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Year 2 > HCI > Flashcards

HCI Flashcards

1
Q

Fovea

A
  • Central area of retina packed with cones for sharp, high-detail colour vision
  • Covers only about 1 degree of visual angle
  • Less than 1% of the retina’s area but more than 50% of the visual cortex’s neurons
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2
Q

Periphery

A
  • For movements and greyscale contrasts
  • Contains mostly rods but has cones
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3
Q

Retina

A
  • Has 6 million cones for high-accuracy colour vision
  • Has a blind spot which the optic nerve passes through
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4
Q

Gestalt Principles

A

1) Simplicity
- Perceive stimuli in a way that is regular, symmetrical and simple
- Eliminate complexity and
unfamiliarity to create meaning

2) Proximity
- Nearby stimuli are grouped

3) Similarity
- Similar stimuli are grouped

4) Figure and ground
- Tend to see a figure on a ground
- Can be ambiguous

5) Focal point and salience
- Often achieved by dissimilarity
- Used as a means of guiding user

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5
Q

CIE Colour Space

A
  • Contains all visible colours
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6
Q

Additive color system

A

Colours are mixed by adding up primary colours (RGB)

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7
Q

Subtractive color systems

A

Colours are mixed by subtracting complements of primaries from white (CMYK)

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8
Q

Voluntary eye movements

A

Used to track objects

  • Fixation: holding gaze stationary (0.1 - 1s)
  • Saccade: jump to new gaze target (<0.1s)
  • Smooth pursuit
  • Vengence shift: looking at a point closer/further
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9
Q

Involuntary eye movements

A

Enhance vision and prevent eye fatigue during fixations

  • Microsaccade: small jump
  • Drift: slow, roaming movement
  • Tremor: fast, small oscillation (about 90 Hz)
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10
Q

Cognitive processing time

A

Between 70-300ms

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11
Q

Low Fidelity Prototype

A
  • Uses a medium unlike the final medium
  • Quick, cheap and easy to change
  • Examples: sketches of screens, task sequences, post-it notes, storyboards

Advantages:

  • Low development cost
  • Evaluates multiple design concepts
  • Useful communication device
  • Addresses screen layout issues
  • Useful for identifying market requirements
  • Proof of concept

Disadvantages:

  • Limited error checking
  • Poor detailed specification to code to
  • Facilitator driven
  • Limited utility after requirements established
  • Limited usefulness for usability tests
  • Navigational and flow limitations
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12
Q

High Fidelity Prototype

A
  • Looks like or more like the finished product
  • Provides demonstration of functionality
  • Example: dynamic wireframe

Advantages:

  • Complete functionality
  • Fully interactive
  • User driven
  • Clearly defines navigational scheme
  • Use for exploration and test

Disadvantages:

  • More resource intensive to develop
  • Time consuming to create
  • Inefficient for proof-of-concept designs
  • Not effective for requirements gathering
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13
Q

Users for designing a new interactive system

A
  • Those who interact directly with the product
  • Those who manage direct users
  • Those who receive output from the product
  • Those who make the purchasing decision
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14
Q

Direct manipulation examples

A
  • Using a mouse to move a file on a desktop
  • Using a gesture to open an app
  • Using digital blocks to compose music
  • Kicking your foot to open the boot of a car
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15
Q

Requirements

A
  • Requirements often need clarification, refinement, completion, re-scoping
  • They can change during the course of a project
  • There are functional and non-functional requirements, both of which are important for a system
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16
Q

Use cases

A

Provide a step-by-step breakdown of the interaction between a user and a system

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17
Q

Troxler’s Fading

A

The lilac discs tire out the red and blue cones, so green cones dominate when a disc is removed and a green afterimage appears. After a while the green afterimages cancel out the lilac disks

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18
Q

Student’s t-test

A
  • The two most frequently used types of t-test
  • Calculates the likelihood of a difference between two sample means given that they are from the same population
  • One-tailed test is used for a directed hypothesis
  • Two-tailed test is used for an undirected hypothesis
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19
Q

Motion parallax

A
  • Motion parallax, simulated using head tracking
  • Defocus blur, simulated using foveated rendering
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20
Q

Binocular depth cues

A
  • Stereopsis and convergence
  • These can be simulated using stereoscopy
  • Horizontal human FoV: 210°
  • Vertical and horizontal 3D FoVs: 150° and 120° respectively
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21
Q

Immersion

A

Replacing real-world sensations with virtual sensations

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22
Q

Presence

A

Sensation of being there, as a result of immersion

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23
Q

Contextual Inquiry

A
  • Interview while being observed
  • Users involved in contextual inquiry are observed and questioned while they work in their own environment
  • Four principles:
    1) Context
    2) Partnership
    3) Interpretation
    4) Focus
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24
Q

PCCR

A
  • Stands for Pupil Center Corneal Reflection
  • Often in combination with head and face tracking or other glints to determine eye distance from tracker
  • The accuracy is limited by fovea (about 0.5 degrees), eye movements (during fixtation), calibration and hardware limits
25
Q

Eye-gaze controlled UIs

A

Challenges faced:

1) Size of the fovea
2) Involuntary eye movements
3) Midas touch
4) Problem of how to click

26
Q

Cognitive processes

A
  • Attention
  • Memory and working memory
  • Reasoning
  • Knowledge
  • Comprehension and production of language
  • Judgement and evaluation
27
Q

Nielsen’s 10 Usability Principles

A
  • Visibility of system status
  • Match between system and the real world
  • User control and freedom
  • Consistency and standards
  • Error prevention
  • Recognition rather than recall
  • Flexibility and efficiency of use
  • Aesthetic and minimalist design
  • Help users recognize, diagnose, and recover from errors
  • Help and documentation
28
Q

