Abstract
The history of usability began almost 20 years ago when computers were about to be used outside the designer and programmer environment. Until the 1980s software was mostly produced and used by designers so usability was taken for granted. In 1983, the first computers providing a graphic interface and a mouse were produced by Apple for distribution on a large scale. The gradual introduction of computers to offices and houses began creating usability problems. The development of computers was guided mainly by the technology available at that time. Gradually, the impact of training costs, errors in the interaction between user and computer, and the evolution of studies regarding the “human factor”, carried out by psychologists and ergonomics experts, led to a reflection on the importance of the target users.
TopIntroduction
The history of usability began almost 20 years ago when computers were about to be used outside the designer and programmer environment. Until the 1980s software was mostly produced and used by designers so usability was taken for granted.
In 1983, the first computers providing a graphic interface and a mouse were produced by Apple for distribution on a large scale. The gradual introduction of computers to offices and houses began creating usability problems. The development of computers was guided mainly by the technology available at that time. Gradually, the impact of training costs, errors in the interaction between user and computer, and the evolution of studies regarding the “human factor”, carried out by psychologists and ergonomics experts, led to a reflection on the importance of the target users.
In order to facilitate usability, the first guidelines regarding the human factor were introduced (the first guidelines regarding the graphic interfaces were written by Apple in 1978). The first user models were developed on the basis of research in the field of cognitive psychology which emphasized the human limits in elaborating detailed information and establishing the minimum requirements that a software needs to possess. In the first usability laboratories, usability, and ergonomics experts worked to develop guidelines and user models as well as to evaluate product usability. In that period cognitive ergonomics developed as a result of the application of cognitive psychology theory to both interface planning and the dialogue between user and computer. However, these developments were not enough to establish usability. In addition, likely usability defects detected during the final phase of evaluation could be rarely corrected because of cost and time problems. The first attempts to change this situation were done thanks to the integration of the waterfall model to the traditional usability activities. The analysis of requirements phase was intermingled with new methods aimed at improving the identification of the user’s needs in terms of functionality and usability. Rapid-prototyping was introduced in the project phase and usability tests were often administered.
In the second half of the 1980s, in Scandinavia, the so-called participatory design encouraged the user’s participation in the design process, not simply as an individual but also as a member of a certain culture and organization. On the other hand, the user-centered model or human-centered design that began to be adopted at the end of the 1980’s, was characterized by three aspects (Norman & Draper, 1986):
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Direct involvement of the target user: In all the development phases from the analysis of the requirements to the final evaluation, the target user is as responsible for the product as the designer is
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Interactivity of the process: This process is articulated in cycles characterized by prototyping, evaluation and prototype changes, and achievement of the final product
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Multidisciplinary team that designs a product: Different people (designers, usability experts, software developers, graphic designers, technical writers, etc.) are all concerned with the outcome of a product
TopSome Definitions Of Usability
ISO/IEC 9126 standard (Information technology—Software product evaluation—Quality characteristics and guidelines for their use) defines usability as “the capability of the software product to be understood, learned, used and attractive to the user, when used under specified conditions”. On the other hand, ISO 9241-11 standard (Ergonomic requirements for office work with visual display terminals—Guidance on usability) defines it as “the extent to which a product can be used by specified users to achieve specified goals with effectiveness, efficiency and satisfaction in a specified context of use.”
Key Terms in this Chapter
Satisfaction: Utility of an entire system as perceived by users and the comfort level felt by them in using a product. It is a subjective aspect of usability. It is difficult to measure and can be impacted by both effectiveness and efficiency level. In many cases it can be considered the most important measurement of usability. Satisfaction can easily be measured by asking questions of target users through a questionnaire or an interview or by making notes of the comments made by target users while they are using the system. A qualitative analysis of user satisfaction is also a good indicator. However, it can be most useful if their attitude towards a product can be quantified.
User-Centered Design: Process that implies the involvement of the target user during the planning and developing cycle. It is composed of several activities and it is based on the interaction of various instruments for analyzing, observing, planning, and assessing.
Learnability: Degree of effort employed to achieve a level of competence in completing a task. A system is considered easy to learn if competencies required to use it are acquired after only a few repetitions of the task. The term “learnability” is widely used in the usability field sometimes as a synonym of “usability”. It is fundamental to make the distinction between the usability of a product as it is being used for the first time and usability when referring to more or less expert users.
Intuitivity: Degree of the effort rate required by a user in using a product for the first time. The less time and effort used, the more intuitive the product. This factor is very important in those products which involve occasional target users. It loses importance in those products which imply long learning sessions. An intuitive design makes comprehension of an object easy and improves information storage and recovery from memory.
User Experience: Experience gained by a target user while interacting with an interface that provides access to a website or another technological product. The user triggers a series of cognitive processes that let the user understand the investigated reality. It is obvious that more the user has a positive experience, the more the user will wish to experience it again. The main factors that determine the quality of the user experience are: waiting time, orientation while surfing and surfing comprehension.
Ergonomics: Discipline that deals with the plan and the design of facilities and environments for human use. In the computer science field, it concerns the planning of keyboards, mice, screens, and of the workstation (chairs, tables, lamps, etc.).
Efficiency: Relationship between the effectiveness level and the use of resources. It can be measured either by the number of errors made by the user before completing a task or by the time used to reach the goal. Efficiency can also be defined as the rate of effort used to successfully complete a task.
Effectiveness: Degree of achievement of a goal. Its measurement makes a connection between the fixed goals and the precision of the achieved goals. The simplest effectiveness index addresses the achievement of a goal: a product is effective when it allows the accomplishment of a task. If the goal is not achieved, effectiveness can be measured in terms of the number of operations necessary to accomplish the task. Another way to measure effectiveness involves the quality of the achieved results.
Human-Computer Interaction: Discipline that deals with planning, evaluating and implementing interactive systems by human beings. Moreover, it deals with the study of the most important phenomena related to it.