Remote Detection of Psychological Stress

Physiological stress can be characterized as dominance of the sympathetic branch of the autonomic nervous system over the parasympathetic branch. For example, when a person goes from a sitting position to the more physically stressful act of running, activity in the cardiac sympathetic nerves increases, and activity in the parasympathetic nerves decreases, leading to a faster heart rate and increased blood pressure among other things. Besides drastic changes in sympathetic/parasympathetic balance as in this example, there may be more subtle changes occurring on short timescales (seconds) in response to psychological stress (for example, not telling the truth while being questioned) or pathology (for example, internal hemorrhage of a patient in the intensive care unit).

Being able to track a person's physiological state noninvasively and on short time-scales would be beneficial from a basic science perspective as well as possibly improving the clinical outcomes of patients and in intelligence situations. Currently, there is no way of noninvasively measuring sympathetic or parasympathetic nervous tone, although several methods for estimating it exist, like for example, cardiovascular system identification (CSI). However, the present estimation methods require minutes of data, and are more effective at tracking general state rather than the potentially more important fluctuations on a beat-to-beat basis.

The goal of this project is to develop a noninvasive method for estimation of physiological stress. We aim to accomplish this using a few, easily measured signals, like the sequence of heart beat times and respiration. This data is routinely measured in intensive care wards, where the application of stress-monitoring may help predict unstable or decompensated states before they manifest with life-threatening symptoms. On the other hand, the data could be collected in a non-contact manner from subjects during a conversation, and stress-monitoring could alert the questioner about potentially sensitive topics or whether the subject is being deceitful in responses to particular queries.