Human-Computer Interaction (HCI) is a field of science that studies the design and use of computer technology. HCI focus on interfaces between people and computers and how to design, evaluate, and implement interactive computer systems that satisfy the user. Humans interact with computers in many different ways which means that having a good interface that facilitates that interaction is crucial for our day-to-day activities.
Human Computer Interaction is a basic concern while designing user centered applications. The well designed applications will attract more users towards the application and proficient use of the application. There are certain principles developed to consider when designing applications. There are certain rules to be followed when evaluating an application whether it is portable for the users or not. Let’s have a look at the main areas of the domain
Design rules for interactive systems
Learnability
Learnability means the ease with which new users can begin effective interaction and achieve maximal performance. The learnability of a product can be measured under four areas namely effectiveness, efficiency, satisfaction and errors.
Flexibility
Flexibility means the multiplicity of ways in which the user and system exchange information. There should not be an tough way for user to get information from the system. It also includes the ability of the system to support user interaction for more than one task at a time.
Robustness
Robustness is the level of support provided to the user in determining successful achievement and assessment of goals. It is the extent to which the user can reach the intended goal after recognizing an error in the previous interaction.
Standards and Guideline for Interactive systems
Standards for interactive system design are usually set by national or international bodies to ensure compliance with a set of design rules by a large community. Standards can apply specifically to either the hardware or the software used to build the interactive system.
Shneiderman’s 8 Golden Rules
1.Strive for consistency in action sequences, layout, terminology, command use and so on.
2. Enable frequent users to use shortcuts, such as abbreviations, special key sequences and macros, to perform regular, familiar actions more quickly.
3. Offer informative feedback for every user action, at a level appropriate to the magnitude of the action.
4. Design dialogs to yield closure so that the user knows when they have completed a task.
5. Offer error prevention and simple error handling so that, ideally, users are prevented from making mistakes and, if they do, they are offered clear and informative instructions to enable them to recover.
6. Permit easy reversal of actions in order to relieve anxiety and encourage
exploration, since the user knows that he can always return to the previous state.
7. Support internal locus of control so that the user is in control of the system, which responds to his actions.
8. Reduce short-term memory load by keeping displays simple, consolidating
multiple page displays and providing time for learning action sequences.
Norman’s 7 Principles
1.Use both knowledge in the world and knowledge in the head.
2. Simplify the structure of tasks.
3. Make things visible: bridge the gulfs of Execution and Evaluation.
4. Get the mappings right.
5. Exploit the power of constraints, both natural and artificial.
6. Design for error.
7. When all else fails, standardize.
Evaluation techniques for interactive systems
Evaluation is needed for any systems to know whether the system is functioning according to the requirements, whether it complies with rules and guidelines, whether it has required standards etc. Evaluation should not be thought of as a single phase in the design process. Ideally, evaluation should occur throughout the design life cycle, with the results of the evaluation feeding back into modifications to the design.
Goals of Evaluation
Evaluation has three main goals: to assess the extent and accessibility of the system’s functionality, to assess users’ experience of the interaction, and to identify any specific problems with the system. The design of the system should enable users to perform their intended tasks more easily. In addition to evaluating the system design in terms of its functional capabilities, it is important to assess the user’s experience of the interaction and its impact upon him. The final goal of evaluation is to identify specific problems with the design. These may be aspects of the design which, when used in their intended context, cause unexpected results, or confusion amongst users.
Evaluation through expert analysis
A number of methods have been proposed to evaluate interactive systems through expert analysis. These depend upon the designer, or a human factors expert, taking the design and assessing the impact that it will have upon a typical user. The basic intention is to identify any areas that are likely to cause difficulties because they violate known cognitive principles, or ignore accepted empirical results. These methods can be used at any stage in the development process from a design specification, through storyboards and prototypes, to full implementations, making them flexible evaluation approaches.
Cognitive walkthrough:
In the cognitive walkthrough, the sequence of actions refers to the steps that an interface will require a user to perform in order to accomplish some known task. The evaluators then ‘step through’ that action sequence to check it for potential usability problems. Usually, the main focus of the cognitive walkthrough is to establish how easy a system is to learn. More specifically, the focus is on learning through exploration
Heuristic evaluation:
Heuristic evaluation, developed by Jakob Nielsen and Rolf Molich, is a method for structuring the critique of a system using a set of relatively simple and general heuristics. Heuristic evaluation can be performed on a design specification so it is useful for evaluating early design. The general idea behind heuristic evaluation is that several evaluators independently critique a system to come up with potential usability problems. It is important that there be several of these evaluators and that the evaluations be done independently.
Model-based evaluation
Certain cognitive and design models provide a means of combining design specification and evaluation into the same framework. Design methodologies, such as design rationale, also have a role to play in evaluation at the design stage. Dialog models can also be used to evaluate dialog sequences for problems, such as unreachable states, circular dialogs and complexity.
