**8. Usability evaluation for visual impairment**

People with visual impairment have a unique requirement to be able to interact with smartphone assistive technology. Such a unique requirement can cause a gap between the ideas of the developers of smartphones and the needs of individuals with visual impairment, leading to either a lack of adoption or abonnement of smartphone. There is an obvious need of collaboration between vision rehabilitation professionals and expertise in computer sciences and involvement of visually challenged individuals, and their participation, in designing an innovative, acceptable, and adaptable mobile assistive technology that will assist to develop a user-centred technology.

Therefore, usability testing or evaluation while developing of accessible features and apps for smartphones is essential so that the features and apps are accepted and adopted by the end users. For examples, a smartphone may have many built-in multiple functions, but if it may not be usable to target population due to inaccessible or discomfort on use. A systemic evaluation on the usability testing should be a part of developing for accessible features and applications of smartphones.

The potential gap between the unique experiences and challenges faced by people with visual impairment and ideas of designers are crucially important. The designer needs to understand the user-centered and user-friendly perspective while efforts have put in to develop various apps as assistive technologies for visual impairment, that the developers create the apps that meet the user's expectation and needs. The product should be designed that a person with a visual loss can access all accessible features or functions that they want to execute. There is a need for evaluation and testing whether there are any usability problems in using the features and applications by end the users.

Usability is an elusive concept. To define it explicitly, we have to devise measurements that reflect the user's experience of a product and the level of success we establish for the product. As a working definition, usability is the ease with which people in a defined group can learn and use a product. The characteristics of and relationships among the *tasks,* the *users,* and the *product* determine the product's usability. S. Rosenbaum Dec. 1989

Designers or ergonomics engineers may face various challenges to perform usability evaluation for assistive products in an efficient way. Several factors may account for this, such as multiple influencing factors, so many non-specific tests and evaluation methods. There are methods available to do usability evaluation for assistive technology. Among them, Kwahk and Han has designed a simple usability evaluation framework of the electronic audio-visual products that can help the evaluators while conducting usability evaluation of their products in rational way (**Figure 9**). The framework is not specifically designed for smartphones apps and features, but the principles can be applied to other categories of assistive products with a minor change as per product designed. The framework provides a concise model how the evaluation should be done based on four parameters, i.e., first, user information; second, products information; third, user activity information; and fifth, the environment information [34].

The user information is important when the product is targeted at the users with special needs, for examples, individuals with visual disabilities or any other physical disability. The product information is required to understand the context of evaluation, for examples, form of the products- paper-based descriptions, mock-ups of the products or computer-based prototypes or finished products, etc.; level of the products in terms of perceived value: high-end, mid ranges, low end, etc. The environment and socio-cultural factors are also influence the user's operation and performance of the products.

Kwahk and Han further described five different techniques for evaluating usability of a product in human-electronic devices or computer- interface areas. The evaluator can select the suitable technique as per the context of the product and feasibility for conducting. They are as follows:

1.Observation/inquiry techniques

#### **Figure 9.**

*Usability Evaluation Framework for electronic audio-visual products. (Source: Kwahk and Han [34]).*

*Smartphones for Vision Rehabilitation: Accessible Features and Apps, Opportunity… DOI: http://dx.doi.org/10.5772/intechopen.97703*


The detail of each evaluation technique is beyond the scope of this book, but a brief description is given here. The empirical or usability testing with real users helps the designers to understand the experiences and challenges faced by people with disabilities while using assistive technology. Therefore, a designer can stress on empirical testing of the products [35]. Think-Aloud protocols are a dominant method in usability testing. There are two Think-Aloud techniques for usability testing that use commonly by the usability specialist; A Concurrent Think Aloud (CTA), in which experts request the participant to verbalise their thoughts as they perform the tasks with the help of the devices. Experts also use Retrospective Think Aloud (RTA), where participants are asked to retrace their steps after they complete the tasks and share the challenges [36, 37]. There are the pros and cons of both protocols, so expert has to decide which technique is suitable for usability testing.

Usability testing is the practice of testing how easy a design is to use with a group of representative users or persons with disabilities. It usually involves observing users as they attempt to complete tasks and can be done for different types of product designs. It is often conducted repeatedly, from early development until a product's release.

The goal of both usability evaluation and usability testing is the same: to improve the usability of products or assistive technology.

The introspection technique is an effective method to rule out the basic causes of usability problems based on user's thought and feeling. Often, evaluators might have difficulty to identify the cause of usability problems. This is because the evaluators have not imagined these problems that people with disabilities would have encountered while using the assistive products. Identifying the causes of usability problems helps the evaluators to differentiate whether the problems are due to individual's disability or by imperfect interface design for the assistive products [38]. For example, a study conducted by H K Kim et al. on identifying interaction experiences of visually impaired people when they use with smartphones, the common usability problems encountered are shown in **Table 3**. The study indicates that the problems vary according to the severities of visual impairment.


#### **Usability problems**


*Source: Kim et al. [38].*

#### **Table 3.**

*Usability problems identified in the study among visually impaired people.*

### **9. Conclusion**

Individuals with visual impairment and blindness face various challenges and barriers in their everyday lives. These people need assistive technology to overcome these challenges and perform a wide range of daily activities, including reading and writing. These technologies vary from low technology to high end and specialized technology, including software programs. In the recent times, mobile technology has gained a lot of attention across the world and are incorporated many advance computer and information technologies features.

Smartphones, the most sophisticated mobile technology, have been developed as smart assistive technology for people with visual impairment in the few years with many accessible built-in features and accessible applications with the help of sound, haptic and gestures interaction, instead of vision-smartphones interaction. Such innovative accessible, user-centred and friendly technology has provided a new platform and opportunities for people living with visual impairment to overcome the very challenges and barriers encountered in their everyday lives. Many

*Smartphones for Vision Rehabilitation: Accessible Features and Apps, Opportunity… DOI: http://dx.doi.org/10.5772/intechopen.97703*

accessible apps have been shown to be of great value and support in performing a wide range of daily living activities in people living with visual impairment. Such technologies are less likely attached with a stigma compared to traditional assistive devices. Further, use of smartphones have certain advantages, such as easily portable, less discomfort on use, relatively low cost compared to some of traditional devices. With widespread availability of mobile technologies along with eyes-free human smartphones features and applications, there might be a corresponding need of developing a clinical guideline on the use of accessible features and applications.