Fitts Law

A
  • Predictive model of human movement
  • A function of the ratio between the distance to the target and the width of the target
  • Used to model the act of pointing
  • The original formula has been modified to take different input devices into account

ID = a + b.log₂(A/W + 1)

29
Q

Sharp, Rogers and Preece

A
  • Affordance
  • Constraints
  • Visibility
  • Feedback
  • Consistency
  • Mapping
30
Q

Color blindness

A
  • Red-green is the most common form
  • Mostly affects males
31
Q

Task analysis

A
  • Used to obtain descriptions of what people do
  • Links actions and objects to make up procedures
  • Criticised for being divorced from people’s situation of work
  • Allows for maximum positive transfer of users’ existing knowledge
32
Q

Null hypothesis

A

There is no difference or difference in another direction from what was expected

33
Q

Alternative hypothesis

A

There is a difference in a certain direction

34
Q

Testing hypotheses

A

p ≤ α:

  • Reject null, accept alternative
  • However could make a type I error (“false positive”)

p > α:

  • Accept null, reject alternative
  • However could make a type II error (“false negative”)
35
Q

Design patterns

A
  • Describes a solution to a problem in a certain context
  • Capture design experience, but that doesn’t necessarily mean good design
  • Web design patterns include pagination and lazy registration
  • There are design patterns for specific types of user interfaces, such as the web and mobile apps
36
Q

Main tasks for collaboration

A
  • Communication
  • Cooperation
  • Coordination
37
Q

Variables for classifying collaborative system

A
  • Time
  • Place
38
Q

Norman’s Theory of Action

A

Stages of Execution:

1) Establishing a goal
2) Forming an intention
3) Specifying an action sequence
4) Executing the action

Stages of Evaluation:

5) Perceiving system state
6) Interpreting system state
7) Evaluating system state wrt goals and intentions

39
Q

Common ground

A
  • Allows design teams to establish a set of commonly agreed terms
40
Q

Norman’s Conceptual Framework

A

Makes explicit the relationship between:

1) How a system should function
2) How it is presented to users
3) How it is understood by them

41
Q

Norman, Ortony and Revelle’s Model of Emotion

A
  • Visceral
  • Behavioural
  • Reflective
42
Q

Usability Testing

A
  • Often includes think-aloud protocol
43
Q

Quantitative methods

A
  • Usually produce data in the form of numbers
  • Can be combined with qualitative methods fairly easily
44
Q

Qualitative methods

A
  • Usually produce data in the form of text
  • Can consist of think-aloud protocols
45
Q

Independent variable

A
  • The variable of which we want to know the effect
  • Levels = the different values to try out and compare, which lead to conditions that need to be tested
46
Q

Dependent variable

A
  • Variable that describes the effect being investigated
  • Needs to be measurable as accurately as possible
47
Q

Anti-pattern

A

Illustrate solutions with bad usability that designers should avoid

48
Q

Anthropomorphism

A

The use of characters with human-like properties

49
Q

Threats to validity

A

1) Misunderstandings

2) Order bias
- Means that the order of tasks has an effect on measurements
- Counter-balance task order to distribute the bias

3) Training Effect
- Training phase before each type of tasks
- Counter-balance task order to distribute effect

4) Fatigue
- Participants get tired after hard tasks
- Schedule breaks after every n tasks
- Counter-balance task order to distribute effect

5) Social Desirability Bias
- Participants tend to do what is socially expected

6) (Self-)Selection Bias
7) Confounding Variable
- Variable that is not controlled, but has an effect

50
Q

Social Desirability Bias

A

Means participants tend to do what is socially expected

51
Q

Binaural hearing

A
  • Delays and attenuation give clues as to the sound position
  • Model does not account for symmetrical lateral positioning
52
Q

HRTF

A
  • Stands for head-related transfer function
  • The ratio of pressure at
    the ear to pressure at the
    centre of the head

For synthesising HRTF:
1) Capture head mesh using
laser scanner
2) Compute the waveform as it propagates, this avoids the need for the anechoic chamber

53
Q

Guiard’s Model of Bimanual Skill

A
  • Humans are not only two-handed, they use their hands differently
  • A non-preferred hand:
    1) Leads the preferred hand
    2) Sets the spatial frame of reference for the preferred hand
    3) Performs coarse movements
  • A preferred hand:
    1) Follows the non-preferred hand
    2) Works within established frame of reference set by the non-preferred hand
    3) Performs fine movements
54
Q

Defining Tasks

A

They must be:

1) Relevant
2) Well-defined
3) Realistic
4) Variations
5) Well-timed

55
Q

Remote eye gaze tracker

A
  • An infrared illuminator is used to create a reflection on the cornea
  • The vector between the pupil and that reflection gives an indication where the user is looking at
56
Q

Theory of Reasoned Action

A

1) Attitude (individual evaluation of a behaviour)
2) Subjective norm (how society or environment contributes to
behaviour)
3) Intention (indication of an individual’s readiness to perform a given behaviour)
4) Behaviour (observable response in a given situation with respect to a given target)

57
Q

Theory of Planned Behaviour

A
  • Perceived behavioural control (the extent to which the individual believes they can control behaviour)
  • Beliefs about whether factors that will affect the difficulty of the behaviour
  • Perceived power of these factors
  • Number of factors
58
Q

Microsoft Clippy

A
  • Had an intelligent user interface
  • Was disliked by many, regarded as annoying, distracting, patronising, intrusive

Year 2 (5 decks)

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