Performed by forced exhalation against a closed glottis, thus increasing internal abdominal and thoracic pressure. This results in a short-term increase in blood pressure and frequently a phasic electrodermal response. Because Valsalva’s maneuver can directly affect physiologic channels recorded with the polygraph, it is considered a type of physical countermeasures when used during testing. Named for eighteenth century Italian anatomist Antonio Maria Valsalva.