three levels and has a label that suggests a worldview or theory of human action.

Time is ordered by seconds and appears on a logarithmic scale, with each level a factor of ten longer that the level below it. The units are microseconds at the bottom and months at the top.

Question 3

What is the most common dependent variable in experimental research in HCI?

Answer 3

Time - the time for a user to do a task

Question 4

Examples of tasks that are included within each band

Answer 4

Biological band: blinking, breathing

Cognitive band: menu design, text entry, gestural input

Rational band: web navigation, ubiquitous computing, social navigation

Social band: Workplace habits, user styles, online dating

Question 5

Human factors view of the human operator in a work environment

Answer 5

Monitors the state of the computer through sensors and displays and

Controls the state of the computer through responders and controls.

Question 6

What are the five classical human senses?

Answer 6

Vision, hearing, taste, smell and touch

Question 7

Four physical properties of a single sound

Answer 7

Intensity (loudness), frequency (pitch), timbre, envelope

Question 8

What is the somatosensory system?

Answer 8

The somatosensory systems inform us about objects in our external environment through touch (i.e., physical contact with skin) and about the position and movement of our body parts (proprioception) through the stimulation of muscle and joints.

Includes: touch, temperature, pain and body and limb position.

Question 9

What is tactile feedback?

Answer 9

In HCI tactile feedback refers to information provided through the somatosensory system from a body part.

All user interfaces that involved physical contact with the user’s hands (or other body parts) include tactile feedback.

Question 10

What are responders?

Answer 10

How humans interact (respond) with an HCI
- Usually done using upper body limbs
Hands are the main responder in HCI systems
- Example: finger to text, feet to walk, etc.

Question 11

Proprioception

Answer 11

Proprioception is the coordination of limb movement and position through the perception of stimuli within muscles and tendons - tightly coupled to the somatosensory system.

Question 12

What are the type types of voice responders?

Answer 12

• Speech to text: must be recognized by algorithms implemented in the software
• Non-verbal voice interaction (NVVI) : computer input using non-speed vocalized sounds such as pitch, volume, timbre, etc.

Question 13

What are the two types of eye responders?

Answer 13

• Through fixations and saccades (Text entry is one application of eye tracking for input control)
• Through eye movement and view direction (emulated computer mouse)

N.B the eye can act as both a sensor and responder

Question 14

What are the stages of brain processing?

Answer 14

1. Perception: occurs when sensory signals are received as input from the environment; association and meanings take shape
2. Cognition : process of conscious intellectual activity such as thinking, reasoning, etc.
3. Memory: stores perception and cognition via categorical sections

Question 15

What is psychophysics?

Answer 15

Psychophysics examines the relationship between human perception and physical phenomena.

In a psychophysics experiment, a human is presented with a physical stimuli and is then asked about the sensation that was felt or perceived.

Question 16

What is JND?

Answer 16

Just Noticeable Difference is a technique where a human is presented with a stimulus at variable intensities to discover what intensity is barley noticeable.

Its a common experiment goal to measure the JND in a stimulus.

Question 17

What is ambiguity and illusion?

Answer 17

Another property of perception - the human ability to develop multiple interpretations of sensory input.

Illusion is the deceptions of common sense. If illusions are possible in visual stimuli, it is reasonable to expect illusions in the other senses.

Question 18

How can we measure (in a rough sense) a cognitive operation?

Answer 18

As sensory stimuli and motor responses are observable and measurable. It can be divided into:
- Sensory reception (1 - 38 ms)
- Neural transmission to brain (2 - 100ms)
- Cognitive processing (70 - 300 ms)
- Neural transmission to muscle (10 - 20 ms)
- Muscle latency and activation (30 - 70 ms)

Total : 113 - 528 ms

Question 19

HCI and interest in language

Answer 19

In HCI, our interest in language is primarily in systems of writing and in the technology that enables communication in a written form.

Question 20

What is a corpus?

Answer 20

A large collection of text samples gathered from diverse and representative sources. Used to characterize and study a language in its written form.

Question 21

Word-frequency list

Answer 21

A corpus is sometimes reduced to a word-frequency list, which tabulated unique words and their frequencies in the corpus

Question 22

Shannon’s letter guessing experiment

Answer 22

Demonstration of language redundancy and entropy:
- Redundancy: what we know
- Entropy : what we do not know