Human Computer Interaction

Introduction

Human-computer interaction (commonly referred to as HCI) researches the design and use of computer technology, focused on the interfaces between people (users) and computers. Researchers in the field of HCI both observe the ways in which humans interact with computers and design technologies that let humans interact with computers in novel ways

User

By “user”, we may mean an individual user, a group of users working together. An appreciation of the way people’s sensory systems (sight, hearing, touch) relay information is vital. Also, different users form different conceptions or mental models about their interactions and have different ways of learning and keeping knowledge and. In addition, cultural and national differences play a part.

Computer

When we talk about the computer, we’re referring to any technology ranging from desktop computers, to large scale computer systems. For example, if we were discussing the design of a Website, then the Website itself would be referred to as “the computer”. Devices such as mobile phones or VCRs can also be considered to be ―computers‖.

Interaction

There are obvious differences between humans and machines. In spite of these, HCI attempts to ensure that they both get on with each other and interact successfully. In order to achieve a usable system, you need to apply what you know about humans and computers, and consult with likely users throughout the design process. In real systems, the schedule and the budget are important, and it is vital to find a balance between what would be ideal for the users and what is feasible in reality.

Interaction design

Interaction design focuses on creating engaging interfaces with well thought out behaviors. Understanding how users and technology communicate with each other is fundamental to this field. With this understanding, you can anticipate how someone might interact with the system, fix problems early, as well as invent new ways of doing things.

Design rules 

Designing for maximum usability is the goal of interactive systems design. 

Abstract principles offer a way of understanding usability in a more general sense, especially if we can express them within some coherent catalog. 

Design rules in the form of standards and guidelines provide direction for design, in both general and more concrete terms, in order to enhance the interactive properties of the system. 

The essential characteristics of good design are often summarized through ‘golden rules’ or heuristics. 

Design patterns provide a potentially generative approach to capturing and reusing design knowledge.

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.

Principle of Learnability

1.Predictability

Support for the user to determine the effect of future action based on past interaction history.

2.Synthesizability

Support the user to assess the effect of past operations on the current state

3.Familiarity

The extent to which a user’s knowledge and experience in other real-world or computer based domains can be applied when interacting with a new system.

4.Generalizability

Support for the user to extend knowledge of specific interaction within and across applications to other similar situations.

5.Consistency

Likeness in input output behavior arising from similar situations or similar task objectives.

Flexibility

The multiplicity of ways in which the user and system exchange information.

Principles of Flexibility

1.Dialog initiative

Allowing the user freedom from artificial constraints on the input dialog imposed by the system.

2.Multi-threading

Ability of the system to support user interaction pertaining to more than one task at a time.

3.Task migratability

The ability to pass control for the execution of a given task so that it becomes either internalized by the user or the system or shared between them.

4.Substitutivity

Allowing equivalent values of input and out put to be arbitrarily substituted for each other.

5.Customizability

Modifiability of the user interface by the user or the system.

Robustness

The level of support provided to the user in determining successful achievement and assessment of goals.

Principles of robustness

1.Observability

Ability of the user to evaluate the internal state of the system from its perceivable representation.

2.Recoverability

Ability of the user to take corrective action once an error has been recognized.

3.Task conformance

The degree to which the system services support all of the tasks the user wishes to perform and in the way that the user understands them.

4.Responsiveness

How the user perceive the rate of communication with the system.

Standards and Guideline for Interactive systems

Standards

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

A major concern for all of the general guidelines is the subject of dialog styles, which in the context of these guidelines pertains to the means by which the user communicates input to the system, including how the system presents the communication device.

Shneidermans’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. 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

Tests usability and functionality of system

Occurs in laboratory, field and/or in collaboration with users

Evaluates both design and implementation

Should be considered at all stages in the design life cycle

Goals of Evaluation

• assess extent of system functionality
• assess effect of interface on user
• identify specific problems

Evaluation through expert analysis

Cognitive walkthrough

Cognitive walkthroughs are used to examine the usability of a product. They are designed to see whether or not a new user can easily carry out tasks within a given system. It is a task-specific approach to usability (in contrast to heuristic evaluation which is a more holistic usability inspection).

