Contactless polygraph

Abstract

The constant transformation of our surroundings often goes unnoticed, but it occurs nonetheless. Imperceptibly, our skin undergoes slight color changes as our hearts beat, and our heads subtly move with each breath. While these alterations may escape our eyes, they are captured by cameras. We can magnify the variation in those small signals to extract important information such as heartbeat rate, which in turn can be used in many real-life applications such as polygraph tests. The polygraph, or lie detector test, is a tool that measures physiological changes in an individual to detect deception. This thesis aimed to explore the feasibility of using video information to extract heartbeat rates, replacing the traditional sensors that are commonly used to extract this information. Through a series of experiments involving videos of people standing still, and a video of a real-life suspect that was lying, it was consistently possible to enhance the color changes that occur in a person's skin when their heartbeats. Though it was not possible to develop a fully-functioning lie detector test, this thesis proves that the motion and color magnification technique is reliable even when applied to videos of individuals engaged in speech and movement. It also proved that it is an interesting solution that has the potential of revolutionizing how interviews and interrogations are conducted.