Collaborative Environments: Accessibility and Usability for Users with Special Needs - Community-Built Databases: Research and Development - page 333

Fig. 13.5 Evaluation of final users
the computer. Those users affected by vision impairment obtained different results
in the use of VisualPedia. Low vision users did not encounter any problem, while
blind users experienced troubles using the screen reader, because of the presence of
extra information within VisualPedia pages.
The results obtained by the experiment performance suggest that VisualPedia is
generally easy to use and potentially useful for educational purposes. Figure 13.5
illustrates for each of the three tasks the users were asked to perform, the number of
people who found it easy, needed training, or found it difficult to use.
The comparison between the results obtained by the two usability evaluation
phases highlights a contradiction: even if VisualPedia resulted generally easy to be
used by users with disabilities, the experts found severe usability issues. Thus, the
experiment with final users pointed out that a useful system such as VisualPedia can
provide a high acceptability by its users despite the presence of usability problems.
The VisualPedia case is an example that highlights how often, in analyzing
collaborative systems, the results obtained by applying cognitive engineering
methods of usability evaluations are very different from those obtained by experi-
ments with the final users. Therefore, in the next section, we propose a model for the
evaluation of collaborative systems that considers not only the aspects taken into
account by cognitive engineering, but also some other aspects related to accessibility,
usefulness, and acceptability of the system by its final users.
13.5 A Model for Collaborative Environments
In this section, we focus on the usability factors that should be considered when
designing and developing collaborative e-learning environments such as VisualPedia.
The experience gained during the usability analysis of VisualPedia has shown
how an unusable system, according to a heuristic evaluation performed by