Pupil Size Changes for Lie Detection in a Biofeedback Scenario

Recognizing a person’s intention has always been a part of psychological research. The current study investigates the potential of detecting false statements based on changes in pupil size. In two controlled laboratory experiments we differentiate pupil responses to intentional lies and to false statements made at the request of others. In addition, we use real-time feedback on pupil diameter to investigate the potential for voluntary suppression of dilation in the context of a false claim. The results show larger pupil diameters during free choices compared to instructed statements, especially when comparing the individual decision to lie to being asked to tell the truth. However, real-time feedback did not support voluntary control of pupil size changes.