Human-Computer Interaction
Avoid Common Mistakes
There is a difference between Human-Computer Interaction and a Human-Computer Interface. Interaction involves much more than just the interface.
Physical Factors
Ergonomics is the design and functionality of the environment. The whole office environment should be studied to see how it can be made more comfortable, safe and productive, for example:
Simple measures can be employed, such as persuading staff to tidy their desks or rearranging furniture so that there are no trailing cables, and so on.
Lighting - rooms should be neither over-lit nor under-lit
Furniture - should be comfortable and adjustable. Poorly designed chairs can be responsible for back trouble. Chairs at the wrong height can be responsible for RSI. Short people are legally entitled to ask for a footrest.
Room size and the space that an employee has in a room is covered by EC directives.
Remember that there are legal implications for organisations who do not look after the health and safety of their employees.
Psychological Factors
Understanding how we receive, process and store information can be used to design effective and user-friendly systems.
Humans receive information through the senses, such as:
Vision - the eye is less sensitive to blue light than to red or green, therefore, important information shouldn't be displayed in blue text. Many people are colour blind, especially between red/green, therefore, an interface shouldn't depend on everyone being able to distinguish between colours.
Hearing - Humans respond more quickly to sound than to visual stimuli, therefore, sound effects can be used to give prompts e.g. a sound effect can be played to alert the user that he has received a new message.
Touch - This is important to keyboard and mouse design
Movement - Users may find it difficult to manipulate small objects.
A guiding principle for good interface design is not to contradict our mental image of how things should be e.g. red means danger, green means go.
Designing New Software
Research into Human-Computer Interaction (HCI) involves the study of good software design to see what makes it good. Researchers observe people interacting with computers to see what they find intuitive and what they find confusing.
Good interfaces provide:
Help for novice users
Short-cuts for experienced users
Metaphors or images (e.g. a picture of a printer on a print button)
Consistent behaviour, which makes use of long-term memory e.g. always using F1 for Help or ESC to stop a process. There are certain functions that have become de facto standards.
Clear and helpful error messages.
Uncluttered screens with effective use of colour.
Text v Graphics
A GUI is more appealing than a command line interface but icons cannot always express abstract concepts, therefore, menus are sometimes needed.
Experienced users might prefer a command line interface because they:
Occupy less memory
Need less disk space
Run faster
It can be quicker for an experienced user to type commands than to find icons.
Customising Software
An experienced user might want to hide certain features e.g. unwanted buttons or unnecessary prompts and warnings. Experienced users often want to "turn things off".
Examples of common annoyances are splash screens, "beeps", "Do you really want to do this?" prompts, etc.
Case Study: consider the demise of the Office Assistant!
When Paperclips Attack: http://news.bbc.co.uk/hi/english/sci/tech/newsid_753000/753922.stm
Impact on System Resources
A fancy interface is likely to have an impact on "system resources". This means:
Processing power (processing power is needed to draw the interface, leaving less for the application itself)
Backing Store (a GUI takes up more disk space than a command line interface)
Immediate Access Store (a GUI will hog RAM)
Good link on interface design: http://www.open2.net/ictportal/app/hci/hci.htm