Usability Updates Newsletters

November 2005

Age-Related Research-Based Usability Guidelines

by Dr. Bob Bailey

Introduction

People are living longer in the western world. At least 70% will live past age 65, and about 40% past age 80. Unfortunately, there are definite, predictable degenerative effects of aging on a person’s ability to effectively and efficiency interact with Web-based systems.

One effect of aging is diminished vision – loss in near vision, reduced field of view and contrast sensitivity, and reduced color sensitivity in the blue-green range. Psychomotor impairments include increased response time, and poorer tracking with a mouse. Also, older users experience reduced attention, and reduced memory capability, including working memory, episodic memory and procedural memory. Studies show that many Web sites clearly are not designed with the aged in mind.

Research-Based Guidelines

Panayiotis Zaphiris, Mariya Ghiawadwala, and Shabana Mughal (2005) of the City University in London developed a set of age-centered Web design guidelines. These research-based guidelines were derived after an extensive literature review on aging and human interaction. They reviewed more than 100 research papers, and identified 52 unique guidelines. Each guideline was backed up with at least one established piece of literature. After a focus group and a card-sorting exercise with experienced usability specialists, the number of guidelines shrank from 52 to 38 guidelines.

Some of their most important guidelines for seniors included:

• Provide large targets, e.g., larger clickable graphics, for the mouse pointer.
• To reduce the number of clicks, do not require double clicking, use pull-down menus, nor have a deep hierarchy.
• Concentrate important information in the top central location of a home page or other Web page.
• Avoid the need to scroll down for information.
• Put most links in a bulleted list (not tightly clustered), and differentiate between visited and unvisited links.
• Use few colors, and avoid using blue and green tones.
• When text must be read or scanned, use 12-14 point sans serif (Helvetica, Arial) black text on a white background.
• The text should be left justified, and have increased spacing (leading) between lines.
• The main body of the text should be in sentence case, rather than all capital letters.
• The text should have appropriate, large headings in 14-16 sans serif font.

Six evaluators each reviewed two Web sites (nsclc.org and elderhostel.org) using the 38 guidelines. The guidelines enabled reviewers to achieve a 71% agreement. The authors concluded that the guidelines were robust and capable of being readily used and generalized.

Further Validation

Traci Hart, Barbara Chaparro, and Charles Halcomb (2004) at Wichita State University used 25 guidelines developed by the National Institute on Aging and the National Library of Medicine (2002). These “senior-friendly” guidelines were based on empirical research and were targeted for users 60 and over. The purpose of this study was to determine the degree to which perceived adherence to the guidelines had an impact on site performance and preference. They evaluated three sites with varying levels of guideline compliance:

• SeniorNet.com - High
• SeniorResource.com - Medium
• Seniors-Place.com - Low

They had 21 participants with an average age of 64, and an age range of 50 to 85, use the guidelines to rate the three sites. The top-rated site was SeniorNet, the moderately rated site was SeniorResource, and the lowest rated was Seniors-Place. They then conducted a usability test using a similar group of seniors who were in their own homes. Each participant performed five task scenarios at each site, and completed the System Usability Scale (SUS) for each of the sites.

The results showed that participants had reliably more success at SeniorNet than at Seniors-Place. On the System Usability Scale (SUS), participants rated the SeniorResource (SUS=80) site reliably better than the other two sites (both had SUS scores of 63). There was a significant correlation (r= .77) between sites rated as the “easiest” and the site “preferred most.” SeniorResource was rated the highest, and Seniors-Place the lowest.

They concluded that the Web site complying with the most senior-friendly guidelines had the highest task success, but did not result in significantly lower time on task, fewer number of pages visited, or the highest satisfaction or preference scores.

Conclusions

In both of these studies, the age-related research-based guidelines appeared to be very effective in helping to make the initial design decisions. Designers then should use usability testing to detect remaining usability issues. The research-based guidelines seemed to provide an excellent starting point, but they always should be combined with usability testing to help ensure a useful and usable system for older adults.

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Hart, T.A., Chaparro, B.S., Halcomb, H.C., (2004), Designing websites for older adults: The relationship between guideline compliance and usability software, Proceedings of the Human Factors and Ergonomics Society Annual Meeting.

Zaphiris, P., Ghiawadwala, M., and Mughal, S. (2005), Age-centered research-based web design guidelines, CHI 2005 Proceedings.