Mental Workload Assessment Using Portable Test Bed: A Pilot Study

Monitoring and prediction of human performance in human-machine systems ensure safe and efficient system operation. An important factor affecting performance is the mental workload exhibited during the task. Higher mental workload results from elevated task demands requiring cognitive resources more than human capacity. The proposed study explores a portable test bed for assessing mental workload using multiple physiological measures and NASA-TLX subjective ratings. Using NASA Multi Attribute Task Battery (MATB-II), participants performed tracking and resource management tasks for three task loads with varying levels of difficulty. Physiological indices for electro cardiac activity, electroencephalogram, eye tracking, and skin conductance were recorded during the task using wearable technology except for eye tracker. The perceived workload was measured using the NASA-TLX scale after each task session. This paper explores the association of perceived workload and performance with different task loads. Significant degradation in tracking task performance was observed with an increase in the difficulty of task loads. The error increased by 45.6% for medium task load and 106% for high task load when compared to low task load. Resource management task performance was observed to be sensitive to task loads but no significant association was found. Subscales of NASA-TLX including temporal demand and effort could have the potential in distinguishing the task load levels. These findings indicate that the three task loads do induce different task demands.