The biggest benefit of a cognitive walkthrough is that it is extremely cost-effective and fast to carry out when compared to many other forms of usability testing. It can also be implemented prior to development during the design phase which can give rapid insight before budget is spent developing an unusable product.

Heuristic evaluation

Heuristic evaluation is a key part of designing a great product that users can easily engage with and find value in their interaction. It is a thorough assessment of a product’s user interface, and its purpose is to detect usability issues that may occur when users interact with a product, and identify ways to resolve them.

The heuristic evaluation process is conducted against a predetermined set of usability principles known as heuristics. The process relies on in-depth tests run by several usability experts at a time.

Model-based evaluation

Model-based evaluation is using a model of how a human would use a proposed system to obtain predicted usability measures by calculation or simulation. These predictions can replace or supplement empirical measurements obtained by user testing. In addition, the content of the model itself conveys useful information about the relationship between the user’s task and the system design.

Evaluation through user participation

Styles of evaluation

Laboratory studies

Users are taken out of their normal work environment to take part in controlled tests, often conducted in a specialist usability laboratory.

Field Studies

Designers or evaluators are taken 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.

Observational techniques

A social research technique that involves the direct observation of phenomena in their natural setting.

This differentiates it from experimental research in which a quasi-artificial environment is created to control for spurious factors, and where at least one of the variables is manipulated as part of the experiment.

Associated with qualitative research.

Query 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.

Types of Query Techniques are

Interviews

Questionnaires

Universal Design for Interactive Systems

Universal Design Principles

1.Equitable Use

Is useful and marketable to people with diverse abilities.

2.Flexibility in Use

Accommodates a wide range of individual preferences and abilities.

3.Simple and Intuitive Use

Easy to understand, regardless of users experience, knowledge, language skills, or current concentration level.

4.Perceptible Information

Communicates necessary information effectively to the user, regardless of ambient conditions or the user’s sensory abilities.

5.Tolerance for Error

Minimizes hazards and the adverse consequences of accidental or unintended actions.

6.Low Physical Effort

Used effectively and comfortably with a minimum of fatigue.

7.Size and Space for Approach and Use

Provides appropriate size and space for approach, reach, manipulation, and use regardless of users body size, posture, or mobility.

Multi-modal interaction

Combination of multiple modalities, or usage of more than one independent channel signals for the interaction between a user and a machine is termed as multimodal human computer interaction system .A multimodal interface acts as a facilitator of human-computer interaction via two or more modes of input. It is easy to use by disabled, illiterate people.

Sound in the interface

The vast majority of computer-based user interfaces that we encounter rely almost totally on the visual medium. However, another medium that is frequently used in interface design is sound. Before discussing how interface designers do and may make use of sound, we will review some of the properties of the audio medium consisting of sound together with the human sense of hearing.

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.

Handwriting recognition

Handwriting is another communication mechanism which we are used to in day-to-day life-a natural form of communication.

Technology

1. Handwriting consists of complex strokes and spaces

2. Captured by digitizing tablet

3. Free-flowing strokes (using a pen) transformed to sequence of coordinates

4. Depending on pressure and movements; Rapid movements-wide spaced dots/ Slow movements -narrowed dots

Information written onto tablets can be displayed, stored, or redisplayed.

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

Disability

Accommodations for physically disabled users should be provided wherever possible. This could include anything from larger buttons to voice activation and touch-screen interfaces.

Age

Note that the senses, particularly hearing and vision, degenerate with age . A good interface takes this fact into consideration, and provides utilities to deal with decreasing physical faculties (i.e. increased volume, text size).

Culture

When deploying an interface in an unfamiliar region, it is imperative that none of the symbols used be offensive in the local culture. As well, no element should be incomprehensible to the locals. Idioms and colloquialisms are to be avoided for this reason. An outside specialist may be required to advise on this aspect.