Human-Computer Interaction & web design

What is prototyping A limited representation of a design that allows users to interact with it and to explore its suitability Allows stakeholders to interact with the envisioned product, gain some experience of using and explore imagined uses Production of an intermediary product to be used as a basis for testing Aim is to save on time and money Aim is to have something that can be tested with real users.

Prototyping cycle
Design
Prototype
Evaluate
Redesign
Done
■ Start with a basic functionality, especially the interface Test the prototype – this will uncover the design errors Correct the errors Repeat until the design is clean.

Goals of prototyping Exploring requirements – market analysis, participatory design Choosing among alternatives – risky or critical features, go/no-go decisions Empirical usability testing – as early as possible, tryout ideas with target users Evolutionary development

3 Main approaches of prototyping Throwaway a small part of the system is developed and then given to the end user to tryout and evaluate. The user provides feedback which can quickly be incorporated into the development of the main system. It functions by providing proof that something can indeed be done in terms of systems and strategies Incremental The final product is built as separate components, one at a time. There is one overall design for the final system, but it is partitioned into independent and smaller components. The final product is then released as a series of products, each subsequent release including one more component
Evolutionary: with this model, processes are made, and throughout the entire course of the design, customers are constantly asked to give feedback for each created prototypes. This is to ensure functionality based on the requirements that customers are looking for in a product or service.
Problems of prototyping:
Time
Planning
Non-functional features

Techniques of prototyping Storyboard - is a graphical depiction of the outward appearance of the intended system, without any accompanying system functionality Computer based simulation - Programming support for simulations means a designer can rapidly build graphical and textual interaction objects and attach some behavior to those objects, which mimics the system’s functionality Wizard of OZ- the designers can develop a limited functionality prototype and enhance its functionality in evaluation by providing the missing functionality through human intervention.
A typical storyboard

DESIGN RULES

Importance of design rules One of the main issue with HCI is, how designers can determine the usability consequences of their design decisions. The solution to that was design rules which a designer follow to increase the usability of the system.
“Poorly designed system can result into serious catastrophe such as the nuclear accident at
Three Mile Island in 1979. This accident occurred because the control panel was
programmed for the light to go off once the computer had sent the signal to close the valve,
which is not the same as when the valve was actually closed. The workers thought the valve
was closed when it was actually opened which resulted into the overheating of the reactor.”

Principles of design rule Learnability – it revolves around the features of an interactive system that allow novice users to understand how to use it at first and then how to attain a maximal level of performance.
Learnability uses various factors to familiarize a user to the new system.
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Predictability: It makes use of the user past knowledge of interacting with a similar system to ease the new system interaction. The notion of predictability deals with the user’s ability to determine the effect of possible interaction to the operations on the system. Another form of predictability has to do with the user’s ability to know which actions can be executed. Example , the transition from windows 7 to windows 8 (start button).
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Synthesizability - is the ability of the user to assess the effect of past operations on the current state. A user expects to see any important change that is occurring while he is interacting with the system. For example, when the user makes a payment he expects to receive a receipt, otherwise he will think that the transaction failed or that he is been scammed. The synthesizability relies on the principle of honesty of the user interface to provide an observable and informative account of occurring change.
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Familiarity - The principle of familiarity is to make use of the new users past experience with other applications. This experience can come from real life situation interaction to interaction with other computer system. For example a danger alert on any system is red, this immediately warns the user that there is a possible threat since red is used in everyday life as such.
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Consistency - Consistency relates to the similarities in behavior arising from alike situations or alike task objectives. It can be expressed in terms of the form of input terms or output responses with respect to the meaning of actions in the conceptual of the system. For example, a user expects a radio button to allow only one choice of the available options.

Principles of design rule Flexibility - refers to the diversity of ways in which the user and the system exchange information. This can be achieved through categorized ways.
a) Dialog initiative - In this communication model, the user is the one to initiate an action on the system. An example, is a tourist using the map system in an airport to obtain direction to his flight fate. The other method is system preemptive where it is the system that initiates an action for the user to respond to. For example a system warning where the user can only click on the ok button.
b) Multithreading - It is the ability to support more than one task of the user system dialog interaction at a time. Concurrent multi-threading allows simultaneous communication of information concerning separate tasks. c) Task migratability - is the ability to transfer the control for task execution between system and user. For example, some task like maintaining an airplane in the correct direction is managed by the computer system but in case of emergency, the pilot can control the direction manually.
d) Substitutivity - It requires that equivalent values can be substituted for each other. It contributes towards flexibility of the system by letting a user choose which action best suits his needs. For example, a user can double click on an icon to open it or can select it and then press enter on the keyboard e)Customizability - It refers to the modifiability of the user interface by the user or the system

Principles of design rule Robustness concerns itself with supporting the user in successfully accomplishing an action with the system and assessment of the action.
a) Observability allows the user to evaluate the internal state of the system by means of its perceivable representation at the interface.
b) Recoverability - It is the ability of a system to recover in case of an error.
c) Responsiveness - deals with the time needed for the system to communicate with the user. In general, short durations and instantaneous response times are desirable.
d) Task conference ensure that the system allows a user to perform task he needs and in an expecting way.

Golden rules and heuristics
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Strive for consistency- Consistent sequences of actions should be required in similar situations identical terminology should be used in prompts, menus, and help screens and consistent commands should be employed throughout.
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Enable frequent users to use shortcuts- such as abbreviations, special key sequences and macros, to perform regular, familiar actions more quickly.
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Offer informative feedback- For every operator action, there should be some system feedback.
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Design dialogs to yield- closure so that the user knows when they have completed a task.
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Offer simple error handling- design the system so the user cannot make a serious error. If an error is made, the system should be able to detect the error and offer simple, comprehensible mechanisms for handling the error.
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Permit easy reversal of actions This feature relieves anxiety, since the user knows that errors can be undone it thus encourages exploration of unfamiliar options.
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Support internal locus of control so that the user is in control of the system, which responds to his actions.
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Reduce short-term memory load- by keeping displays simple, consolidating multiple page displays and providing time for learning action sequences.

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