The influence of familiarity on life jacket donning performance: implications for participant selection.

Laboratories and test houses keep a "pool" of test subjects that volunteer to be participants in life jacket approval testing, which is believed to be an incorrect procedure. Fifty-six participants donned 8 child/infant life jackets onto 4 infant manikins in random order with time and accuracy of donning recorded. Average donning time for all 8 life jackets decreased significantly after the first donning experience. The findings show that the effect of familiarity occurs immediately after the first test, regardless of life jacket type, thus "contaminating" the subject and making them unsuitable for further tests. These observations are important for life jacket standards where the life jacket must be donned by a naïve participant. Currently, a poorly designed life jacket may receive a pass as a result of the learning effect as shown by participants with previous donning experiences.