CM160 Interaction Concepts

1
CM160Interaction Concepts

• This session introduces some interaction concepts
  through examples.
• You need to read the supporting notes and
  relevant sections in Preece too.

2
Key assumption understanding the users point of
view is critically important.

• Context
• The situation or setting in which people carry
  out an activity. This includes the physical,
  psychological and the social setting.
• Noisy office, on a building site, quiet bedroom
  study, artefact properties, etc
• Stressed, playful, tired, not fully engaged, etc
• relationships, culture, social expectation.
• Values
• People value some things more than others.
  Different people value different things..
• Intentions
• People have intentions, machines do not. People
  carry out activities on things with some goal in
  mind. People often use whatever comes to hand in
  a situation to help them achieve their goal most
  effectively.
• Motivation
• What drives people to do something. Motivation
  varies between people and between contexts.
• World view
• Peoples background, role and life experience
  shapes their beliefs and expectations.

3
Goals of interaction design

• Usability, Usefulness and User Experience.
• Usability
• To do with the user being able to make use of a
  product.
• CAN it be used? (efficiency, safety, utility,
  learnability, memorability)
• Usefulness
• Do people find it useful? (effectiveness)
• Does it help the user achieve something beyond
  just being able to use the product?
• User experience (pleasure factors)
• To do with what the user feels about the
  interaction e.g.
• Aesthetically pleasing
• Entertaining
• Satisfying
• Motivating
• In a real situation usability, usefulness and
  pleasure factors cannot be so easily
  distinguished.

4
Concepts, principles and guidelines for
interaction design

• Ideas have been taken from computer science and
  from other disciplines e.g psychology,
  anthropology
• Many have proved to be of limited use because
• They did not take account of full context of use
• E.g. hierarchical task analysis cannot easily
  model all the ways a user might handle a task.
• The socio-technical context changed
• E.g it became possible to have a graphical user
  interface on cheap computers.
• They had limited scope
• E.g. modelling human cognition as an
  information processing system
• The rest of this lecture introduces a selection
  of concepts, principles and guidelines that you
  should find immediately useful.
• Further reading Preece, or independent reading
  of your own.

5
Design Principles

• Visibility
• out of sight out of mind
• Feedback
• Letting the user know something has happened
• Constraints
• Limiting what can be done to what is meaningful
  in terms of the task at that stage
• Mapping
• Relationship between words/symbols/objects at the
  interface and their meaning in the users
  experience..
• Consistency
• Obviously. (But consistent with what? Internal or
  external ?)
• Affordance
• What an object invites you to do.
• Scissors invite you to do some cutting with them
  they afford cutting.
• The possibilities for what you can do with
  something is suggested by its form (shape).
• Conceptual model
• should be clear and understandable to the user
  (see later)

6
Design Heuristics

• When design principles are used in practice some
  people call them heuristics.
• In this context heuristics means proceeding to
  a solution by trial and error or by rules that
  are only loosely defined.
• This is meant to convey something a bit more
  than rules of thumb, dos and donts,
  checklists i.e. they should be interpreted in
  context and not blindly followed.
• Heuristics are practical rules to follow, e.g.
  Nielsen gives ten
• always keep users informed about what is going
  on, through providing appropriate feedback in
  reasonable time.
• speak the users language using words, phrases
  and concepts familiar to the user rather than
  (those familiar to the product designer).
• Etc, etclook the rest up yourself. (p.27 and 408)

More
7
More on Design Heuristics

• They could be operationalised to be more specific
  e.g
• always place the quit or exit button at the
  bottom of the first menu list in the
  application.
• However, the more detailed these are the more
  they are likely to be specific to a particular
  context, and so it is important to know WHY a
  rule is being given so you can decide when it
  needs to be broken.
• Operationalised heuristics can turn out to be
  contradictory in a real design situation. This
  highlights a key feature of any design it is
  always about finding a balance of strengths and
  weaknesses (TRADE-OFFS) that the user finds
  acceptable.

8
Conceptual models

• A conceptual model is what you have in mind about
  how something does, or will, work.
• It is a description of the proposed system in
  terms of integrated ideas and concepts about
• what it should do,
• how it should behave,
• and what it should look like
• that will be understood by the users in the
  manner intended. (p.40)
• We are interested in
• Good conceptual models
• and how they get sufficiently aligned in the
  heads of the designer and the user.

9
Case studies

• Panaboard
• University timetable information

10
Metaphors

• People need some familiar reference points when
  getting to grips with something new.
• When someone is trying to explain an idea it
  sometimes helps to present it as if was like a
  more familiar idea. This helps to communicate
  concepts.
• Some designed products exploit metaphors, e.g.
  the office desktop metaphor developed by Xerox
  researchers in the 1970s using
• Careful, evocative choice of names for things and
  actions (file, folder, desktop, etc)
• Recognisable visual representations
• Use and behaviour of objects that was largely
  consistent with the use and behaviour of the more
  familiar things to which the metaphor referred.
• The idea behind using a metaphor as a design
  concept is that
• the user will immediately grasp the meaning and
  use of key components in the product and
• Will be able to figure out what to do most of the
  time by referring to a familiar mental model or
  experience, and will not have to struggle with
  learning a totally new concept or an arbitrary
  set of controls and functions.

