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© University of Stirling 2011 ITNP43 Interface Design & The World-Wide-Web 1
Preece et al, Chapter 3, 4, 5 Shneiderman, Chapter 5, 8
© University of Stirling 2011 ITNP43 Interface Design & The World-Wide-Web 2
Human Factors
In order to design, it is important to understand the capabilities and limitations of those we are designing for. Key point from this lecture:
– Users share common capabilities, but are individuals with differences which should not be ignored.
Handy slogan:
– Design for the majority, design for the minority
© University of Stirling 2011 ITNP43 Interface Design & The World-Wide-Web 3
Physiology Particular HCI factors to consider:
– Left or right-handed? – Reaction times – Movement – Loss of usual facilities - disabilities
© University of Stirling 2011 ITNP43 Interface Design & The World-Wide-Web 4
Reaction Times
Human reaction times: – Audio signal - 140-160ms – Visual signal - 180-200ms – Pain - 400-500ms
Examples of use:
– Design of video games – Double-click feature on mice
© University of Stirling 2011 ITNP43 Interface Design & The World-Wide-Web 5
Movement
Speed of movement is important for interactive systems. Examples:
– Mouse - keyboard movement (affects choice of which controls operate which actions of the system)
– Time taken to move to a target on screen – Careful arrangement of menu items so that frequent
choices are placed first (and close?)
© University of Stirling 2011 ITNP43 Interface Design & The World-Wide-Web 6
Pointing: Mice and Trackballs
© University of Stirling 2011 ITNP43 Interface Design & The World-Wide-Web 7
Pointing: Fingers and pens Touch screen technology
possibly with a light pen. • Pen has light-sensitive tip, is held up to the computer to
operate, and the pen detects burst of light from the screen Advantages of pen:
– More accurate than touchscreens. – A very direct method of drawing on the screen – Can point directly at the screen more easily
Disadvantages:
– Holding up pen more tiring than desk-based devices. – Fingers are always available!
© University of Stirling 2011 ITNP43 Interface Design & The World-Wide-Web 8
More Pointing Devices Joysticks/controllers
– movement based, or position based – 1-d, 2-d or 3-d devices available
Micropoint – (as in laptops)
Digital pen and tablet – e.g. for handwriting recognition devices, such as Grafitti
on the Palm Pilot. Gyromouse
– pick it up and it tracks your hand movement (3d mouse) Motion sensing
– e.g. Wii, Kinect
© University of Stirling 2011 ITNP43 Interface Design & The World-Wide-Web 9
Assistive Devices Eye movement tracking devices (slow blink to click!), Mice operated by other parts of the body (head, feet, finger, …), again useful for the disabled, or for avoiding (eg) carpal tunnel syndrome
Keyboards
Wide range of keyboards available: – QWERTY keyboard – the “normal” keyboard – Ergonomic keyboard – DVORAK keyboard – keys arranged in a different order – electronic keyboards (Swype technology)
© University of Stirling 2011 ITNP43 Interface Design & The World-Wide-Web 10
Simpler keyboards: – Chord keyboard – small number of
keys, used in combination – At the limit, input may be by a
simple switch – backed up by software
Cognition
Involves understanding, remembering, reasoning, attending, awareness, acquiring skills, creating new ideas. The HCI objective is to understand the interaction between humans and computers in terms of how knowledge is transmitted between the two. Faulkner, Chapts 2 & 3
© University of Stirling 2011 ITNP43 Interface Design & The World-Wide-Web 11
© University of Stirling 2011 ITNP43 Interface Design & The World-Wide-Web 12
Attention Interface designers need to focus attention on the right place:
– Structured information – Information grouped into meaningful parts – Amount of information presented not too much/little
© University of Stirling 2011 ITNP43 Interface Design & The World-Wide-Web 13
Memory Different forms of human memory:
– Short-term memory (working memory) – Permanent long-term memory
Short-term memory is limited
– e.g. approx 5-7 new things can be remembered for about 20 seconds in short-term memory
Chunking – 051594737 versus 051 – 594 – 737 – GGNNTIHIAU versus HUNGATING – GISWWYY versus ??? – RICE?
© University of Stirling 2011 ITNP43 Interface Design & The World-Wide-Web 14
Memory Features appropriate to memory constraints:
– Use of graphical interfaces substantially reduces memory needed
Material is far more easily recognized than recalled
Be consistent with the user’s mental model - use meaningful interfaces:
– command names and icons should be selected carefully
What is meaningfulness? – Context in which used – Task for which it is being used – Form of the representation (icon?) – Underlying concept being represented
© University of Stirling 2011 ITNP43 Interface Design & The World-Wide-Web 15
Example 1: Icons (bad)
Zoc (a communications application): – Send – Send without carriage returns – Send with quotes
© University of Stirling 2011 ITNP43 Interface Design & The World-Wide-Web 16
Example 2: Easy CD Writer (bad)
© University of Stirling 2011 ITNP43 Interface Design & The World-Wide-Web 17
Example 3: Image Preview (good)
© University of Stirling 2011 ITNP43 Interface Design & The World-Wide-Web 18
Perception Input from the different senses
– Auditory Perception – Haptic (Touch) Perception – Visual Perception
We need to understand how the input information is perceived by humans, and what difference this makes to us when considering good HCI.
© University of Stirling 2011 ITNP43 Interface Design & The World-Wide-Web 19
Auditory Perception Uses of non-speech sounds include the following:
– Attracting attention e.g. to an emergency situation that the user should respond to
– Status information e.g. quiet background noise can monitor the progression of a file downloading
– Confirmation sound associated with an action, e.g. button press, file deletion, sent message
© University of Stirling 2011 ITNP43 Interface Design & The World-Wide-Web 20
Haptic Perception As far as use in computing design goes... Touch is an important source of feedback when using devices:
– Pressing buttons – Using a keyboard (raised dots on the ‘f’ and ‘j’ keys) – Hand-held devices (e.g. phones) – Specialist devices
For users with other senses impaired, touch may be a vital additional source of information (e.g. braille)
© University of Stirling 2011 ITNP43 Interface Design & The World-Wide-Web 21
Visual Perception Three main aspects:
– Size/depth – Brightness – Colour
© University of Stirling 2011 ITNP43 Interface Design & The World-Wide-Web 22
Perception of Size/Depth
Our two eyes give us 3D vision, but we can see in 3D even with one eye closed.
– In order for us to perceive the 3D world, our brains have substantial built-in ways of interpreting 2D images as 3D.
– Designers commonly make use of these. Example...
© University of Stirling 2011 ITNP43 Interface Design & The World-Wide-Web 23
Example: 3-D Effects for Highlighting
© University of Stirling 2011 ITNP43 Interface Design & The World-Wide-Web 24
Perception of Size/Depth
These same automatic interpretations are responsible for many illusions.
– Illusions are very good for revealing the interpretations we place on visual information.
– If you are interested in optical illusions visit ( the last is all one URL)
www.youramazingbrain.org/supersenses/ www.eyetricks.com psylux.psych.tu-dresden.de/i1/kaw/diverses%20Material/www.illusionworks.com/index.html
© University of Stirling 2011 ITNP43 Interface Design & The World-Wide-Web 25
Size/Depth Perception
Big monster chasing a little monster?
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