A New Performance Measure Taking into Account the Mental Load in Mobile Text Entry Tasks

Text entry research has received a lot of attention in recent years because of the need for more effective and usable entry methods on mobile devices. Technical limitations such as screen size have led to the design of entry interfaces that mentally load the user in order to obtain better performances. Current evaluation methodologies of these interfaces focus on text entry speed and error rate but don’t pay enough attention to the mental load. In this paper, we concentrate on the evaluation of the load’s effect on text entry process and we present a comparative evaluation of three mobile text entry methods with and without the application of a secondary task. We also define a performance measure that takes into account the mental load characteristic for a given text entry interface.