Effects of Physical Ability on Working Memory Requirements, Keystroke Rate, and Subjective Workload of Computer Input Devices

Abstract

A reasonable assumption might be that persons with limited physical ability (persons with cerebral palsy) will experience greater mental effort in performing a physical task. Three computer input devices were used to determine if differences in physical ability result in differences in mental workload estimated by working memory capacity, keystroke rate and efficiency, and subjective workload estimated by the Task Load Index (TLX). The three devices were a voice input system, trackball, and two-degree-of-freedom keyboard with headstick. Subjects with cerebral palsy used the three devices to perform a dual-task and their results were compared with those obtained from a sample of subjects without physical disabilities. Results showed no significant difference in normalized memory capacities between the two groups. However, there were significant differences in Normalized Working Memory Capacity between devices and trials for both groups. As expected, differences in physical ability produced significant differences in keystroke rate, keystroke efficiency, and subjective workload.