CHAPTER 2 Literature Review
2.4 Designing for Dynamic Diversity
Some persons with disabilities have limited access to the benefits of the information society because their special requirements for proper assistive devices are seldom taken into account in user interface design. Mainstream design has focused on accommodating the needs of the able bodied users only. The needs of persons with disabilities are rarely considered by traditional system design (Bergman & Johnson, 1995). The concept of mainstream design was produced for all the people to accommodate one design, regardless of individual differences and the needs of users with disabilities. In order to provide a better solution, accommodated approach was later created, but the flexibility was limited. While universal design is extending the
usability of systems to encompass a greater variety of users. Universal design is the process of creating devices, environments and systems which are usable for people with the widest possible range of abilities (Dorsa, 2002). The philosophy of universal design provides everybody with an opportunity to participate in life and the activities taken place in our society on equal terms. For this perspective, the designer and researchers are supposed to take the need of all potential user groups, including minority groups such as persons with disabilities into consideration.
The principles of universal design are advocated in various fields recently. The term of “universal design” appeared first in the literature of architectural design in 1991 (Mace, Hardie, & Place, 1991). The architects rarely addressed the mobility and the communication needs of persons with disabilities in the beginning. The concept of universal design developed for the user with a disability is becoming more accepted (Wallace, Flippo, Barcus, & Behrmann, 1995). Universal design is the application of an architectural concept in which the designers of architectural spaces planned and created their products with all persons in mind, rather than adapting to personal needs and strengths after the fact. The idea behind universal design applied in architecture is to create structures to accommodate the widest spectrum of users, including those with disabilities. It considers the possible users’ needs in the design process and its mainstream systems are embedded with flexible options for accommodation. It
reduces the need of extra aids for the disabled. The system should be designed to be used by all people and to the greatest extent as possible. The seven principles of universal design have widely been used as a usability standard (Nielsen, 1993) shown below:
1. Equitable Use. Equitable use means the design is useful and marketable to any
group of users. Furthermore, it promotes equal services to all users with no discrimination, and the design is generally considered appealing.
2. Flexibility in Use. Flexibility in use ensures that the design accommodates a
wide range of individual preferences and abilities. Choice in method for using the service and adaptability to the user’s pace are central concepts in flexibility.
3. Simple and Intuitive Use. Simple and intuitive use explains that the use of the
design or service is easy to understand, regardless of the user's experience, knowledge, language skills, or current concentration level.
4. Perceptible Information. Perceptible Information means the design
communicates effectively the necessary information to the user. Using different modes of information delivery, highlighting essential information, giving clear and easy instructions, and providing information in an accessible way that can be absorbed by people with sensory limitations and in a way that
improves quality of perceptible information.
5. Tolerance for Error: Tolerance for error means the design minimizes hazards
and the adverse consequences of accidental or unintentional actions. This concept provides more functions to universal accessibility of products.
However, in service delivery, this concept would discourage actions that may have adverse consequences.
6. Low Physical Effort. Low physical effort means the design can be used
efficiently and comfortably for the individual; repetitive actions and sustained physical effort are minimized for the user.
7. Size and Space for Approach and Use. To meet the needs of all users, proper
size and space are provided for approach and the use of the service or product, regardless of body size, posture, or mobility.
In the early 1980s, the idea of universal design was coined accessible design (Bauer & Kroeger, 2004). Several comprehensive universal design approaches,
“design for all”,“accessible design”, and“inclusive design,” have joined forces in the effort to meet the needs of the disabled people than ever before (Stary 1997, Keates et al. 2000). Universal design must be based on barrier-free design to provide more suitable living environments for most users. The seven principles have broad implications in the field of asset development program delivery. Assisting individuals
living in poverty to acquire assets, program and premise universal accessibility give each participant an equal chance of success. Universal design inserts the additional design that integrates most users’ needs into design process at the first step. When assistive technologies draw more attention, more flexible solutions should be designed and easily accessed by the users. The development in human-computer interface should take into account the diversity of the potential user population (Newell & Gregor, 1999).
