Importance of the Interactive System Design
By: Sunanda Karunajeewa
Tags: Evaluation Techniques, Interactive Systems, Universal Design, Design Rule, Hcl

Interactive design is a user-oriented field of study that focuses on meaningful communication of media through cyclical and collaborative processes between people and technology. Successful interactive designs have simple, clearly defined goals, a strong purpose, and an intuitive screen interface.

Design rules for interactive systems

1)Principles of Learnability

The ease with which new users can begin effective interaction and achieve maximal performance.

Predictability

support for the user to determine the effect of future action based on past interaction history. Predictability means that interaction design should set accurate expectations about what will happen before the user taps, swipes, or clicks on something.

Synthesizability

support for the user to assess the effect of past operations on the current state. Immediate honesty and eventual honesty are two aspects of synthesizability. These concepts usually apply to the ability of the interactive system to provide the user with measurable and informative notification of changes in the operating state of the system.

Familiarity

The familiarity principle is concerned with the ability of an interactive system to allow a user to map prior experiences, either real-world or gained from interaction with other systems, onto the features of a new system. 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.

Generalizability

This theory of interactive design offers support for users to expand knowledge of particular experiences to new, but similar circumstances within and across applications.

Consistency

Consistency is important for fostering generalizability and is perhaps one of the most commonly used design concepts in the design of user interfaces. There should always be clear use of labels and icons and the same icons and labels should be used.

2)Principles of Flexibility

Consider a setting with multiple demand classes that are served by a set of resources. When each resource is limited to serving only one demand class, we can often have a situation where some resources are under-utilized and idle, while others are over-utilized and not able to meet the demand. One tactic for dealing with this situation is to make each resource more flexible so that it can serve more than one demand class. But how much flexibility should each resource have and what is the best way to deploy flexibility across the resources? This chapter shows that when done right, limited flexibility can provide almost the same level of benefits as complete flexibility.

Dialog initiative

The dialog is said to be machine preemptive when the scheme regulates the dialog flow. Conversely, the dialog is said to be preemptive for the user when the flow is managed by the user.

Multi-threading

A thread may be considered a part of a dialog within a user interface that allows a task to be completed. Multi-threading provides support for several tasks to be performed at once within an interface.

Task migratability

Task migration requires transferring responsibility between the user and the system for the execution of tasks. One clear example of this is a computerized spell checker.

Substitutivity

Substitutivity offers users alternative ways of specifying input or viewing output. For example, a drawing package may allow the start and end coordinates of a line to be specified, conversely, the same system may allow the line to be drawn first, and the system indicates the endpoint coordinates.

Customizability

The user interface should be able to support individual preferences. For example, standard control bars in MS Word can be changed as needed.

3)Principles of Robustness

The level of support provided the user in determining successful achievement and assessment of goal-directed behavior.

Observability

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

Recoverability

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

Responsiveness

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

Task conformance

The degree to which system services support all of the user’s tasks.

4)Standards and Guideline for Interactive systems

Set by national or international bodies to ensure compliance by a large community of designer’s standards require sound underlying theory and slowly changing technology. Hardware standards more common than software with high authority and low level of detail. ISO 9241 defines usability as effectiveness, efficiency, and satisfaction with which users accomplish tasks.

5)8 Golden Rules of Interface Design

Ben Shneiderman (born August 21, 1947) is an American computer scientist and professor at the University of Maryland Human-Computer Interaction Lab. His work is comparable to other contemporary design thinkers like Don Norman and Jakob Nielsen. In his popular book “Designing the User Interface: Strategies for Effective Human-Computer Interaction”, Shneiderman reveals his eight golden rules of interface design:

Strive for consistency by utilizing familiar icons, colors, menu hierarchy, call-to-actions, and user flows when designing similar situations and sequence of actions. Standardizing the way information is conveyed ensures users are able to apply knowledge from one click to another; without the need to learn new representations for the same actions. Consistency plays an important role by helping users become familiar with the digital landscape of your product so they can achieve their goals more easily.

