Can human movement analysis contribute to usability understanding?

Nowadays human-machine interfaces are evaluated using different methodologies. These methodologies rarely consider the human movements involved in the interaction, and if so, the movements are considered in a simplistic manner. Another often neglected aspect is the relationship between the learning process and the use of the interface. Traditional approaches of cognitive modeling consider learning as just one continuous process. However there is some current evidence of concurrent processes on different time scales. This paper aims to answer, with experimental measurements, if learning actually implies a set of concurrent processes, if those processes are related to the coordinative aspects of hand movement, and how this can vary between young adult and elderly users. Two different interfaces, a washing machine and a domotic system, were analyzed with 23 and 20 people, respectively, classified as men or women and elderly (over 55) or adult (between 40 and 50). The results of the study provide support for the existence of different concurrent processes in learning, previously demonstrated for motor tasks. Moreover, the learning process is actually associated with changes in movement patterns. Finally, the results show that the progression of the learning process depends on age, although elderly people are equally capable of learning to use technological systems as young adults.