This document provides an introduction to the HCI module. It discusses three aspects of HCI - software interfaces, ergonomics, and societal interaction. It outlines the module team and assessment details. It also summarizes several arguments for the importance of HCI, such as its increasing role in our lives and jobs. HCI involves understanding users and ensuring systems are designed according to human cognitive and physical abilities.

1. Introduction to
the HCI Module

2. Welcome to the HCI Module!
 Module Team:
– Meg Soosay (Module Leader)
– Sean Wilcock (Module Tutor)
– Professor Hissam Tawfik (Module Tutor)
 Contact Details in the Module Guide

3. HCI: An Introduction
Three broad aspects of HCI
• Software interface
• Often called ‘user interface design’
• Ergonomics
• Hardware interaction
• Societal interaction
The HCI module will look primarily at the first of these

4. Why is HCI Important? Some arguments…
 Increasing importance and pervasiveness of computers
– our lives are affected in some way by computing
 Users must understand the interactions
 Diversity of population/users
 So:
– system will not work unless users understand it
– users will not understand it unless the interface is
well designed
– therefore HCI is crucial!

5. 2nd Argument
Despite its contemporary nature, HCI’s origins are
humble
 Productivity-based applications bound to the
desktop
 Personal computing made everyone a computer
user
 User interface became a selling feature
 This highlighted deficiencies; hence the term
‘usability’
 The opportune emergence of cognitive science
 cognitive psychology, artificial intelligence,
linguistics, cognitive anthropology, and the
philosophy of mind

6. 3rd Argument
 Macaulay (1995) – much of the code of most systems is
written to deal with the user interface
 Usability engineering is now central to what many
computer scientists and IT professionals do - Leventhal
and Barnes
 Well designed usable systems ensure that staff are not
frustrated during their work and as a result are more
content and productive.

7. 4th Argument
Life critical systems
• Failure results in loss of life, injury or damage to the
environment
• chemical plant protection system
• railway signalling system
Mission critical systems
• Failure results in some failure in goal-directed activity
• spacecraft navigation system
• electronic stock exchange system

8. Two Final Arguments
6th Argument:
• Legislation - health & safety
7th Argument:
• Altruism/professionalism

9. Three Counter Arguments
 HCI is only part of the story
 It may be an ephemeral problem
 The argument for HCI applies only to interactive
systems

10. HCI – What does it involve?
 Psychology
 Physiology
 Sociology
 Computer science
 Software engineering
 Graphic design/typography

11. Summary
 Ultimately, if a system is well designed with HCI
techniques, interaction becomes natural.
 Much interest from many quarters:
• Producers
• consultancy firms (“interaction design is now
big business” (Preece et al 2011)
• Consumers
 There is an increasing job market for usability
specialists
 Important for your future careers “if students do not
know about user interfaces, they will not serve
industry needs” (Leventhal and Barnes 2008)
 HCI will almost certainly be crucial for your level 6
project!

12. HCI Assessment
The Usability Evaluation portfolio
– deadline 22/11/15 (worth 60%).
Exam to be held during week 13
– w/c 11/01/16 (worth 40%).

13. The H in HCI
Human Information Processing

14. Introduction
 Designing a user interface involves users.
 Must therefore take cognisance of human constraints and
differences
• and possibilities
 At least 3 realms to consider:
• physiology
• physical abilities and constraints
• cognitive psychology
• “mental” abilities and constraints
• social dimension
• eg cultural issues
 First 2 today, third one later in the module

15. Introduction
 Essential lesson:
• “As humans … we have certain limitations, both
cognitive and physical. Products designed to support
humans should take these limitations into account”
(Preece et al 2011).
• “Users share common capabilities but are individuals
with differences, which should not be ignored” (Dix et al
2004 p 11)

16. Physiology: inputs and outputs
 Humans have a number of inputs, eyes, ears, smell, taste,
touch, electrical
• can we use these for HCI?
 Humans also have a number of output capabilities:
• movement - arms/hands/fingers, feet, head, eyes
• design input devices, eg keyboard, mouse, with user
population in mind
 be aware of Accessibility and Health and Safety regulations

17. Physiology: vision
 Need to do 3 things in vision:
• receive the external stimulus
• process the image
• interpret the image
 Each has HCI implications

18. Receive the external stimulus
 We have better acuity in mid-range of the spectrum
(yellow tones)
• yellow therefore useful for warnings
 Red and blue harder to see
• avoid red for details on the screen
 8-10 colours maximum to use if using colour coding
 9% of males colour blind
 Few people have perfect vision
Courtesy of
http://www.allaboutvision.com/conditions/colordeficiency.htm

19. Process the image
 We can see a wide area (60 either side of our nose), but
detail only in a small area
 HCI lessons:
• people won’t be able to deal with detail in 2 windows at
once
• not more than one image in digital media
• movement is good for alerting peripheral vision and
getting attention
• have clear boundaries in icon design

20. Interpret the image
 Brain interprets nerve impulses from the eye
 Brings memory into play to do this
 May cause illusion or hallucination

21. An Example – The Stroop Effect
RED
GREEN
BLUE
RED
GREEN
RED
RED
GREEN
BLUE
RED
GREEN
RED
Name the colour the text is written in – a conflict of
processes

22. How many colours do you see?

23. Interpret the image
 brain interprets nerve impulses from the eye
 brings memory into play to do this
 may cause illusion or hallucination
 avoid this or use it when designing interactive systems