by utilizing familiar icons, colors, menu hierarchy, call-to-actions, and user flows when designing similar situations and sequence of actions. Standardizing the way information is conveyed ensures users are able to apply knowledge from one click to another; without the need to learn new representations for the same actions. Consistency plays an important role by helping users become familiar with the digital landscape of your product so they can achieve their goals more easily. Enable frequent users to use shortcuts. With increased use comes the demand for quicker methods of completing tasks. For example, both Windows and Mac provide users with keyboard shortcuts for copying and pasting, so as the user becomes more experienced, they can navigate and operate the user interface more quickly and effortlessly.

With increased use comes the demand for quicker methods of completing tasks. For example, both Windows and Mac provide users with keyboard shortcuts for copying and pasting, so as the user becomes more experienced, they can navigate and operate the user interface more quickly and effortlessly. Offer informative feedback. The user should know where they are at and what is going on at all times. For every action, there should be appropriate, human-readable feedback within a reasonable amount of time. A good example of applying this would be to indicate to the user where they are at in the process when working through a multi-page questionnaire. A bad example we often see is when an error message shows an error code instead of a human-readable and meaningful message.

The user should know where they are at and what is going on at all times. For every action, there should be appropriate, human-readable feedback within a reasonable amount of time. A good example of applying this would be to indicate to the user where they are at in the process when working through a multi-page questionnaire. A bad example we often see is when an error message shows an error code instead of a human-readable and meaningful message. Design dialogue to yield closure. Don’t keep your users guessing. Tell them what their action has led them to. For example, users would appreciate a “Thank You” message and a proof of purchase receipt when they’ve completed an online purchase.

Don’t keep your users guessing. Tell them what their action has led them to. For example, users would appreciate a “Thank You” message and a proof of purchase receipt when they’ve completed an online purchase. Offer simple error handling. No one likes to be told they’re wrong, especially your users. Systems should be designed to be as fool-proof as possible, but when unavoidable errors occur, ensure users are provided with simple, intuitive step-by-step instructions to solve the problem as quickly and painlessly as possible. For example, flag the text fields where the users forgot to provide input in an online form.

No one likes to be told they’re wrong, especially your users. Systems should be designed to be as fool-proof as possible, but when unavoidable errors occur, ensure users are provided with simple, intuitive step-by-step instructions to solve the problem as quickly and painlessly as possible. For example, flag the text fields where the users forgot to provide input in an online form. Permit easy reversal of actions. Designers should aim to offer users obvious ways to reverse their actions. These reversals should be permitted at various points whether it occurs after a single action, a data entry or a whole sequence of actions.

Designers should aim to offer users obvious ways to reverse their actions. These reversals should be permitted at various points whether it occurs after a single action, a data entry or a whole sequence of actions. Support internal locus of control. Allow your users to be the initiators of actions. Give users the sense that they are in full control of events occurring in the digital space. Earn their trust as you design the system to behave as they expect.

Allow your users to be the initiators of actions. Give users the sense that they are in full control of events occurring in the digital space. Earn their trust as you design the system to behave as they expect. Reduce short-term memory load. Human attention is limited and we are only capable of maintaining around five items in our short-term memory at one time. Therefore, interfaces should be as simple as possible with proper information hierarchy and choosing recognition over recall. Recognizing something is always easier than recall because recognition involves perceiving cues that help us reach into our vast memory and allowing relevant information to surface.

6)Norman’s 7 Principles

Donald Norman, one of the most notable researchers in the field of human-computer interaction and user-centered design, provides seven key design principles to keep in mind while designing any interface. Norman’s idea is that devices, computers, and interfaces should function correctly and be intuitive and easy to use. The six principles that revolve around this idea are:

1. Use both pieces of 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 system

What is evaluation?

Evaluation is a process that critically examines a program. It involves collecting and analyzing information about a program’s activities, characteristics, and outcomes. Its purpose is to make judgments about a program, to improve its effectiveness, and/or to inform programming decisions.

