Evaluation of Input - Side Parameter of Productivity by Cerebral Blood Oxygenation Changes

To evaluate effect of indoor environment quality on productivity, the changes in cerebral bloodoxygenation by near infrared spectroscopy was examined. In this study, relationship between the changes in cerebral blood oxygenation and difficulty level of task was evaluated by subjective experiments. Four tasks were given to the subjects: single-digit addition, double-digit multiplication, triple-digit addition, and triple-digit multiplication. It was evaluated that the more difficult task types to solve, the more oxygenated hemoglobin and total hemoglobin concentration were needed. There was a significant correlation between subjective value of mental demand for tasks and the left side of total hemoglobin concentration. It was shown that tasks that needed higher mental demand required more cerebral blood flow. Monitoring cerebral blood oxygenation changes might be applied to the evaluation of input-side parameter of productivity that shows the degree of mental effort to do the task.