A good system design allows users to retain a high level of independence and control in their lives. The idea of universal design concerns the needs of persons with disabilities. However, current system based on universal design typically produces a tool which is static and very limited in its ability to adapt to the shifting needs of users as their abilities change. Designing for dynamic diversity aims to develop systems that are appropriate for users whose abilities are different and subject to changes both in the users' development over their lifespan. People with severe motor disabilities need extra aids due to their specific limitations. System design or products need to address the wide variations in the nature and severity of disabilities between individuals. In advance, it is necessary to contemplate the fact that the user is a dynamic entity. A user’s life more or less includes a decline over time in physical and sensory functions. Most of the current products created with universal design are
more of a result of modifying mainstream products to be accessible by as broad a range of users as possible. Such products usually fail to accommodate a large variety of physical disabilities and provide less flexibility. Thus, to counter the design inadequacy mentioned above, it is important to be aware of not only the diverse characteristics of people with disabilities, but also the dynamic aspects of their abilities.
Figure 2-17 The relationship of three design philosophy
When designing assistive system for people with disabilities, it is important to focus on the characteristic of the client, and to be aware of the range of diversity.
A versatile design may shorten this process by providing alternative devices for the same already-known technique.
As shown in Figure 2-17, the traditional design has exhibited large limitations in the diversity dimension and the dynamic dimension. For universal design, it takes the diversity into considerations and extends the dynamic dimension. However, the current system or product of universal design is not enough to adapt to the change of a user’s needs in their lifetime. The system design following the approach of designing for dynamic diversity must reflect the dynamic condition of people with disabilities.
Some users increase their needs due to aging and degeneration, while others gain better control as their condition improve by rehabilitation. Related changes to the system should be made accordingly as the functionality of the individual user changes.
For education, teachers often use scaffolding strategies to support students in learning new skills. The scaffolding strategies are widely applied to enhance students’
learning (Greenfield, 1984; Li & Chen, 2005; Pea, 2004). In the research of educational technologies, there are many representations to enhance learner success in achieving the complex task, such as fading interfaces, multiple media and intelligent
agents. Designing for dynamic diversity needs to support the scaffolding strategies to determine the appropriate solution for the users.
As shown in Figure 2-18, a user is defined by a point in the multi-dimensional space which specified their functionality, and the relationship of the functionality to the environment in which the user operated. The position of the user’s functionality changes substantially throughout the user’s life due to aging and motor abilities change in lifelong perspective. Indeed, it is impossible to design a product that is truly accessible for all potential users in any time. However, based on the concept of designing for dynamic diversity, the ideal assistive system should extend the flexibilities of the system to meet the needs of individuals. Furthermore, it is necessary to support additional options in accordance with individual’s dynamic changes. The designer must consider many factors reflecting the diversity types, disability degree, and their interplay.
For example, the standard keyboard is the traditional text entry device which provides only one size and one kind of layout. The novice user spends much time practicing fitting into the QWERTY layout. In addition, the standard keyboard is designed only for able bodies and cannot be accessed easily by people with motor disabilities. Therefore, the on-screen keyboards provide more flexible design in the system. Some on-screen keyboards allow users to resize the layout. But novice user would encounter difficulty in determining an appropriate one. Therefore, for the approach of designing for dynamic diversity, embedding some detection tool or
Figure 2-18 The multi-dimension of three design philosophy
access solution.
In terms of software system, the approach of traditional design supports limited options for users. Based on the idea of universal design offers more options but lacks of a suggestion to meet the users’ needs. Therefore, the philosophy of designing for dynamic diversity could dynamically adjust accordingly to the users’ performance.
For example, the accessibility features are very limited in the early operating systems.
