[Evaluation of mental workload of short-term memory task by secondary task performance and frontal midline theta rhythm].

The purpose of the present study was to evaluate the mental workload of short-term memory task by two objective measures, the secondary task performance and the frontal midline theta rhythm (Fm theta) of the electroencephalogram (EEG). First, to choose Fm theta appearance subjects EEGs were recorded for 18 male students during performing additional task. On Fm theta appearance subjects (8 males) a series of short-term memory task with changed number of memorable figures was imposed as the primary task, and tracking task as the secondary task. The task that presents seven numbers will be over the subjects' limits of short-term memory, and it was the threshold that the subjects' mental workload will be increased.