• The interface (or Human Interface) is the aggregate of means by whichpeople – the users – interact with the system.• The user interface is everything the user comes into contact with whileusing system – physically, perceptually and conceptually.
THREE ASPECTS OF USER INTERFACE: The physical aspect- comprise of the devices the user really touches,including the keyboard, mouse, touch screen or keypad. The Perceptual aspects- consist of everything the end user sees, hears,or touches(beyond the physical devices. The conceptual aspects – include everything the user knows aboutusing the system.this include all the problem domain “things” in thesystem the user manipulates, the operation that can be performed andthe procedure followed to carry out operations.
TO DESIGN A BETTER USER INTERFACE, USE THE FOLLOWINGOBJECTIVES:• Match the user interface to the task• Make the user interface efficient• Provide appropriate feedback to users• Generate usable queries.• Improve productivity of knowledge workers.The user interface has two main components:1. Presentation language – the computer-to-human part of the transaction2. Action language – characterizes the human-to-computer portion
GUIDELINES FOR DESIGNING USER INTERFACESAccording to Ben Shneiderman, a leading researcher in HCI(Human-computerInteraction), there are eight general guidelines that are applicable in mostinteractive systems. These are the ff.:1. Strive for consistency – it is imperative to design a consistent-appearing andfunctioning interface. The following should be consistent throughout thesystem:a. The way information is arranged on formsb. The names and arrangement of menu itemsc. The size and shape of iconsd. The sequence followed to carry out tasks2. Enable Frequent Users to use shortcuts. – Users used to work with oneapplication for the whole day so they quickly loose patience with long menusequences and multiple dialog boxes when they know exactly what theywant to do.3. Offer Informative Feedback – each action taken by the user should result tosome type of feedback from the computer so that the users would know theaction was recognized.
4. Design Dialogs to Yield closure – every dialog should be organized in aclear sequence with a beginning, middle and end. . Any well-definedtask has a beginning, middle and end; therefore it is the user’s task onthe computer to also feel this way.5. Offer Simple Error Handling – user errors are costly in both the timeneeded to correct them and the resulting mistakes. That is why, ifpossible, systems designer should prevent the user from makingerrors.6. Permit Easy Reversal of Actions – users should feel that they can exploreoptions and take actions that can be canceled or reversed without anydifficulty.7. Support Internal Locus of Control – Experienced users need to feel thatthey are in-charge of the system and that the system responds to theircommands.8. Reduce Short-Term Memory Load. – People can only remember aboutseven chunks only information at a time.
TYPES OF USER INTERFACEThe different types of user interface are as follows:• Natural Language Interface – this permits users to interact with thecomputer in their everyday or natural language.• Question-and-answer Interface - the computer displays a question tothe user on the display. And the computer then takes action on that inputinformation in a pre-programmed manner, usually by moving to the nextquestions.a dialog box is a type of question-and –answer interface that acts as aquestion and answer interface with another application.• Menu Interface – This type of user interface provides the user with a listof available selections on the computer screen.
• Form-Fill Interface – also referred to as input/output forms, thisinterface consists of onscreen forms or web-based forms that displayfields containing data items or parameters that need to becommunicated to the user• Example of form fill interface of facebook
• Command – Language Interface – this user interface allows the user toenter explicit statements to invoke operations within the system.Example :COPY C:NAMES.DOC A:NAMES.DOC• Graphical User Interface – this types of user interface allows users todirectly manipulate the graphical representation on the screen, whichcan be done with keyboard input, a joystick or a mouse.• Other user interface include pointing devices:• Stylus – a pointed stick that looks like a pen.• Touch-sensitive screens – allow users to use finger in activating the display• Voice recognition and synthesis – allows the users speak to the computerwhile the system is able to recognize the individuals vocal signals, convertthem and store input
TWO MAIN DEVELOPMENTS IN SPEECH RECOGNITION ARE:1. Continuous speech systems that allow for the input of regular text inword processors2. Speaker independence so that any number of people can entercommands or words at a given workstation.Some standards to consider in assessing the interfaces you have chosenare follows:1. The training period necessary for users should be acceptably short.2. Users who are early in their training should be able to enter commandswithout thinking about them or without referring to a help menu ormanual.3. The interface should be faultless so that errors are few and those thatdo occur are not occurring because of poor design.4. The time that users and the system need to recover rom errors shouldbe short.5. Occasional users should be able to study again the system quickly.
GUIDELINES FOR DESIGNING DIALOGDialog is the sequence in which information is displayed to an obtainedfrom a user. A well-designed dialog makes it easier for users to use acomputer and it leads to less frustration with the computer system.There are three main points for designing good dialog and these arefollows:1. Meaningful communication so that the computer understands whatpeople are entering and people understand what the computer ispresenting or requesting.2. Minimal user action3. Standard operation and consistency