Optimising web site designs for people with learning disabilities

Much relevant internet-mediated information is inaccessible to people with learning disabilities because of difficulties in navigating the web. This paper reports on the methods undertaken to determine how information can be optimally presented for this cohort. Qualitative work is outlined where attributes relating to site layout affecting usability were elicited. A study comparing web sites of different design layouts exhibiting these attributes is discussed, with the emphasis on methodology. Eight interfaces were compared using various combinations of menu position (vertical or horizontal), text size and the absence or presence of images to determine which attributes of a site have the greatest performance impact. Study participants were also asked for their preferences, via a 'smiley-face' rating scale and simple interviews. 'Acquiescence bias' was minimised by avoiding polar ('yes/no') interrogatives, achieved by asking participants to compare layouts (such as horizontal versus vertical menu), with reasons coaxed from those able to articulate them. Preferred designs were for large text and images. This was the reverse of those facilitating fastest retrieval times, a discrepancy due to preferences being judged on aesthetic considerations. Design recommendations that reconcile preference and performance findings are offered. These include using a horizontal menu, juxtaposing images and text, and reducing text from sentences to phrases, thus facilitating preferred large text without increasing task times.