More
11
More on Metaphors

• Downsides of metaphors
• They must break down at some point, e.g. a word
  processor is not a typewriter (this metaphor was
  heavily used when word processors were first
  introduced to the mass market). This can cause
  confusion if this breakdown becomes apparent to
  the user too early in her use of the product.
• There are a limited number of universal metaphors
  that are really useful, and some applications may
  not have any that are usefully applicable.
  However this can be offset by drawing on
  metaphors familiar to specialist communities when
  a product is principally designed for use by that
  community (e.g. Photoshop).

12
Relationship between designers and users
concepts of how a system works
Conceptual models Design model the mental
model the designer has of how the system should
work from the users point of view. System
image what the system tells the user about how
it works by its appearance and behaviour Users
model the mental model the user has about how
the system works.
(Norman 1988)
13
Cognitive concepts
Reflective cognition
External cognition
Experiential cognition
Things in the world
You
Knowledge in the World Knowledge
in the Head Distributed Cognition
14
Reflective and Experiential Cognition

• REFLECTIVE COGNITION
• We deal with the situation by thinking the
  problem through, deliberation, reasoning,
  reflection
• Slow
• Requires mental effort its what our attention
  is on
• Errors are mistakes
• we do what we intend
• but our decisions turn out to have been wrong
• E.g. trying to operate University timetable I.S.
• EXPERIENTIAL COGNITON
• We deal with the situation by deploring skills
  and expertise
• Smooth, fast and mentally effortless
• Errors are slips or lapses-
• We dont do what we intend
• The wrong automatic response is triggered by
  the situation
• E.g. slips made when editing text on a word
  processor.

15
External Cognition

• Distributed Cognition
• We dont need to keep all our knowledge in our
  heads we can rely on or arrange for some of it
  being available out in the world when we need
  it.
• Knowledge in the Head
• What we have learned and can recall
• Knowledge in the world
• What we can recognise
• If know we can rely on knowledge in the world we
  dont need to rely on knowledge in the head.
• Example using coins unless we collect coins
  for a hobby, our maybe counterfeit coins we only
  have a minimal recollection of the differences
  between coins, we rely on knowledge in the world
  to supply the detail when required.
• Example
• interaction by typing commands (KiH)
• Interaction by selecting from menu (much more
  KiW)

D.A. Norman
16
Coping with Tasks

• How we cope with complex tasks
• When we perform a task (writing a letter, riding
  a bike or driving a car)
• We rely on not having to use mental effort or
  lower level skills (experiential cognition)
• so that we can focus our mental effort on the
  higher level aspects of the task (reflective
  cognition)
• There is evidence that we have limits to our
  abilities to think things through (reflective
  cognition) - 7 plus or minus two etc
• So when we write a letter we cant have all our
  attention on
• Thinking about holding the pen
• Thinking about how to shape letters
• Thinking about how words are spelled
• Thinking about grammar and phrases.
• Thinking about the things we want to say in the
  letter.
• We rely on not having to think much about most of
  these.

17
Coping with tasks

• How we cope with complex task
• We learn some things through practice so that
  they become part of our repertoire of skills
  that we can call on
• We manage to do complex tasks
• by relying on an hierarchy of experiential
  cognition (skills).
• What skills do you depend on to be able to
• write a letter,
• get from A to B by walking, bus, riding a bike or
  driving a car?
• by relying on an external cognition (knowledge in
  the world).
• What knowledge in the world do you depend on to
• Use your VCR or DVD player
• Send an email
• So that most of our attention (involving
  reflective cognition) can be focused on the
  highest level goals of the task

18
Coping with tasks

• How we cope with complex task
• However, when there is a breakdown e.g. when
  the pencil lead becomes a bit loose and wobbles
  when you write
• Shaping letters becomes more difficult,
• you have to think about it, focus your attention
  on it, you have to resort to using reflective
  cognition rather than experiential cognition for
  that part of the task.
• Consequently, your attention tends to be drawn
  away from the main task of composing the letter.

19
Task Fit

• When a device is not well designed for a task
  users feel
• they are having to spend too much effort on the
  lower level elements of the task.
• that this gets in the way of them giving their
  full attention to the main goal of the task.
• They have to work hard to close the gap between
  what the tool offers and the requirements of the
  task.

20
Good and not so good design

• Examples are everywhere In the home, in cars, at
  work
• telephones, shops, web sites, DVD recorders,
  computer interfaces, etc,etc
• Some web sites specialise in cataloguing bad
  design (see module guide)
• An example

(the mile-high menu bar. source Spolsky)
The Apple menu bar goes right to the top of the
screen. This makes the items in the menu easier
to hit because the pointer can be slammed against
the top of the screen and still be able to select
options.
The MS menu bar is under a title bar. This makes
the active area for selecting menu options much
less.