1 Multimedia Design

2  Usability  No matter how powerful or potentially useful a multimedia software application or web site design is, if it can not be worked by the intended user then it is worthless  Communication is at least as important as computation

3 Multimedia Design

4 Iterative Design Evaluate with real users Identify user needs or problems Design a solution Prototype the solution

5 Darn these hooves! I hit the wrong switch again! Who designed these instrument panels, racoons? Multimedia Design

6 The Interactive Cycle Evaluates and understands the display Interprets input events to make changes Data model for the application information Updates to the display Formulates goals and actions, generates inputs Updates to the display Data model changes

7 Gulfs of Understanding  Don Norman has identified two gulfs in a user’s understanding that cause the interactive cycle to break down  Gulf of Evaluation  Gulf of Execution

8 Gulf of Evaluation  Users must interpret what they see on the screen and evaluate it relative to their ultimate goals  There are many ways in which this evaluation might fail:  Ergonomic – Text too small to read Text has poor contrast with background colour

9 Gulf of Evaluation

10 Gulf of Evaluation

11 Gulf of Evaluation

12 Gulf of Evaluation  Design and layout – Items may be ineffectively grouped and so the users misses an important relationship Critical information incorrectly placed All information may appear the same without emphasis or highlights  Relevant information must not only be on the screen, but in a form which is immediately obvious

13 Gulf of Evaluation

14 Gulf of Evaluation

15 Gulf of Execution  This arises when the user does not know what sequence of input events will accomplish the desired goal  There are several things that might cause this gulf  The user does not know what the system can do  The operation of objects on the screen are not obvious e.g buttons, links, scroll bars etc.  Inadequate feedback

16 Gulf of Execution

17 Gulf of Execution

18 Gulf of Execution

19 Consistency and Simplicity  Be consistent in your use of:  Size  Colour  Location  Wording  Function  Sequencing

20 Consistency and Simplicity

21 Consistency and Simplicity

22 Consistency and Simplicity

23 Human Memory Issues  7 items +/- 2  Short term memory is approx. 30 seconds to 2 minutes  User should not need to buffer information from one screen to the next

24  If only I had turned up to the lecture I would know what is on this slide

25 Human Memory Issues  Avoid stacking  Design for task closure  Recognition rather than recall

26 Status Indicators  Whenever the system is performing a potentially lengthy process the user should be given feedback e.g status bar, hourglass, loading screen  System should have response time suitable for task

27 Design Guidelines  General text format rules:  Only use two levels of intensity  Use underlining, bold, inverse video etc. sparingly  Use no more than 3 different fonts  Serif fonts are easier to read, but sans-serif can look more modern  Capitalise as you would in normal sentences

28 Design Guidelines

29 Design Guidelines

30 Design Guidelines  Colour is perhaps the most overused feature in multimedia designs  Use no more than 4 colours on a screen  No more than 7 in an application  Generally blue or black backgrounds with white or yellow characters respectively give the best contrast, but not necessarily the best look!  Blue should not be used for text as it is one of the hardest colours to read

31 Design Guidelines  Consider colour conventions carefully  Red: passion, romance, fire, violence, aggression. Red means stop, warning or forbidden in many cultures  Purple: creativity, mystery, royalty, mysticism, rarity, associated with death in some cultures  Blue: loyalty, security, conservatism, tranquillity, coldness, sadness  Green: nature, fertility, growth, envy, go, environment  Yellow: brightness, illumination, illness, cowardice  Black: power, sophistication, contemporary style, death, morbidity, evil  White: purity, innocence, cleanliness, truth, peace, coldness, sterility

32 Colour Harmony  One of the most challenging aspects of visual design is developing effective colour harmonies that strike a balance between monotony and over stimulation

33 RGB Colour Wheel Primary colours Secondary colours Tertiary colours

34 Design Guidelines  Sound:  Use harsh and soft audio tones for warnings and positive feed back respectively  Sound can add to a site or application, but can also be annoying  It is always a good idea to provide the option to turn the sound off

35 Display Issues  Maintain display inertia  Static objects such as buttons, words and icons that appear on many screens should always appear in the same location  Location, shape and size of objects should be kept as consistent as possible

36 Display Issues  Organise the screen to manage complexity  Eliminate unnecessary information  Use concise wording or easy to recognise icons  User performance suffers when less that 25% of the screen is white space  50% white space is recommended for textual displays  Related information should be grouped logically

37 Fin