Presentation on theme: "User Interfaces. Good interface design A good interface design can help to ensure that users carry out their tasks: – Safely - in the case of a jumbo."— Presentation transcript:
Good interface design A good interface design can help to ensure that users carry out their tasks: – Safely - in the case of a jumbo jet pilot, for example – Effectively - users don’t find they have video’d two hours of Bulgarian clog dancing instead of the Cup Final – Efficiently - users don’t spend 5 minutes trying to find the correct way to insert their cash card and type in their PIN and the amount of cash, and then leave without remembering to extract their card – Enjoyably - a primary school pupil using a program to teach multiplication tables Well designed systems can improve the output of employees, improve the quality of life and make the world a safer and more enjoyable place to live in.
Design Considerations – Who will use the system? Computer professionals or general public? For an educational program, will the users be primary school children or teenagers? Beginners or experienced? Or both? – What tasks is the computer performing? Very repetitive? Requiring skill and knowledge? Do tasks vary greatly from one occasion to the next? A travel agent will require a different interface from an office worker – The computer environment Hazardous (in a lifeboat), noisy (in a factory), or calm and quiet (some offices)? – What is technologically feasible Is it possible to simply dictate a letter to a word processor instead of typing it in?
Interface styles Command line interface; Menus; Natural language; Forms and dialogue boxes; Graphical user interface (GUI).
Menus Several different kinds of menu interface: –Full screen menu Typically the front-end of an application – Pull-down menu As on menu bar at top of most Microsoft applications – Pop-up menu As with short-cut menus available on right-click
Natural language dialogue Advantages: – Most natural form of dialogue for humans — no need for training in a specialised command language; – Extremely flexible and powerful; – The user is free to construct his own commands, frame his own questions, etc.
Natural language dialogue Disadvantages: – People find it difficult to stick to strictly grammatical English; – A well designed ‘artificial language’ can often say the same thing more concisely than ‘natural language’; – A smooth, natural language can easily mislead the naive user into believing the computer is much more intelligent than it actually is.
Forms and dialogue boxes When the user is required to enter data: – Display should be given a title to identify it – The form should not be too cluttered spaces and blanks in a display are important – It should give some indication of how many characters can be entered in each field – User should be given a chance to go back and correct any field before the data is accepted
Forms and dialogue boxes – Items should appear in a logical sequence – Default values should be prewritten onto the form to minimise of data entry – Full exit and ‘help’ facilities should be provided users could enter ‘?’ in a field if they require more information; – Lower-case is neater and easier to read than upper-case; – ‘Attention-getting’ devices such as blinking cursors, high-intensity, reverse video, underlining etc should not be over-used
The WIMP Interface Windows, Icons, Mouse and Pull-down menus –Window is the area on screen through which program or data file is being viewed –Icon is a small picture representing a system item. May be a file, program, command or storage medium. Usually ‘clickable’ –MS Windows allows more than one application to run at a time, and also to move or link data between applications.
Advantages of a common user interface Increased speed of learning; Ease of use; Confidence building for novice users; Increased range of tasks solvable by experienced users; A greater range of software accessible to the average user
Speech Input Ultimate interface would be to be able to speak normally to issue instructions to your computer. Two distinct types of voice recognition systems are emerging: – Command and Control systems Small, tightly-controlled vocab. of technical terms – Large vocabulary dictation system Handle whole sentences – but need considerable processing power and RAM Use probability to select the correct word from a possible set that system has ‘heard’. Considers context and placement in sentence. 70 wpm and around 97% accurate after ‘training’
Speech/Sound output Speech synthesis systems –Words spoken into microphone are recorded by the system –Once the words are in the ‘vocabulary’, output that would normally be printed can then be ‘spoken’ –Sometimes words that are not recognised are spelt out. –Limited use, but possible use in telephone banking or other telecommunications applications