Software Design

What is a systems approach in HCI

Analysing interaction in its wider socio-technical system rather than as an isolated interface

Why are design trade-offs central in HCI

Improving one property often worsens another such as speed versus accuracy

What is human-centredness

Designing around the people who use or are affected by the system

What is the egocentric fallacy

Assuming other users think and behave like the designer

What is interaction in HCI

The reciprocal influence between a person and an interactive system through the interface

Why is interaction emergent

It arises from user system activity and context together rather than from one alone

What is co-adaptation

Users and systems changing their behaviour over time in response to each other

What is a user interface

The part of the interactive system that the user encounters or that shapes perception of the system

What is the difference between design engineering and evaluation

Design creates what should be built engineering realises it reliably and evaluation assesses human-relevant qualities

What is verification

Checking that requirements are met

What is validation

Checking that the system is fit for purpose

What is testing in HCI

Evaluating behaviour by trying the system in realistic use conditions

What is direct manipulation

Acting on visible objects through incremental reversible actions with immediate feedback

Why does direct manipulation support exploration

Because users get instant feedback and can reverse actions

What is the main lesson from using models like Fitts law

Check that the model assumptions fit the task before applying it

Why is field research valuable in Lecture 1

It reveals real work hidden constraints and local workarounds that lab tasks may miss

What does it mean that perception is constructed

Perception is an active representation built from sensation attention and expectation

What is sensation

The physiological process that produces information about the environment

What is transduction

Converting physical energy such as light sound or touch into neural signals

What three things shape perception most directly

Sensory information attention and expectations

What is a key strength of vision in HCI

High bandwidth parallel processing

What are major limits of vision in HCI

Visible spectrum contrast field of view and foveated acuity

What is a key strength of hearing in HCI

Very fast processing and 360 degree coverage

What is a weakness of hearing in HCI

It is more serial and can be lost in auditory clutter

What is tactition in HCI

Touch based sensing and haptic perception local to body contact

What are the three main eye movement types

Fixations saccades and smooth pursuit

What is a fixation

A period of relatively stable gaze used to encode information

What is a saccade

A fast ballistic eye movement during which visual information is not effectively sampled

What is smooth pursuit

Continuous eye tracking of a moving target

What is perceptual organisation

How the visual field is divided into figure and ground and grouped into regions

What is figure ground perception

Seeing some elements as foreground objects and others as background

What is the Gestalt law of proximity

Elements close together are grouped together

What is the Gestalt law of common area

Elements inside the same bounded region are grouped together

What is the Gestalt law of similarity

Elements similar in colour size or form are grouped together

What is the Gestalt law of continuation

Elements following the same flow are grouped together

What is selective attention

Focusing attention on a desired object or location

What is vigilance

Sustaining attention over time

What is divided attention

Sharing attention across multiple objects locations or tasks

What is change blindness

Failing to notice a visible change due to disruption

What is inattentional blindness

Failing to notice a visible change because attention is elsewhere

What is visual saliency

The probability that visual features attract attention especially on first view

What is display clutter

Too many elements competing to be salient at once

What is motor control in HCI

The regulation of movement used for pointing grasping selecting and other actions

What is an end-effector

A body part used to act such as a finger hand or stylus tip

What does open-loop movement mean

Movement without ongoing feedback guidance

What does closed-loop movement mean

Movement guided by feedback during the action

What is an aimed movement

Trying to move to a specific target location

What is an interception task

A task with both spatial and temporal demands such as catching a moving target

What is the speed accuracy trade-off

Higher speed usually reduces accuracy and higher accuracy usually reduces speed

What does Fitts law model

Target acquisition time for pointing tasks

State Fitts law

MT = a + b log2 D divided by W + 1

What do D and W mean in Fitts law

D is target distance and W is target width

What is throughput in HCI motor tasks

A bits per second abstraction of input performance

State a common throughput formula

TP = average ID divided by average MT

What is an alternative throughput estimate

Approximately 1 divided by b from Fitts law

What is a crossing task

A target acquisition task that relaxes the stopping constraint of pointing

What is a steering task

Moving a cursor through a constrained tunnel

State the steering law

T = a + b integral of ds over W of s

What does the Hick Hyman law model

Choice reaction time in open-loop selection tasks

State Hick Hyman for equiprobable choices

T = a + b log2 n

Why is classifying the task important before using Fitts or Hick Hyman

Because the model only applies when the task structure matches its assumptions

What cognitive capabilities matter in HCI

Supervisory control memory attention reasoning and decision making

What does it mean that cognition is goal-directed

Goals shape what users notice remember and do

What is a key limit of working memory

Only a few active items can be maintained at once

What are the two components of mental effort

Task effort and state effort

What is self-determination theory

A motivation theory based on autonomy competence and relatedness

What is autonomy in SDT

Acting willingly and in alignment with oneself

What is competence in SDT

Feeling capable and effective in controlling outcomes

What is relatedness in SDT

Feeling socially connected and belonging with others

How can an interface support autonomy

By allowing meaningful choice and self-set goals

How can an interface support competence

By giving useful feedback progress and achievable challenge

How can an interface support relatedness

By enabling supportive social connection and sharing

What is the difference between collaboration and cooperation

Collaboration involves shared goals and joint responsibility while cooperation may only divide labour

What dimensions classify collaborative technology

Co-located versus distributed and synchronous versus asynchronous

What is coordination in collaborative work

Managing dependencies awareness articulation work and shared understanding

What are boundary objects

Shared reference artefacts that help different people coordinate

What is user research

Empirical work used to obtain and represent knowledge about users activities contexts and technologies

What is the aim of user research

Concrete design-relevant knowledge about real users and stakeholders

Why should user research be design-neutral

So it describes users before locking into a solution too early

Who matters in user research

Users non-user stakeholders and the target audience

What is the say do problem

The gap between what people say they do and what they actually do

Why does the say do problem happen

Tacit knowledge poor memory social desirability and difficulty imagining future behaviour

What is research strategy in user research

Choosing methods by balancing learning goals and resource constraints

What three trade-offs guide research strategy

Realism precision and generalisability

What is triangulation

Using multiple methods to study the same phenomenon

What is validity

Whether the conclusions drawn from research are warranted

What is internal validity

Whether the observed effect is really caused by the manipulated factor

What is construct validity

Whether a measure actually measures the intended concept

What is statistical conclusion validity

Whether the statistical inference from the data is reliable

What is external validity

Whether findings generalise to other people settings or tasks

What is reliability

Whether a method gives consistent results

Why does transparency matter in user research

So the design data analysis and conclusions can be inspected

Why does ethics matter in user research

Because data collection analysis and reporting affect participants and other stakeholders

What do interviews mainly study

Users subjective experiences views and interpretations

What is a structured interview

An interview with predetermined questions and often a fixed order

What is an unstructured interview

An interview with no fixed schedule or sequence

What is a semi-structured interview

An interview with guiding questions but flexible follow-up and order

What is an open-ended interview

A semi-structured interview that adapts to the participant responses

What is contextual inquiry

A semi-structured interview method carried out close to the real activity being studied

What are the four core principles of contextual inquiry

Context partnership interpretation and focus