The Design Process A bluffer’s guide to interface design A ‘proper’ Design process

Bluff your way as an interface designer Five core goals User profiling Eight golden rules

Five core goals Time to learn Speed of performance once learned Rate of errors Retention over time Satisfaction

Profiling users - understand diversity “Know thy user” - write down a profile including: age, gender, physical ability, experience, culture, language, environment of use How experienced are your users? novice or first-time users knowledgeable intermittent users expert frequent users

Is there only one type of user for your system? Write down a profile of tasks for each kind of user: hierarchical task decomposition assess relative frequencies of tasks The user is almost certainly not you!!

Library Scenario Your local library has received funding from the city council to place a PC in its foyer for looking up bus timetables. This will enable visitors to find out when buses for their town stop at the library There are currently standard paper-based bus timetables available in the foyer. However, library users who visit by bus have complained that these are difficult to read and not specific enough to the library.

Schneiderman’s eight golden rules 1. Strive for consistency 2. Enable frequent users to use shortcuts 3. Offer informative feedback 4. Design dialogue to yield closure 5. Offer error prevention and simple handling 6. Permit easy reversal of actions 7. Support internal locus of control 8. Reduce short term memory load

‘Proper’ interface design: the design process Three key activities Understand user requirements (various methods) Prototype & build the interface (programming environments software tools) Evaluate & refine (expert reviews, usability testing and experiments) But these may be interwoven through ‘iterative design’

The Traditional Waterfall Model of Systems Design Requirements Design Implement Test Maintain

The Human Centred Design Cycle Plan the user-centred process Understand and specify the context of use Specify the user and organisational requirements Produce Design Solutions Evaluate Designs Against User Requirements Meets requirements Context: Users, tasks, hardware, software, materials, physical and social environments From: ISO Human Centred Design Process for Interactive Systems (1999)

Putting them together: user- centred & iterative system design USER Requirements Design Test Implement Maintain Task Computers Environment Iterations

Different perspectives on design User requirements Individual and cognitive perspective Draws on psychology Focuses on individual capabilities, task performance and dialogue Social and organisational perspective Draws on sociology and management Focuses on organisational fit, environment, collaboration and legal and ethical issues Design perspective Draws on art and design Considers aesthetic, cultural and marketing aspects of interaction design