Usab ility

Usability is a vital element to measure the quality of a product, which is a multidimensional construct that can be evaluated from many aspects, including whether the interface is functionally correct, efficient to use, easy to learn, easy to remember, and pleasing (Molich et al., 1999; Jeng, 2005). Usability is the most important principle, encompassing learnability, efficiency and effectiveness of a product (Albert 2013). Efficiency represents the accuracy and how quickly goals can be achieved in testing. Effectiveness represents the accuracy and completeness of specified goals achieved in particular environments. Satisfaction shows the degree of comfort and acceptability of the working system (Molich et al., 1999, Albert 2013; Lin, 2013). Usability testing is based on business goals and context, user needs and product content. Emotion and affect emphasizes the degree of happiness of using products (e.g. decision-making and subjective wellbeing). Relative measuring standards include subjective and positive attitudes of product use. The affect of an interface is based on antecedents (e.g. willingness-to-pay) and consequences (e.g. money spent on products). Experiments in usability involved checking the dynamics, the degree of complexity, and how the product is situated and temporally-bounded (Hassenzahl, 2006).

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In addition, usability does not exist in any absolute sense, but only can be defined in particular contexts. It means that there is no absolute measure for usability. If the usability of an artefact is defined by the context in which that artefact is used, measures of usability must of necessity be defined by that context too. Despite this, there is a need for broad general measures which can be used to compare usability across a range of contexts. The System Usability Scale (SUS) is a reliable, low- cost usability scale that can be used for global assessments of systems usability. SUS is a Likert scale. It is often assumed that a Likert scale is simply one based on forced choice questions, where a statement is made and the respondent then indicates the degree of agreement or disagreement with the statement on a 5 (or 7) point scale. However, the construction of a Likert scale is somewhat more subtle than this. The approach for calculating the corresponding scores for SUS to measure the usability is defined by previous study (Brooke, 1996; Borsci, 2009; Bangor et al., 2009; Kortum, 2013). Another popular way for usability testing is Software Usability Measurement Inventory (SUMI) which provides a valid and reliable method of measuring users' perception of the usability (an objective way of assessing user satisfaction with software). SUMI evaluation combines Affect (user’s emotional feeling of interacting with product), Helpfulness (user's opinions that the software communicates in a helpful way) and Control (users feels that he and not the product, setting the pace). However, SUMI has a significant drawback that the accuracy of the findings is limited (this can be solved by adding a small number of open question to the SUMI questionnaire) (Brooke, 1996; Arh, 2008)

2.6 Su mmary

There are still many illiterate people in the world, and these people are mainly distributed throughout South and West Asia, Sub-Saharan Africa, and the Arab States. Some developed countries also face problems of growing illiteracy (Speaking Books, 2013). Illiterate people cannot read text and may have a low level understanding of how to use electronic devices (Fingeret, 1983; Cooter, 2006; Benseman, 2011). In New Zealand, the majority of illiterate people are adults and they may have few opportunities to use computers (Benseman, 2011). Illiterate people have a high probability of having health problems. It can be difficult for illiterate people to be independent and enjoy an optimal quality of life without reading and writing skills (Nejati, 2008).

Text free interfaces are interfaces with minimal or no text that use other components like images and audio to assist illiterate users. Text is not the exclusive method of information representation. Audio in interfaces is the most widely used feature for delivering information to illiterate people. Currently, universal signs and text-free maps are two main methods to help illiterate people and non-local-

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language speakers to find the way around. Universal signs point to current or nearby landmarks, and the development of text-free map technology lags far behind that of text-maps and there is no specific text-free category within new technology to replace the text for illiterate people and non-local- language speakers (e.g. audio or symbol functions to replaces the text, positioning and navigation). Therefore, we need to evaluate which kind of text-free map is most suitable for illiterate people and non-local-language speakers.

The principles of text-free map design need to consider cognitive maps. Cognitive maps mainly indicate routes, paths and environmental relationships (Tolman, 1948; Montello, 2002). However, symbols used on cognitive maps to represent landmarks are not the generalized symbols that are broadly understood by the public. The scope of cognitive maps has boundedness, and cognitive maps are only able to show limited areas. Cognitive maps only show the environmental relationships for each position and those positions may not be precise. Therefore, cognitive maps leave many gaps in providing a template for wayfinding functionality that could be used to develop a text-free map for illiterate users.

Compared with traditional paper maps, online maps can provide many dynamic features for people to save time in travel planning and they enhance the efficiency of travelling to a high degree, but this functionality is not currently available to illiterate users. In this research, we investigate the range of functionality that may be required for text-free maps.

Usability is a vital element to measure the quality of product, which is multidimensional construct that can be evaluated from many aspects, functionally correct, efficient to use, easy to learn, easy to remember, and pleasing (Molich et al., 1999; Jeng, 2005). The corresponding principle includes learnability, efficiency and effectiveness of using the product will be the foundation for text-free map evaluation experiments design in this research.

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3. Research Procedure

This Section describes the methodology of this research. The approach consists of four parts: two surveys to define suitable symbols for the text free maps and features to be included in the design; the design of a set of web maps and a usability test (100 respondents) of the designed map evaluation. The green part in Figure 7 below shows the methodology, and the numbers refer to chapter numbers.