This chapter will discuss the previous and current studies in Human Computer Interaction (HCI). It elaborates HCI studies that related to usability evaluation models in general, and specifically for mobile applications. Additionally, it details the studies related to usability problems of mobile applications for visually impaired users. Finally, proposing conceptual usability evaluation model for mobile application for visually impaired.
Human Computer Interaction (HCI) has known as multi Specializations area (e.g., engineering, design and psychology) that comprises the theory, design, implementation and evaluation of the relation in using and interaction between humans and computer devices. The interaction in HCI refers to interaction and interface (Kim, 2015).
Activity theory mentioned that the computer is tool, which in the middle between humans interaction and their environment, thus reconstruct the overall activity of computer use the best way to find enough understanding of human computer interaction, also activity theory pointed that, there are some questions emerge when computer use, some of these questions are: ‘Does computer use correspond to the level of particular activities, to the level of actions, or to the level of operations?’, ‘What are the objectives of computer use by the user and how are they related to the objectives of other people and the group/organization as a whole?’ (Kaptelinin, 1996).
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Usability and Human Computer Interaction have been central and main part to develop systems. HCI and usability improve and support the system services, also giving users their requirements and necessities. HCI helps analysts and designers to identify software factors to be successful, while usability helps to prove that the software has efficiency, effectiveness, safety, utility, learnability, memorability and usability to evaluate in really using, then finding the users’ satisfaction. HCI with usability help users to be satisfied and achieve their goals and tasks (Katy, 2016) (Issa, T., & Isaias, 2015).
In the beginning, without clear definition of usability, Human Computer Interaction HCI is varied and dispersed field, especially in the issues that related to user interface and end user application. Therefore, with development of cognitive science there have started discussions of how to apply psychological research to human interaction with computers (Waddell, Zhang, & Sundar, 2016).
Moreover, HCI has grown as important area increasingly, as the result of growing computers and embedded devices, also the height of their impact in almost all sides in our lives, so these devises are not just functionalities computational devices, so HCI has focused on how to design interaction and implement interfaces to give high level of usability, which including easy to use of interface, task efficient, safety, and correct task completion. Therefore, usable and efficient interaction with the computing device lead to higher productivity (Kim, 2015).
Usability evaluation is a combination of methodologies which are used to conduct the measuring and evaluating the usability attributes of a system, this procedure to find clearly usability problems in design of system (A. M. Saleh & Ismail, 2015; Shawgi, E., & Noureldien, 2015). During the last twentieth years, Human Computer Interaction (HCI) researchers and usability experts have intensely addressed usability evaluation, through proposing and providing a considerable number of usability evaluation methods and models, which were used to measure usability as a quality construct (de Oliveira, K. M., Lepreux, S., Kolski, C., & Seffah, 2014).
To explain the current situation of usability, will be reviewed existing usability evaluation: standards, models, guidelines, theories and studies, which related to software, websites, mobile application and mobile application for visually impaired.
In recent years there is increased and variety of software, thus appeared a new issue, related to design successful software that actually achieve their purposes with ease of use, this task is not easy. Therefore, today there are several different standards, models and guidelines to evaluate the usability of software (e.g., ISO 9241, Nielsen Model, GQM approach). Some of these models, guidelines and standards are base, to develop usability evaluation models for mobile application in general, and for mobile applications for users with specific needs, while these models difficult to use direct without modify for mobile application for specific needs users.
Nielsen defined usability as a quality attribute which evaluates how easy using interfaces. Added more the term usability refers to methods used to improve ease of use during the design process. Usability is defined by five usability attributes as is illustrated in table 2.1(Nielsen, 2012).
- Attribute
Usability Measures
- Learnability
How user can easily learn the system work to fast start doing some task by this system.
- Efficiency
User finds the best productive by the system after learning it.
- Memorability
User can easily remember using of the system after some period of leaving without new learning of everything.
- Errors
User faces fewer errors during using the system, and can easily recover from them if there are errors, also the system without catastrophic errors
- Satisfaction
User enjoys and satisfies during using the system.
Nielsen attributes have been used in numerous usability studies and models. Efficiency and satisfaction attributes were used in some models and standareds, such as MUSiC model (Bevan, 1995), ISO 9241-11 (ISO, 1998) and integrated model (Dubey, Gulati, & Rana, 2012). While efficiency, learnability and satisfaction were used in some others such as QUIM (Seffah et al., 2006) and Abran et al. (2003).
Additionally, there are numerous usability evaluation models for mobile applications used Nielen’s attributes. Saleh et al. (2017) used all Nielen’s attributes. Efficiency, learnability and satisfaction used in some others, such as PACMAD model, Baharuddon et al. (2013) and Tan et al. (2013). While mGQM used efficiency and satisfaction (Hussain, 2012).
However, efficiency and satisfaction are important usability attributes that used in almost of all usability models, as result of their importance in usability evaluating, as well as errors, memorability and learnability are an important usability attributes, which have been less using in the other following models.
Metrics for Usability Standards in Computing (MUSiC) was developed based on ISO 9241 standard. The developer pointed that, measuring effectiveness, efficiency and satisfaction are important to achieve usability evaluation with a better level for a specific goal, also offered some usability metrics such as productive period, temporal efficiency and task effectiveness as a part of user performance measuring. Therefore, this model required support to evaluate user satisfaction, thus questionnaire of 50 items to evaluate user satisfaction was offered as solution of this gap. Software Usability Measurement Inventory (SUMI) was developed as a part of the MUSiC (Bevan, 1995). SUMI evaluates 5 usability measurements including effectiveness, efficiency, control, learnability and helpfulness. However, MUSiC model cannot cover other sides of usability, such as learnability or user satisfaction (Seffah et al., 2006).
Furthermore, depending on the attributes that related to user and lost in this model, so it cannot give clear and completed result in usability evaluation (A. Saleh, Bintiisamil, & Fabil, 2015). Additionally, MUSiC and SUMI both are not enough to evaluate mobile application for disable users, due to the fact that both are general models.
