People over the age of 65 represent the fastest growing demographic worldwide. By 2020, it is expected that over one billion senior citizens will be alive on the planet. (Zaphiris, Ghiawadwala, and Mughal, 2005).
Known Limitations due to the Aging Process
Of concern to user interface designers are known limitations due to the aging process. These limitations include:
- Reduced visual ability
- Hearing loss
- Psychomotor impairments
- Loss of fine motor control
- Attentional factors
- Learning and memory impairments
These limitations must be taken into consideration when designing systems used by aging populations. This effort has other benefits. Research has demonstrated that improving the usability of systems for elderly, limited cognition, or visually impaired populations allow the public, as a whole, to benefit from improved usability (Chadwick-Dias, McNulty, and Tullis, 2003).
Effect of Font Size
Chadwick-Dias, McNulty, and Tullis (2003) studied the impact of font size on the completion of routine tasks on an employee/retiree Web site. Participants’ age ranged from 20 to 82 and experience level was balanced across age groups. The researchers presented the site in three different font sizes. Older users (55+) had more difficulty in accomplishing the routine tasks then younger users but font size did not influence performance. Older adults were more likely to select non-linked text such as bullets, icons, and table headings and averaged significantly fewer clicks per minute than younger adults.
Intrigued by their findings, Chadwick-Dias et al (2003) conducted a second study with the same age groups (different participants) but this time they redesigned the site to adhere to a set of usability guidelines. Both the elderly and younger groups showed marked improvement in success rate and decreased time on task. Unlike the first experiment there was no significant difference for number of clicks by group. Like the first experiment there was no font size effect.
In both studies, older users took longer to complete tasks and completed fewer task then their younger counterparts. There was a strong relationship between performance and experience, demonstrating the balancing of the experience factor across groups. This finding shows that there are factors independent of experience that account for degradation of the seniors’ performance.
Effect of Navigation and Usability
Nayak et al (2006) examined the effect of font size and design attributes on comprehension. One hundred and five seniors ranging from 58 to 90 years of age participated in the study. Findings showed that 33% of the participants found 8-9 point font size too small with an additional 22% finding 10-point text too small.
More interesting then font size, results from their research demonstrated that the most important factor for increasing usability for the elderly is the use of consistent and persistent navigation.
Other findings supported:
- The use of large, easy to read text with high contrast
- Facilitation of visual search efficiency and selective attention by limiting the amount of information on each page
Hart and Chapparro (2004) studied the effect of well-designed sites on the older population’s performance. They evaluated 36 Web sites with older adult specific content by using a set of senior-friendly guidelines compiled by the National Institute of Aging. Main guideline categories of the checklist included: designing readable text, increasing memory and comprehension, and increasing ease of navigation.
They chose the Web sites used in the study by searching for keywords like seniors, elderly, or older adults. Results showed that 22% of the sites were rated as low compliance, 47% were rated as medium compliance, and only 30% were rated as high in compliance.
Effect of Domain Name Extensions
Zaphiris and Kurniawan (2001) were interested in the relationship between type of domain name extensions (i.e., .com, .edu, .gov and .org) and various levels of usability and disability friendliness/accessibility for aging and health-related Web sites. The researchers used two automatic evaluation tools, LIFT (overall usability) and Bobby (overall accessibility) to evaluate the sites. They analyzed between twenty – 25 sites representing each extension.
Results showed that governmental sites (.gov) performed best in both accessibility and overall usability no doubt due to tougher government accessibility requirements. Commercial sites performed very well in terms of usability but poorly in accessibility. Consistent with other research (Hart & Chaparro, 2004) more accessible and compliant sites are more usable.
The elderly are an important population to consider when designing Web sites. Their demographic is growing at an increased rate as well as their technology expertise. Research shows that independent of expertise, the elderly face unique usability concerns that need to be addressed. These limitations are likely due to a combination of social, cognitive, psychological, and physical factors. On a promising note, the elderly population shows the same increase in performance as their younger counterparts when Web sites are designed to conform to general usability principles and guidelines.
Ann Chadwick-Dias, Michelle McNulty, Tom Tullis, Web usability and age: how design changes can improve performance, Proceedings of the 2003 conference on Universal usability, November 10-11, 2003, Vancouver, British Columbia, Canada.
Nayak L, Priest L, Stuart-Hamilton I, et al. Web site design attributes for retrieving health information by older adults: an application of architectural criteria. Universal Access in the Information Society 2006;5: 170–9.
Zaphiris, P., Kurniawan, S.: Usability and Accessibility of Aging/Health-Related
Web sites. HCI International, New Orleands, LA, USA, 2001.
Zaphiris, P., Ghiawadwala, M., and Mughal, S. 2005. Age-centered research-based web design guidelines. In CHI ’05 Extended Abstracts on Human Factors in Computing Systems (Portland, OR, USA, April 02 – 07, 2005). CHI ’05. ACM, New York, NY, 1897-1900.