Goals of evaluation

1. Assess the extent of system functionality -The design of the system should allow users to more easily perform their intended tasks. This means not only making available the required features inside the system but also making it easily accessible.

2. Assess the effect of interface on the user -It’s necessary to analyze the user’s interaction experience and its effect on the user. This involves considering things such as how simple the system is to understand, its accessibility, and the satisfaction of the user with it.

3. Identify specific problems -These may be aspects of the design n which, when used in their intended context, cause unexpected results, or confusion amongst users. Both the functionality and usability of the design are related to this.

Evaluation through expert analysis

In particular, the first evaluation of a system should ideally be performed before any implementation work has started. Some 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. They are also relatively cheap since they do not require user involvement. However, they do not assess the actual use of the system, only whether or not a system upholds accepted usability principles.

The cognitive walkthrough is a usability evaluation method in which one or more evaluators work through a series of tasks and ask a set of questions from the perspective of the user. The focus of the cognitive walkthrough is on understanding the system’s learnability for new or infrequent users.

Heuristic evaluation is a process where experts use rules of thumb to measure the usability of user interfaces in independent walkthroughs and report issues. Evaluators use established heuristics (e.g., Nielsen-Molich’s) and reveal insights that can help design teams enhance product usability from early in development.

Model-based evaluation is using a model of how a human would use a proposed system to ob- tain predicted usability measures by calculation or simulation. These predictions can replace or supplement empirical measurements obtained by user testing.

Using Previous Studies in Evaluation is Experimental psychology and human-computer interaction between them possess a wealth of experimental results and empirical evidence. Some of this is specific to a particular domain, but much deals with more generic issues and applies in a variety of situations. Examples of such issues are the usability of different menu types, the recall of command names, and the choice of icons. 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. It should be noted that experimental results cannot be expected to hold arbitrarily across contexts. The reviewer must therefore select evidence carefully, noting the experimental design is chosen, the population of participants used, the analyses performed and the assumptions made.

Evaluation through user participation

1. Styles of evaluation -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. There are two types of evaluation studies; Laboratory studies (Users are taken out of their normal work environment to take part in controlled tests, often in a specialist usability laboratory) and Field studies (Takes the designer or evaluator out into the user’s work environment in order to observe the system in action).

2. Empirical methods: experimental evaluation-To support a particular claim or hypothesis, this offers empirical proof. At various levels of details, it can be used to analyze a wide variety of different issues. Also, this is one of the most powerful methods of evaluating a design or an aspect of a design is to use a controlled experiment. There are a number of factors that must be considered carefully in experimental design such as Participants, Variables tested and manipulated, Hypothesis tested, and Experimental design.

3. Observational techniques -A popular way to gather information about the 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 the observation is being carried out in their place of work, they may be observed going about their normal duties. Some of the techniques used to evaluate systems by observing user behavior are; Think Aloud, Cooperative evaluation, Protocol analysis, Automated analysis, and Post-task walkthroughs.

4. 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. The advantage of such methods is that they get the user’s viewpoint directly and may reveal issues that have not been considered by the designer. There are two main types of query technique: interviews and questionnaires.

Evaluation through monitoring physiological responses

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. The two areas receiving the most attention to date are eye-tracking and physiological measurement.

When it comes to eye tracking, modern systems use a head-mounted camera to monitor the eye. Eye movements are believed to reﬂect the amount of cognitive processing a display requires. So measuring not only where people look, but also their patterns of eye movement may tell us which areas of a screen they are ﬁnding easy or difﬁcult to understand.

The emotional response is closely tied to physiological changes. These include changes in heart rate, breathing, and skin secretions. Measuring these physiological responses may therefore be useful in determining a user’s emotional response to an interface.

Universal Design for Interactive Systems

Universal Design Principles

The 7 Principles of Universal Design were developed in 1997 by a working group of architects, product designers, engineers, and environmental design researchers, led by the late Ronald Mace in the North Carolina State University. The purpose of the Principles is to guide the design of environments, products, and communications. According to the Center for Universal Design in NCSU, the Principles “may be applied to evaluate existing designs, guide the design process and educate both designers and consumers about the characteristics of more usable products and environments.”

