The performance and physical responses during an attention shift task with grapefruit and skatole odor presentation

Performance and physiological responses within performing an attention shift task were compared between grapefruit odor, skatole, odorless air presentation. Ten male students participated in this experiment. They performed 15 min digit detection task three times, that required quick attention shift. During the task, 1 min odor was presented three times. Near infrared spectroscopy and EEG were monitored through the experiment, and offered physiological indexes of oxy-Hb, deoxy-Hb and beta wave component. The number of correct responses and reaction time were better in both grapefruit and skatole presentation than in odorless air. Increased oxy-Hb that indicates activated brain function, was observed only in grapefruit presentation at left forehead. Increased beta wave component that reflects relaxation, was found in grapefruit presentation at F4 (left middle forehead), while decreased beta in skatoke presentation. These findings suggest grapefruit acts as an activator, while skatole as a sedative.