Comparing the efficacy of different web page interface attributes in facilitating information retrieval for people with mild learning disabilities

• Main Author: Williams, P. E.
• Other Authors: Duke-Williams, O.
• Published: University College London (University of London) 2013
• Subjects: 020
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.626005

This research aimed to determine what web page attributes facilitate optimal website design for use by learning-disabled people – a topic hitherto rarely addressed. Qualitative research developed methods appropriate for this cohort, determined attributes that impact on usability and explored ways of eliciting preferences. Attributes related to menu position, text size and images, which were then examined quantitatively by comparing web pages of different layouts. Task-times were analysed, determining which attributes have the greatest impact on performance. The main predictor of task-time was menu position, followed by text size. Images did not affect performance. The study also found that learning-disabled people have only ‘serial access’ to information when searching individual pages – it being imbibed sequentially until the required content is reached. Words on the left of horizontal menus were found quicker than those in the middle or right. Information access took longer from vertical menus, possibly because of the juxtaposition of distracting body text. Images were ignored until reached ‘serially’– and thus did not help signpost content. Small-text was consumed quicker than large, as the latter took up more lines and required more eye movements to negotiate. A three category rating scale and simple interviews elicited web design preferences. The ‘neutral’ category proved troublesome and so a refined four category scale without this mid-point was adopted which yielded a greater variety of results. In verbally eliciting preferences, ‘acquiescence bias’ was minimised by avoiding polar interrogatives - partly achieved by comparing different designs. Preferred designs were for large-text and images – the reverse of those facilitating fastest retrieval times, a discrepancy due to preferences being judged on aesthetic considerations. Design recommendations are offered which reconcile preference and performance findings. These include using a horizontal menu, juxtaposing images and text, and reducing text from sentences to phrases – facilitating preferred large-text without increasing task-times.