A Mixed Method for Evaluating Input Devices with Older Persons
Murni Mahmud · 2006 · Proceedings of the 8th International ACM SIGACCESS Conference on Computers and Accessibility (Assets '06) · doi:10.1145/1168987.1169063
Summary
This exploratory study introduces a mixed evaluation method for assessing common input devices used by older persons. The author argues that traditional input device studies rely too heavily on experimental tasks like Fitts's Law pointing tests, which use controlled stimuli that may not generalise to real-life situations. The proposed mixed method integrates four approaches: (1) psychometric tests to measure user ability, (2) subjective ratings of input devices collected before and after tasks, (3) real-world task performance with three input devices, and (4) post-task interviews to elicit user opinions about device qualities. Twelve older participants used a mouse, a tablet-with-stylus, and a touch screen to complete two tasks representing common computer activities: browsing a website (point and select) and playing a card game (point, drag, and drop). The study incorporated established psychometric instruments including the Mini-Mental State Examination (MMSE) for cognitive ability, the Identical Picture test (IP) for perceptual speed, and Simple Reaction Time (SRT) for motor performance. The research highlights that older people face particular disadvantages with common input devices due to reduced precision, slower movement, weakened shoulder muscles, and difficulty with eye-hand coordination.
Key findings
The mouse was the most efficient device for experimental (Fitts's Law) tasks, while in real tasks, the touch screen was most efficient for browsing and the mouse was most efficient for the card game. This divergence demonstrates that device performance is affected by the nature and complexity of tasks — a finding that would not have surfaced without using real tasks alongside experimental ones. Pre- and post-task subjective ratings showed users became more objective and realistic after actually performing tasks, with post-task ratings more closely matching observed performance. The SRT psychometric test proved a good indicator of users' performance across input devices, while the MMSE lacked sufficient variance among participants. Users' justifications for device preferences clustered around three theme types: Frequent themes (ease of use, difficulty, experience, screen, accessibility, fatigue), Recount themes (devices, users, tasks, methods, general technology, experiment), and Quality themes (effectiveness, efficiency, ease of use, satisfaction, accessibility, physical environment). The mouse received the most positive overall attitude, while the touch screen was seen as superior for accessibility but suffered from low effectiveness and satisfaction ratings.
Relevance
This paper offers a practical methodological contribution for anyone evaluating input devices or interaction techniques with older users. The mixed method approach — combining psychometric profiling, real tasks, subjective ratings, and qualitative interviews — produces richer insights than any single method alone. The finding that experimental tasks and real tasks yield different performance rankings is particularly important for accessibility practitioners: evaluations based solely on controlled pointing tasks may not reflect how older users actually interact with technology. The quality themes identified by users (effectiveness, accessibility, ease of use, physical environment) align with ISO 9241-11 usability definitions and provide a user-grounded framework for evaluating input devices. This work is directly applicable to designing accessible kiosks, touchscreen interfaces, and computing environments for ageing populations.
Tags: older adults · input devices · usability evaluation · mixed methods · psychometric testing · motor control · human factors
Standards referenced: ISO 9241-11