Characteristics of alpha power event-related desynchronization in the discrimination of spontaneous deceptive responses.

Event-related desynchronization (ERD) occurs in the alpha frequency band when individuals are mentally active, and reflects increasing task demands. Lying involves a relatively greater cognitive load, and should be indicated by an increase of alpha power ERD. This study aimed to examine whether ERD discriminates deceptive responses from truthful responses. In the deception task, subjects made their own decision or were instructed either to type the presented numbers on the dice or input different numbers. Based on a subject's response and rule of the task, the type of response was determined. There were four types of responses: spontaneous deceptive, spontaneous truth, instructed deceptive, instructed truth. The findings of this study suggest that spontaneous deceptions produced significantly greater ERD than spontaneous truths, whereas ERD did not distinguish instructed deception from instructed truth. Different patterns between spontaneous and instructed deceptions may be due to different levels of cognitive load. Spontaneous lies require a greater cognitive load than other types of deceptions. The results of this study suggest that ERD has the potential to detect spontaneous deceptive responses. That is, ERD can detect deceptions that require cognitive effort in natural situations.