Human computer interaction

Human-computer interaction (HCI) is a multidisciplinary field of study focusing on the design of computer technology and, in particular, the interaction between humans (the users) and computers. HCI studies the design and use of computer technology, focused on the interfaces between people (users) and computers. Researchers in the field of HCI observe the ways in which humans interact with computers and design technologies that let humans interact with computers in novel ways.

Design rules for interactive systems

Learnability

Learnability is a quality of products and interfaces that allows users to quickly become familiar with them and able to make good use of all their features and capabilities. Learnability is one component of usability and is often heard in the context of user interface or user experience (UX) design, as well as usability and user acceptance testing.

A very learnable interface or product is sometimes said to be intuitive because the user can immediately grasp how to interact with the system. First-time learnability refers to the degree of ease with which a user can learn a newly-encountered system without referring to documentation, such as manuals, user guides or FAQ (frequently-asked questions) lists. One element of first-time learnability is discoverability, which is the degree of ease with which the user can find all the elements and features of a new system when they first encounter it.

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 and ability of user to evaluate the internal state of the system from its perceivable representation. 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 is 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. Guideline is a Guideline is a rule about designing interactive systems.

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

What is Evaluation?

Evaluation is a systematic determination of a subject’s merit, worth and significance, using criteria governed by a set of standards. It can assist an organization, program, design, project or any other intervention or initiative to assess any aim, realizable concept/proposal, or any alternative, to help in decision-making; or to ascertain the degree of achievement or value in regard to the aim and objectives and results of any such action that has been completed. The primary purpose of evaluation, in addition to gaining insight into prior or existing initiatives, is to enable reflection and assist in the identification of future change.

Goals of Evolution

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 system’s functionality is important in that it must accord with the user’s requirements. In other words, the design of the system should enable users to perform their intended tasks more easily. This includes not only making the appropriate functionality available within the system, but making it clearly reachable by the user in terms of the actions that the user needs to take to perform the task. It also
involves matching the use of the system to the user’s expectations of the task.

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. The techniques we have considered so far concentrate on evaluating a design or system through analysis by the designer, or an expert evaluator, rather than testing with actual users. However, useful as these techniques are for filtering and refining the design, they are not a replacement for actual usability testing with the people for whom the system is intended: the users. In this section we will look at a number of different approaches to evaluation through user participation.

Styles of Evolution

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.

Styles of evaluation

1. Laboratory studies — users are taken out of their normal work environment to take part in controlled tests, often in a specialist usability laboratory.
2. Field studies — This 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. Any experiment has the same basic form. 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. Any changes in the behavioral measures are attributed to the different conditions. Within this basic form there are a number of factors that are important to the overall reliability of the experiment, which must be considered carefully in experimental design. These include the participants chosen, the variables tested and manipulated, and the hypothesis tested.

Observational Techniques

A popular way to gather information about actual use of a system is to observe users interacting with it. Usually they 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. Simple observation is seldom sufficient to determine how well the system meets the users’ requirements since it does not always give insight into the their decision processes or attitude.

Query techniques

These techniques 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. It may be difficult to get accurate feedback about alternative designs if the user has not experienced them. There are two main types of query technique: Interviews, 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 Principles

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,

1. equitable use

2. flexibility in use

3. simple and intuitive to use

4.perceptual information

5.tolerance of error

6. low physical effort

7.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. 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. There are two types of sound that we could use: speech and non-speech.

Touch in the interface

Touch is the only sense that can be used to both send and receive information. Although it is not yet widely used in interacting with computers, there is a significant research effort in this area and commercial applications are becoming available. 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. Both are useful in interaction but they require different technologies.

Handwriting recognition

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. There are problems associated with the use of handwriting as an input medium, however, and in this section we shall consider these. The main technology used to capture handwriting is the digitizing tablet which has been refined by incorporating a thin screen on top to display the information, producing electronic paper. Such devices are small and portable enough to be realistically useful in handheld organizers such as the Apple Newton.

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’. As we saw in the introduction to this chapter, people are diverse and there are many factors that must be taken into account if we are to come close to universal design. In this section, we will consider briefly some of these factors and the particular challenges that each raises. We will consider three key areas: disability, age and culture.

01. Designing for users with disabilities

1.Users with Disabilities

● visual impairment (The sensory impairment that has attracted the most attention from researchers, perhaps because it is potentially also one of the most debilitating as far as interaction is concerned, is visual impairment. The rise in the use of graphical interfaces reduces the possibilities for visually impaired users.)

● hearing impairment (Compared with a visual disability where the impact on interacting with a graphical interface is immediately obvious, a hearing impairment may appear to have little impact on the use of an interface. After all, it is the visual not the auditory channel that is predominantly used. To an extent this is true, and computer technology can actually enhance communication opportunities for people with hearing loss.)

● physical impairment (Users with physical disabilities vary in the amount of control and movement that they have over their hands, but many find the precision required in mouse control difficult. Speech input and output is an option for those without speech difficulties.)

● speech impairment (For users with speech and hearing impairments, multimedia systems provide a number of tools for communication, including synthetic speech and text-based communication and conferencing systems.)

● dyslexia (Users with cognitive disabilities such as dyslexia can find textual information difficult. Speech input and output and spelling correction facilities can help those users.)

● autism (Autism affects a person’s ability to communicate and interact with people around them and to make sense of their environment.)

2.Designing for different age groups

The other area of diversity that impact is age. In particular, older people and children have specific needs when it comes to interactive technology.

older people e.g. disability aids, memory aids, communication tools to prevent social isolation

children e.g. appropriate input/output devices, involvement in design process

3. Designing for cultural differences

The 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.