And then, the modern operating systems grant more accessibility features for persons with disabilities. However, it is very difficult for disabled people to adjust the appropriate options by themselves. As the range of available configuration facilities increases, more support for configuration will become necessary. The best way to aid persons with disabilities to find the appropriate options is to embed the detection tools to help them configure the setting. Here is another example of the on-screen keyboard design for persons with visual disabilities. As users grow older, their visual capabilities degrade. The on-screen keyboards should provide a proactive way of increasing the font size or enlarging the layout automatically and gradually. In order to support appropriate configuration, some mechanism for recognizing a user’s text entry performance is therefore desirable.
Mainstream system design could only of use to able-bodied users. The designing of some assistive system respond to the need of diversity for some potential user
population, however, the idea of designing for dynamic diversity is not being emphasized.
CHAPTER 3
D 3 On-screen Keyboard Design
3.1 System Architecture
In order to design a bilingual on-screen keyboard for Chinese users, D3 on-screen keyboard was developed in both English and Chinese keyboarding methods. Figure 3-1 displays the architecture of D3 on-screen keyboard. D3 on-screen keyboard comprises three major modules that include selection methods, layout designs and enhancement control. In addition to the three common selection methods which current on-screen keyboard support, D3 on-screen keyboard also provides the coded selection method. The layout of D3 keyboard embeds three types of arrangement:
namely QWERTY, alphabetical, and frequency of use. Additionally, the configurations allow users to set up the high contract layout and resize the layout to fit their specific needs and the transparency layout can improve flexibility for word processing with a large on-screen keyboard. Furthermore, D3 keyboard provides some additional features to enhance the performance of the text entry for novice users, include voice feedback, an Internet macro, a scaffolding strategy and a layout
adaptation evaluation program.
Macros can reduce text entry for commonly used text and keyboard commands.
The Internet macro layout allows users to type a uniform resource location (URL) with only a few keys, and its function keys instead of having to travel to the menu bar of the browser. The visual prompt layout provides visual cues of associated codes on the coded selection method, and can accelerate the learning curve of novice users. The layout adaptation evaluation program helps the user to choose an appropriate layout size based on the results of only a few trials. In order to satisfy the needs of various Figure 3-1 System architecture of D3 on-screen keyboard
be controlled by a wide variety of assistive devices, include a touch-screen, mouse, head pointer, keyboard, joystick or switch.
3.2 Selection Methods
Direct selection, scanning, and encoding techniques are three major approaches used by people with motor disabilities to operate computers (Harris & Vanderheiden, 1980). These three alternative access techniques require different cognitive and motor skills, and produce different results in terms of accuracy, text entry speed and degrees of fatigue (Beukelman & Mirenda, 2005; Glennen & DeCoste, 1997). With direct selection the individual could use the point devices to choose any of the items in the selection set randomly. Scanning and encoding techniques are indirect selections.
With indirect selection, there are intermediary steps involved in making a character.
Most on-screen keyboards support point-and-click, dwell and scanning selection methods. Point-and-click selection method is suitable for people with limited movement range who cannot travel across the standard keyboard, but are able to operate a pointing device such as a trackball or touch pad. If the user is unable to press a button or switch but is able to keep the pointing device steady for a short time, dwell selection is an alternative solution. For users only can physically control one or a small number of muscle movements, scanning selection methods are the viable
control option. The current on-screen keyboards rarely integrate the coded selection method.
Based on the concept of designing for dynamic diversity, D3 on-screen keyboard integrated supports point-and-click, dwell and scanning selection methods.
Besides, the text entry system integrates the coded selection method and high performance scanning selection method.
3.2.1 Coded selection Method
An encoding technique is a good alternative solution for persons with motor disabilities to increase their speed of text entry. The chorded keyboard is a type of encoding techniques. Previous studies have found that chorded keyboards are effective for people who have limited arm range but have retained precise finger control (Richardson et al., 1987; August and Weiss, 1992). The encoding techniques of text entry systems afford one-handed typing which is considered a benefit to disabled users (Kirschenbaum, Friedman, & Melnik, 1986). Some physical keyboards use coded selection methods. However, the current on-screen keyboards rarely integrate the coded selection method.
