Usability Research References

Human Factors International (a well-known consulting firm) does end-of-year summaries of important usability research findings in bite-size bullet pieces. The items are useful for designers and researchers working on any UI topic, but there's a definite focus on web design (for obvious reasons). The review is titled Yeah but can you give me a reference?

The 2005 list includes:

• What users think/ say they will do in focus groups and what they actually do in usability tests often differs. (Eysenbach and Kohler, 2002) [This is a truism often repeated, but now there's a reference you can cite!]
• Tolerable wait time is about 2 seconds. Users will wait somewhat longer if there is feedback that something is happening. (Nah, 2004)
• Use of whitespace between paragraphs and in the left and right margins increased comprehension by almost 20%. (Lin, 2004)

They did the same in 2004 and 2003. Interesting cites from those years include:

• Less than half of users take advantage of breadcrumbs (even when most report having noticed them). (Lida, Hull and Pilcher, 2002)
• Under click-stream analysis, breadcrumbs are not more efficient than other approaches to navigation. (Lida, Hull and Pilcher, 2002)
• Color similarity has a stronger perceptual influence than common region, proximity, or grouping. (Beck and Palmer, 2002)
• Photographs do not increase the trustworthiness of already credible sites. They do, however, improve the credibility of sites that are not generally perceived as trustworthy. (Riegelsberger , Sasse & McCarthy, 2003)
• Heuristic review tends to uncover usability issues related to presentation (skills- and rules-based user performance). (Fu, Salvendy and Turley, 2002)
• Usability testing tends to uncover issues related to domain-specific knowledge and interaction (knowledge-based user performance). (Fu, Salvendy and Turley, 2002)

On the final subject, another issue of the HFI newsletter features an article on Pitting Usability Testing Against Expert Evaluation. This is an excellent piece, summarizing well the things that expert evaluation can do for you and what to realistically expect from usability testing -- including where they overlap.