Examining the impact of familiarity on faucet usability for older adults with dementia

Abstract

Background: Changes in cognition caused by dementia can significantly alter how a person perceives familiarity, impacting the recognition and usability of everyday products. A person who is unable to use products cannot autonomously complete associated activities, resulting in increased dependence on a caregiver and potential move to assisted living facilities. The research presented in this paper hypothesised that products that are more familiar will result in better usability for older adults with dementia. Better product usability could, in turn, potentially support independence and autonomy.

Methods: This research investigated the impact of familiarity on the use of five faucet designs during 1309 handwashing trials by 27 older adults, who ranged from cognitively intact to the advanced (severe) stages of dementia. Human factors methods were used to collect empirical and self-reported data to gauge faucets' usability. Participants' data were grouped according to cognition (i.e., no/mild, moderate, or severe dementia). Logistic regression, ranking by odds, and Wald tests of odds ratios were used to compare performance of the three groups on the different faucets. Qualitative data were used in the interpretation of quantitative results.

Results: Results indicated that more familiar faucets correlated with lower levels of assistance from a caregiver, fewer operational errors, and greater levels of operator satisfaction. Aspects such as the ability to control water temperature and flow as well as pleasing aesthetics appeared to positively impact participants' acceptance of a faucet. The dual lever design achieved the best overall usability.

Conclusions: While work must be done to expand these findings to other products and tasks, this research provides evidence that familiarity plays a substantial role in product usability for older adults that appears to become more influential as dementia progresses. The methods used in this research could be adapted to analyse usability for other products by older adults with dementia.

Figure 1

The five faucet designs used in this study. Faucets were ordered from least usable (left) to most usable (right) based on a human factors approach and most familiar (left) to least familiar (right) based on average years of exposure and commercial availability. The plastic wand has not yet had a formal usability study, therefore could not be rated for usability. While familiarity plays a role in usability, the faucets were ordered independently for both usability and familiarity.

Figure 2

Proportion of the trials where: a) one or more errors were made by the participant when attempting to turn the water on and b) assistance was required by the participant to turn the water on.

Figure 3

Types of errors made for the (a) aware/mild, (b) moderate, and (c) severe levels of dementia groups. Note that more than one type of error could be made in the same trial, therefore the sum of the errors for a faucet type can be more than 100% (e.g., the moderate group’s use of the plastic wand; 38.9% + 40% + 48.9% + 2.2% = 130%).

Figure 4

Highest type of assistance required during each trial when turning the water on for the (a) aware/mild, (b) moderate, and (c) severe levels of dementia groups.

Figure 5

Average self-reported level of difficulty in response to the question “Do you think this faucet is easy or difficult to use?” Answers corresponded to a value on a four-point Likert scale where: 1 = very easy, 2 = easy, 3 = difficult, 4 = very difficult.