The coded selection methods use a combination of a few keys to create keystrokes for each letter. The coded selection method of D3 on-screen keyboard is based on numeric and the user can generate a character by pressing two numeric keys
which enable users to manipulate numeric keypads or switches to activate a number code. As the alphabetic layout shown in Figure 3-2, the first key specifies a group and the second key selects a character in that group. For instance, the letter 'a' is generated when the number '4' and '7' are pressed in order. The '0' is used as a cancel button when a typing error occurs.
Figure 3-2 The numeric coded selection design
The efficiency of text entry is dependent on the number of motor movements and steps required. Thus, based on Fitts' law of movement efficiency (Fitts, 1954), the punctuation and commands of D3 on-screen keyboard are arranged in order of their frequency of use to minimize the traveling distance between fingers. The primary cost of the coded selection method is the extensive learning required associating the finger combinations with their corresponding actions. Therefore, after extensive practice, the coded selection methods have been found to support a more rapid word transcription
processing than the QWERTY keyboard, possibly due to reduced movement-time requirements (Richardson, Telson, Koch, & Chrysler, 1987).
3.2.2 Scanning Selection Method
Persons with severe motor disabilities who cannot use direct selection typically resorted to scanning selection method as a means of accessing assistive technology.
Scanning selection methods requires several more steps than direct selection. The row-column is common option for most of the on-screen keyboards. However, the process of row-column scanning is very time-consuming and it is difficult to enhance text entry speed (McDonald et al., 1982). The advantage of scanning is that it requires very little motor control to make a selection; however, passive waiting and required visual tracking are two factors that make row-column scanning inefficient (Cook &
Polgar, 2008). Group-row-column scanning is typically more efficient than row-column scanning.
Figure 3-3 The sequence of group scanning
D3 on-screen keyboard employs the group-row-column scanning method. The layout is divided into nine blocks, as shown in Figure 3-3. The user activates the switch when the highlight arrives at the target group. The highlight then scans each
row in the group until the user activates the switch again. Finally, the highlight scans across each item in the selected row until the user activates the switch.
In addition to the scanning technique, the access time for a character selection is considered. The arrangement of the characters in the layout is crucial for scanning since it defines the access time of each character and the characters are arranged according to frequency of use, as shown in Figure 3-4 and Figure 3-5. The principle guiding the design is that different letters occur at different rates in the text. For example, based on the results of frequency analysis, the frequency of the letter "e"
among all characters is 13%, and that of the letter "z" is only about 0.2% (Nesbat, 2003). Furthermore, the space key is prominent in text entry task and is located on the highest priority.
Figure 3-4 Waiting periods of each cell Figure 3-5 The frequency-of-use layout
3.2.3 Point-and-click Selection Method
Pervious research (Levine et al., 1986; Szeto, Allen & Littrell, 1993 ) has compared the performances of using direct selection, scanning and encoding technique, and direct selection is the fast in terms of typing rate. Point-and-click is a type of direct selection. For persons with good range of movement and fine motor skills, Point-and-click selection method is an efficient way to access the computer.
However, it requires a consistent range of movement and more motor control.
The current point-and-click interactions require the use of the shift key to type capital letters and punctuation marks. Besides the conventional Point-and-click selection method of commercial on-screen keyboard support, D3 keyboard could use the double click rather than the shift key and the conjunction key simultaneously.
Figure 3-6 shows the designed layout. A single-click is applied to generate a lowercase letter or a number while a double click generates a capital, function key or punctuation mark.
Figure 3-6 The double click layout with alphabetic layout
3.3 Designs of Layouts 3.3.1 Layouts Arrangement
The characters arrangement of the layout is a crucial variable in determining the speed, the accuracy, and the efficiency of the interaction between users and the computers. There are many ways to arrange and group the items in a layout.
The characters arrangement of the layout is a crucial variable in determining the speed, the accuracy, and the efficiency of the interaction between users and the computers. There are many ways to arrange and group the items in a layout.