Three kinds of studies have been made in the attempt to discover the difference in attitude between truth and falsehood: association reactions, systolic blood pressure, and the ratio of inspiration time to expiration time in breathing. With an improved technique the author tested the value of the second and third of these indications, with especial attention to the third. Four series of experiments were carried out, in each of which the subject lied in a certain number of cases, and told the truth in others. Many of the tests gave inconclusive results, but some of them yielded evidence that seemed to be fairly reliable. More accurate diagnosis was obtained by using the evidence from blood pressure and breathing combined than from either separately. From Psych Bulletin 18:12:00696. (PsycINFO Database Record (c) 2006 APA, all rights reserved)