Usability evaluation of numeric entry tasks on keypad type and age

Abstract

This study investigated the effects of age and two keypad types (physical keypad and touch-screen one) on the usability of numeric entry tasks. Twenty four subjects (12 young adults 23–33 years old and 12 older adults 65–76 years old) performed three types of entry tasks: 4-digit, 4-digit of password type, and 11-digit. The dependent variables for the performance were mean entry time per unit stroke and error rate. Subjective ratings for ease of use of each keypad type were collected after the experiment. The mean entry time per unit stroke of the young adults was significantly smaller than that of the older adults. The older adults had significantly different mean entry times per unit stroke on the two keypad types. The error rates between young and older adults were significantly different for the touch-screen keypad. The subjective ratings showed that the participants preferred the touch-screen keypad to the physical keypad. The results showed that the older adults preferred the touch-screen keypad and could operate more quickly, and that tactile feedback is needed for the touch-screen keypad to increase input accuracy. The results of this study can be applied when designing different information technology products to input numbers using one hand. Relevance to industry Touch-screen technology is increasingly used in ticketing Kiosks used in public places such as airports, stations or theaters, and in automated teller machines (ATMs) and cash dispensers (CDs). This paper can be applied to design these products or systems, particularly considering usability improvements for older adults.