Equitable Use

The design is useful and marketable to people with diverse abilities. Provide the same means of use for all users: identical whenever possible; equivalent when not. Avoid segregating or stigmatizing any users. Provisions for privacy, security, and safety should be equally available to all users. Make the design appealing to all users.

Flexibility in Use

The design accommodates a wide range of individual preferences and abilities. Provide choice in methods of use. Accommodate right- or left-handed access and use. Facilitate the user’s accuracy and precision. Provide adaptability to the user’s pace.

Simple and Intuitive Use

Use of the design is easy to understand, regardless of the user’s experience, knowledge, language skills, or current concentration level. Eliminate unnecessary complexity. Be consistent with user expectations and intuition. Accommodate a wide range of literacy and language skills. Arrange information consistent with its importance. Provide effective prompting and feedback during and after task completion.

Perceptible Information

The design communicates necessary information effectively to the user, regardless of ambient conditions or the user’s sensory abilities. Use different modes (pictorial, verbal, tactile) for redundant presentation of essential information. Provide adequate contrast between essential information and its surroundings. Maximize the “legibility” of essential information. Differentiate elements in ways that can be described (i.e., make it easy to give instructions or directions). Provide compatibility with a variety of techniques or devices used by people with sensory limitations.

Tolerance for Error

The design minimizes hazards and the adverse consequences of accidental or unintended actions. Arrange elements to minimize hazards and errors: most used elements, most accessible; hazardous elements eliminated, isolated, or shielded. Provide warnings of hazards and errors. Provide fail-safe features. Discourage unconscious action in tasks that require vigilance.

Low Physical Effort

The design can be used efficiently and comfortably and with a minimum of fatigue. Allow user to maintain a neutral body position. Use reasonable operating forces. Minimize repetitive actions. Minimize sustained physical effort.

Size and Space for Approach and Use

Appropriate size and space is provided for approach, reach, manipulation, and use regardless of the user’s body size, posture, or mobility. Provide a clear line of sight to important elements for any seated or standing user. Make reach to all components comfortable for any seated or standing user. Accommodate variations in hand and grip size. Provide adequate space for the use of assistive devices or personal assistance.

Multi-modal interaction

More than one mode of interaction is an important principle of universal design. Such design relies on multi-modal interaction. However, it should always be remembered that multi-modal interaction is not just about enhancing the richness of the interaction, but also about redundancy. Redundant systems provide the same information through a range of channels, so, for example, the information presented graphically is also captioned in readable text or speech, or a verbal narrative is provided with text captions. The aim is to provide at least an equivalent experience to all, regardless of their primary channel of interaction.

Sound in 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 [237]. 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. The dual presentation of information through sound and vision supports the 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 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 [237]. 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. The dual presentation of information through sound and vision supports the 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. 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.

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 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. There are problems associated with the use of handwriting as an input medium, however, and in this section, we shall consider these. We will first look at the mechanisms for capturing handwritten information, and then look at the problems of interpreting it

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. There are problems associated with the use of handwriting as an input medium, however, and in this section, we shall consider these. We will first look at the mechanisms for capturing handwritten information, and then look at the problems of interpreting it 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. But, like speech, the gesture is user-dependent, subject to variation, and co-articulation. The technology for capturing gestures is expensive, using either computer vision or a special data glove.

Designing Interfaces for diversity, considering three key areas: disability, age, and culture

Interfaces are usually designed to cater to the ‘average’ user but as people are diverse, there are many factors that must be taken into account when we are trying to get closer to a universal design.

It is estimated that at least 10% of the population of every country has a disability that will affect interaction with computers so the design of software and hardware should not unnecessarily restrict the job prospects of people with disabilities. Most common sensory, physical, and cognitive impairments and the solutions for the issues they raise for interface design are as follows.