Human Computer Interaction

In this article, we discuss about Design rules, Evaluation technique and Universal design about Interactive system.

We require design rules, which are rules a designer can follow in order to increase the usability of the eventual software product. We can classify these rules along two dimensions, based on the rule’s authority and generality. By authority, we mean an indication of whether or not the rule must be followed in design or whether it is only suggested. By generality, we mean whether the rule can be applied to many design situations or whether it is focussed on a more limited application situation. Design rules for interactive systems can be supported by psychological, cognitive, ergonomic, sociological, economic or computational theory, which may or may not have roots in empirical evidence. The most abstract design rules are general principles, which can be applied to the design of an interactive system in order to promote its usability.

The principles we present are first divided into three main categories:

· Learnability — the ease with which new users can begin effective interaction and achieve maximal performance. Learnability concerns the features of the interactive system that allow novice users to understand how to use it initially and then how to attain a maximal level of performance

· Flexibility — the multiplicity of ways in which the user and system exchange information. Flexibility refers to the multiplicity of ways in which the end-user and the system exchange information.

· Robustness — the level of support provided to the user in determining successful achievement and assessment of goals. In a work or task domain, a user is engaged with a computer in order to achieve some set of goals. The robustness of that interaction covers features that support the successful achievement and assessment of the goals.

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.

Ex. The UK Ministry of Defence has published an Interim Defence Standard 00–25 on Human Factors for Designers of Equipment, produced in 12 parts:

Part 1 Introduction

Part 2 Body Size

Part 3 Body Strength and Stamina

Part 4 Workplace Design

Part 5 Stresses and Hazards

Part 6 Vision and Lighting

Part 7 Visual Displays

Part 8 Auditory Information

Part 9 Voice Communication

Part 10 Controls

Part 11 Design for Maintainability

Part 12 Systems

And also following are the one of example of guidelines of the interactive system.

The basic categories of the Smith and Mosier guidelines are:

Data Entry

Data Display

Sequence Control

User Guidance

Data Transmission

Data Protection

Shneiderman’s Eight Golden Rules of Interface Design

Shneiderman’s eight golden rules provide a convenient and succinct summary of the key principles of interface design.

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 Seven Principles

Norman’s seven principles provide a useful summary of his user-centered design philosophy.

1. Use both knowledge in the world and knowledge in the head. People work better when the knowledge they need to do a task is available externally — either explicitly or through the constraints imposed by the environment. But experts also need to be able to internalize regular tasks to increase their efficiency. So systems should provide the necessary knowledge within the environment and their operation should be transparent to support the user in building an appropriate mental model of what is going on.

2. Simplify the structure of tasks. Tasks need to be simple in order to avoid complex problem solving and excessive memory load. There are a number of ways to simplify the structure of tasks. One is to provide mental aids to help the user keep track of stages in a more complex task. Another is to use technology to provide the user with more information about the task and better feedback. A third approach is to automate the task or part of it, as long as this does not detract from the user’s experience. The final approach to simplification is to change the nature of the task so that it becomes something more simple. In all of this, it is important not to take control away from the user.

3. Make things visible: bridge the gulfs of execution and evaluation. The interface should make clear what the system can do and how this is achieved, and should enable the user to see clearly the effect of their actions on the system.

4. Get the mappings right. User intentions should map clearly onto system controls. User actions should map clearly onto system events. So it should be clear what does what and by how much. Controls, sliders and dials should reflect the task — so a small movement has a small effect and a large movement a large effect.

5. Exploit the power of constraints, both natural and artificial. Constraints are things in the world that make it impossible to do anything but the correct action in the correct way. A simple example is a jigsaw puzzle, where the pieces only fit together in one way. Here the physical constraints of the design guide the user to complete the task.

6. Design for error. To err is human, so anticipate the errors the user could make and design recovery into the system.

7. When all else fails, standardize. If there are no natural mappings then arbitrary mappings should be standardized so that users only have to learn them once. It is this standardization principle that enables drivers to get into a new car and drive it with very little difficulty — key controls are standardized. Occasionally one might switch on the indicator lights instead of the windscreen wipers, but the critical controls (accelerator, brake, clutch, steering) are always the same.

Evaluation techniques for interactive systems

Evaluation is a test our systems to ensure that they actually behave as we expect and meet user requirements.

Evaluation has three main goals.

to assess the extent and accessibility of the system’s functionality.

to assess users’ experience of the interaction.

to identify any specific problems with the system.

Evaluation should occur throughout the design process. In particular, the first evaluation of a system should ideally be performed before any implementation work has started.

Expert analysis 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

We will consider four approaches to expert analysis: cognitive walkthrough, heuristic evaluation, the use of models and use of previous work.

· The origin of the cognitive walkthrough approach to evaluation is the code walkthrough familiar in software engineering. Walkthroughs require a detailed review of a sequence of actions. In the code walkthrough, the sequence represents a segment of the program code that is stepped through by the reviewers to check certain characteristics.

· A heuristic is a guideline or general principle or rule of thumb that can guide a design decision or be used to critique a decision that has already been made. Heuristic evaluation can be performed on a design specification so it is useful for evaluating early design. But it can also be used on prototypes, storyboards and fully functioning systems.

· A third expert-based approach is the use of models. Certain cognitive and design models provide a means of combining design specification and evaluation into the same framework.

· A final approach to expert evaluation exploits this inheritance, using previous results as evidence to support (or refute) aspects of the design. It is expensive to repeat experiments continually and an expert review of relevant literature can avoid the need to do so.

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.

Laboratory studies and Field studies are the two evaluation styles. Laboratory studies: users are taken out of their normal work environment to take part in controlled tests, often in a specialist usability laboratory. Field studies takes the designer or evaluator out into the user’s work environment in order to observe the system in action. Again this approach has its pros and cons.

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.

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.

Another set of evaluation 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. They embody the philosophy that states that the best way to find out how a system meets user requirements is to ‘ask the user’. They can be used in evaluation and more widely to collect information about user requirements and tasks.

One of the problems with most evaluation techniques is that we are reliant on observation and the users telling us what they are doing and how they are feeling. What if we were able to measure these things directly? Interest has grown recently in the use of what is sometimes called objective usability testing, ways of monitoring physiological aspects of computer use. Potentially this will allow us not only to see more clearly exactly what users do when they interact with computers, but also to measure how they feel.

Universal Design for interactive technique

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’.

Universal design principals are the,

· Equitable use

· Flexibility in use

· Simple and intuitive to use

· Perceptible information

· Tolerance for error

· Physical effort

· Size and space for approach and use

Providing access to information through more than one mode of interaction is an important principle of universal design. Such design relies on multi-modal interaction. There are five senses: sight, sound, touch, taste and smell.

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. Video games offer further evidence, since experts tend to score less well when the sound is turned off than when it is on; they pick up vital clues and information from the sound while concentrating their visual attention on different things.

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 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 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.

Design for diversity

We will consider three key areas: disability, age and culture.

It is estimated that at least 10% of the population of every country has a disability that will affect interaction with computers. Employers and manufacturers of computing equipment have not only a moral responsibility to provide accessible products, but often also a legal responsibility. In many countries, legislation now demands that the workplace must be designed to be accessible or at least adaptable to all — the design of software and hardware should not unnecessarily restrict the job prospects of people with disabilities.

People differ along a range of sensory, physical and cognitive abilities. However, there are other areas of diversity that impact upon the way we design interfaces. One of these is age. In particular, older people and children have specific needs when it comes to interactive technology.

Cultural difference is often used synonymously with national differences but this is too simplistic. Whilst there are clearly important national cultural differences, other 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.