  This position paper describes an experiment conducted to understand the
relationships between different physiological measures including pupil
Diameter, Blinking Rate, Heart Rate, and Heart Rate Variability in order to
develop an estimation of users' mental load in real-time (see Sidebar 1). Our
experiment involved performing a task to spot a correct or an incorrect word or
sentence with different difficulties in order to induce mental load. We briefly
present the analysis of task performance and response time for the items of the
experiment task.
