Guidelines for force-travel combinations of push button switches for older populations

Current demographic trends indicating that older persons will comprise an increasingly larger proportion of our population points to the need for paying closer attention to age-related disabilities in designing products and environments capable of accommodating this population. This study addresses the development of design guidelines for push-button switches associated with a variety of consumer products commonly used by older persons. Three groups, each consisting of 12 male and female subjects, participated in the study, with all subjects over the age of 50 and the average age being 70 years. The groups were categorized on the basis of whether subjects were able-bodied, had arthritis affecting their hands or fingers, or had hand tremor; these categories were validated through the use of functional assessment tools. A scheme was developed to categorize commercially available switches based on force-travel combinations, and an experiment was conducted to assess the subject's ability to momentarily and continuously operate the switches, as well as to derive the subjective preferences for these switches. Based on observations from behavioral strategies, and graphical and statistical analysis of preferences, a set of design guidelines was proposed to enable consumer product designers and manufacturers to better accommodate the needs of both able-bodied and functionally impaired older adults.