Evaluation through user participation
User participation in evaluation tends to occur in the later stages of development when there is at least a working prototype of the system in place. This may range from a simulation of the system’s interactive capabilities, without its underlying functionality. These include empirical or experimental methods, observational methods, query techniques, and methods that use physiological monitoring, such as eye tracking and measures of heart rate and skin conductance. There are two types of evaluation namely laboratory studies and field studies.
Laboratory Study: In the first type of evaluation studies, users are taken out of their normal work environment to take part in controlled tests, often in a specialist usability laboratory
Field Study: This type of evaluation takes the designer or evaluator out into the user’s work environment in order to observe the system in action.
Empirical methods: experimental evaluation
One of the most powerful methods of evaluating a design or an aspect of a design is to use a controlled experiment. This provides empirical evidence to support a particular claim or hypothesis. It can be used to study a wide range of different issues at different levels of detail. The evaluator chooses a hypothesis to test, which can be determined by measuring some attribute of participant behavior. A number of experimental conditions are considered which differ only in the values of certain controlled variables
Observational techniques
In this method users are asked to complete a set of predetermined tasks, although, if observation is being carried out in their place of work, they may be observed going about their normal duties. The evaluator watches and records the users’ actions. Consequently users are asked to elaborate their actions by ‘thinking aloud’.
Query techniques
This relies on asking the user about the interface directly. Query techniques can be useful in eliciting detail of the user’s view of a system. They can be used in evaluation and more widely to collect information about user requirements and tasks. There are two main types of query technique: interviews and questionnaires.
Evaluation through monitoring physiological responses
Potentially this type of evaluation will allow the evaluators not only to see more clearly exactly what users do when they interact with computers, but also to measure how they feel. The two areas receiving the most attention to date are eye tracking and physiological measurement.
Universal Design for Interactive Systems
Universal Design is the process of designing products so that they can be used by as many people as possible in as many situations as possible. In the late 1990s a group at North Carolina State University in the USA proposed seven general principles of universal design. They are equitable use, flexibility in use, simple and intuitive to use, perceptual information, tolerance of error, low physical effort, and size and space for approach and use. These seven principles give us a good starting point in considering universal design.
Multi-modal interaction
A system needs to provide information through more than one medium and that can be elicited through multi-modal interaction. Multi-modal interaction covers the five senses namely, sight, sound, touch, taste and smell. Sight. Anyhow, taste and smell are less appreciated, may be they will be needed in future.
Sound in the interface
Sound is an important contributor to usability. There is experimental evidence to suggest that the addition of audio confirmation of modes, in the form of changes in keyclicks, reduces errors. The dual presentation of information through sound and vision supports universal design, by enabling access for users with visual and hearing impairments respectively. It also enables information to be accessed in poorly lit or noisy environments. Sound can convey transient information and does not take up screen space, making it potentially useful for mobile applications.
Touch in the interface
Touch is the only sense that can be used to both send and receive information. The use of touch in the interface is known as haptic interaction. Haptics is a generic term relating to touch, but it can be roughly divided into two areas: cutaneous perception, which is concerned with tactile sensations through the skin; and kinesthetics, which is the perception of movement and position.
Handwriting recognition
Like speech, we consider handwriting to be a very natural form of communication. The idea of being able to interpret handwritten input is very appealing, and handwriting appears to offer both textual and graphical input using the same tools.
Gesture recognition
Gesture is a component of human–computer interaction that has become the subject of attention in multi-modal systems. Being able to control the computer with certain movements of the hand would be advantageous in many situations where there is no possibility of typing, or when other senses are fully occupied. It could also support communication for people who have hearing loss, if signing could be ‘translated’ into speech or vice versa.
Designing Interfaces for diversity
Interfaces are usually designed to cater for the ‘average’ user, but unfortunately this may exclude people who are not ‘average’. There are three main areas to be considered in this context namely disability, age and culture.
Disability:
While designing interfaces in the context of disability, sensory, physical and cognitive impairments should be considered. The systems should be able to provide audible form of interaction to visually impaired people. In the case of people with hearing issues, computer technology can actually enhance communication opportunities for people with hearing loss. Email and instant messaging are great levelers and can be used equally by hearing and deaf users alike. Speech recognition, eye gaze systems can be added in the systems to serve physically impaired people.
Age:
In this context, older people and children have specific needs when it comes to interactive technology. The requirements of the older population may differ significantly from other population groups, and will vary considerably within the population group. Mobile technologies can be used to provide memory aids where there is age-related memory loss. Like older people, children have distinct needs when it comes to technology, and again, as a population, they are diverse. It is therefore important to involve them in the design of interactive systems that are for their use, though this in itself can be challenging as they may not share the designer’s vocabulary or be able to verbalize what they think.
Culture:
Cultural difference is often used synonymously with national differences but this is too simplistic. Factors such as age, gender, race, sexuality, class, religion and political persuasion, may all influence an individual’s response to a system. This is particularly the case when considering websites where often the explicit intention is to design for a particular culture or subculture.
