The duration of inhalation compared with that of exhalation. Normally the ratio is about 1:2 in a resting human and changes during stress. It was first reported by Benussi in 1914. Changes in the I/E ratio are considered by some to be a diagnostic criterion in manual scoring. The I/E ratio as described by Benussi is quite different from that traditionally taught in polygraph schools. Also, more recent research has not found it to be of diagnostic value in manual scoring. See: Krapohl, (2020); Kircher, Kristjansson, Gardner, & Webb (2005).