24. Cognitive Psychology
 General aim, arguably:
– make sure interface design “accords with universal
psychological facts” (Raskin 2000, p4).
– “if you want to develop effective, interactive systems,
then you need a fundamental understanding of your
users’ psychology” (Smith-Atakan, 2006, p 106).
 Two main topics:
– Memory
– Problem-solving

25. Memory
Memory is a critical limiting factor of human information
processing in the context of HCI
 Sensory store -
• optical/audio rates of input
• Is transient
• Decays rapidly
• Modalities – Iconic, Haptic and Echoic
 Automatic response -
• Part of perception rather than cognition
• We do not consciously choose what information is stored in the sensory
store, or how long it will be stored for
 may move into -

26.  Short-term memory -
– limited to 7±2 items
– chunking
– decay: few seconds
– may move into:
 Long-term memory -
– limitless?
– basic organisation is semantic
– access decay
Memory

27.  HCI implications of the model (cf. Smith-Atakan 2006):
 Sensory store
– if images on screen too fleeting, user will extract little
information
– analogous lesson for sound output
 Short-term memory
– be aware of limits to short-term memory
– consider quantity and time span of info
– minimise distraction during tasks and memorisation
– chunk info where possible (Benyon 2010)
– images help but should be accompanied by text
Memory

28. Memory – Long term memory
 Try to aid movement into and retrieval from LTM in HCI by:
– structuring information
– providing memory cues
– being consistent
 using meaningful command names
– eg Unix - CAT, GREP, LINT
– probably poor names, in retrospect
 using meaningful icons
 favouring GUIs where possible
– recognition rather than recall

29. Thinking and problem-solving
 Cognitive processing (thinking) is thought to involve mental
models (Preece et al 2011)
 Two types:
– physical
• describe relationships of objects in the world
– conceptual
• linguistically based
 Mental models are important in HCI - eg a graphical
metaphor should help user get correct mental model of the
system

30. Paying attention
 Paying attention” is an important part of cognitive
processing (Benyon 2010)
 We are good at selective attention paying and filtering
– We can attend to something without being aware of it
 Use this ability in the user interface:
– not too many competing demands
– avoid too many strong stimuli, eg bright colours
– attention tends to focus on change - hence in digital media
– animation and sound will “win” over text
– too much information  “cognitive overload” (“information
overload”)  stress and fatigue
– continuous repetitive tasks also  stress and fatigue
• design “closure events” into the interface

31. Norman’s seven stage model
 There are, then, many lessons from HIP to apply to HCI
 Norman (2004, cf. Benyon 2010) suggests a model of
interaction within which to apply these:

32. Norman’s seven stage model
 forming the goal
 forming the intention
 specifying the action
 executing the action
 perceiving the system state
 interpreting the system state
 evaluating the outcome

33. Norman identifies two “gulfs”
 gulf of execution
• between my intentions and what the system allows
• hence – prompts
• “affordances”
 gulf of evaluation
– user doesn’t understand what has happened
– so - make effects explicit, represent system state clearly
Norman’s seven stage model

34. Summary - HCI principles deriving from HIP
 Sutcliffe (1995) suggests seven tentative principles that can
be derived from HIP research:
 Consistency
– Be consistent across tasks. Screens etc.
 Compatibility
– Aim for good fit between user’s expectations and reality of an
interface design
– Have new designs compatible with user’s previous experience
 Predictability
– Interface should suggest to the user what actions are possible
– Hence need appropriate messages, prompts, icons
 Adaptability
– Interface should adapt to its individual user
– Beware though of violating principle of consistency

35. Summary
 Sutcliffe (continued):
– Economy and error prevention
• Aim for minimum number of steps to achieve a task
• Consider dialogue short cuts
• Help user avoid disastrous errors (“Are you sure?
Y/N”)
– User control
• User should be and feel in control - relates to
predictability
• “Undo” is important aspect
– Structure
• Structure interfaces to reduce complexity
• Present only relevant information, in a simple manner
 NB – these are no means the only set of HCI principles!

36.  Norman (2004) suggests four principles of good design:
 Visibility
– state and action alternatives should be visible
 Model
– should be a good conceptual model with consistent
system image
 Mappings
– interface should include good mappings, revealing the
relationships between stages
 Feedback
– user should receive continuous feedback
Summary

37.  variability implies importance of evaluation
 ask yourself, about any interface you develop:
– how well does it fulfil the users’ objectives
– (“task fit”)
– how easy it is to learn and use?
– how effective is it in helping users carry out some work?
 check your affordances
Summary

38. Becta (2008) Emerging Technologies for Learning. Available at
http://webarchive.nationalarchives.gov.uk/20101102103654/http:/research.becta.o
rg.uk/index.php?section=rh&catcode=_re_rp_02&rid=13768
Benyon D (2010) Designing Interactive Systems. Addison-Wesley
Dix, A.J., Finlay J., Abowd G. D., Beale R. (2004) Human-Computer Interaction, 3rd
edition, Prentice-Hall
Norman D (2004) Emotional Design: Why We Love (or Hate) Everyday Things. Basic
Books
Preece J, Rogers Y, Sharp H (2011) Interaction design: beyond human-computer
interaction. Wiley
Raskin J (2000) The humane interface: New Directions for Designing Interactive Systems.
Addison-Wesley
Shneiderman B (2002) Leonardo’s Laptop. MIT Press
Shneiderman B & Plaisant C (2010) Designing the User Interface. Pearson
Smith-Atakan (2006) Human-Computer Interaction. Thomson.
Sutcliffe A G (1995) Human-Computer Interface Design. Macmillan
References